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Development of a salt marsh on the Fraser delta at Boundary Bay, British Columbia, Canada Shepperd, Jane Elizabeth 1981

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DEVELOPMENT OF A SALT MARSH ON THE FRASER DELTA AT BOUNDARY BAY, BRITISH COLUMBIA, CANADA by JANE ELIZABETH SHEPPERD B . S c , U n i v e r s i t y o f N e w c a s t l e upon Tyne, 1979 • A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n ° THE FACULTY OF GRADUATE STUDIES (Department o f G e o l o g i c a l S c i e n c e s ) We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1981 © Jane E l i z a b e t h Shepperd, 1981 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study. I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the head o f my department o r by h i s o r her r e p r e s e n t a t i v e s . I t i s understood t h a t copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be allowed without my w r i t t e n p e r m i s s i o n . Department o f OKOIC^J  The U n i v e r s i t y o f B r i t i s h Columbia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 D a t e M r u | | I 9 3 DF-fi c?/7<n i i S a l t marshes are "areas of land bordering on the sea, more or l e s s covered with v e g e t a t i o n and s u b j e c t to p e r i o d i c inundation by the t i d e . They o r i g i n a t e as bare mud- or s a n d - f l a t s which, as they become higher, are c o l o n i z e d by algae and f l o w e r i n g p l a n t s , the s p e c i e s i n v o l v e d v a r y i n g i n d i f f e r e n t p a r t s of the world. The p l a n t s are enabled to occupy t h i s h a b i t a t by v i r t u e of t h e i r t o l e r a n c e of the s p e c i a l c o n d i t i o n s o b t a i n i n g i n marshes. The advent of the p l a n t s on the bare f l a t s promotes f u r t h e r growth in height of the land which, as t h i s ' r i s i n g ' takes p l a c e , r e s u l t s in changes i n the environment so that d i f f e r e n t s p e c i e s can enter the area. S a l t marshes, t h e r e f o r e , may extend v e r t i c a l l y from about mean sea l e v e l up to the extreme upper l i m i t of the t i d e s , where they w i l l abut on normal land vege-t a t i o n or e l s e grade i n t o freshwater swamp." (Chapman, 1960, p. 1) i i i ABSTRACT The development of a l a t e Holocene s a l t marsh was s t u d i e d on the i n a c t i v e p a r t of the F r a s e r D e l t a a t Boundary Bay, s o u t h -w e s t e r n B r i t i s h Columbia. P r e s e n t - d a y v e g e t a t i o n zones near 64th S t r e e t , South D e l t a , i n the western p a r t of the Bay, were d i s t i n g u i s h e d i n the s a l t marsh and were r e l a t e d t o zones found i n c o r e s o b t a i n e d i n a t r a n s e c t a c r o s s the marsh. A sequence of development, r e l a t e d t o e l e v a t i o n , was d e t e r m i n e d . S a l i c o r n i a and T r i g l o c h i n a re p i o n e e r c o l o n i z e r s of the t i d a l f l a t s and are sometimes a s s o c i a t e d w i t h a r e a s e l e v a t e d by a l g a l mats. As the are a was e l e v a t e d , sediments were t r a p p e d by v e g e t a t i o n and s t a -b i l i z e d by rhizo m e s , and o t h e r h a l o p h y t e s grew, i n c l u d i n g C u s c u t a , S p e r q u l a r i a , A t r i p l e x , D i s t i c h l i s , G r i n d e l i a , and P l a n t a g o . A zone c h a r a c t e r i z e d by abundant A t r i p l e x r e p r e s e n t s p o s i t i o n s of former s t r a n d l i n e s . As f u r t h e r emergence o c c u r r e d , mesophytes became dominant and, i n the landward, most emergent zone, a d i v e r s e f l o r a of Maius, S j d a l c e a , A s t e r , A c h i I l e a , S o l i d a q o , Elymus, A n g e l i c a , J u n c u s , and g r a s s e s d e v e l o p e d . A r a d i o c a r b o n date on S a l i c o r n i a - r i c h o r g a n i c s i l t s a t a depth of 35 t o 40 cm i n c o r e 5 suggests t h a t s a l t marsh development com-menced 320 ± 70 y e a r s B.P. (GSC-3186). A former s a l t marsh peat i s now p a r t i a l l y b u r i e d and b e i n g a c t i v e l y eroded where exposed near 112th S t r e e t , South D e l t a , i n e a s t e r n Boundary Bay. A p a l e o e n v i r o n m e n t a l r e c o n s t r u c t i o n sug-g e s t s the peat s t a r t e d d e v e l o p i n g i n f r e s h w a t e r , w i t h f e r n s , sedges, Typha, and Nuphar. L a t e r , i t was s u c c e s s i v e l y i n u n d a t e d by marine water and a s a l t marsh d e v e l o p e d , as seen by an i n -i v crease in the abundance of chenopod p o l l e n . Subsequent emer-gence of the s a l t marsh was accompanied by the development of an i n c r e a s i n g l y d i v e r s e v e g e t a t i o n . V TABLE OF CONTENTS. Page ABSTRACT i i i TABLE OF CONTENTS . V LIST OF TABLES v i i LIST OF FIGURES ' v i n ACKNOWLEDGEMENTS x l CHAPTER 1: INTRODUCTION 1 Regional Setting 4 Geological History 6 The Study Area 8 CHAPTER 2: METHODS 15 F i e l d Methods 15 Laboratory Methods 2 0 Po l l e n and Spore I d e n t i f i c a t i o n 27 CHAPTER 3: RESULTS 31 The S a l t Marsh at 64th Street 31 D i s t r i b u t i o n of Vegetation 31 D i s t r i b u t i o n of Modern Pollen 3 9 Formation of the Salt Marsh 43 Development of the Salt Marsh 47 Rates of Development and Accretion of the Sa l t 54 Marsh The Peat at 112th Street 56 CHAPTER 4: DISCUSSION AND CONCLUSIONS 60 REFERENCES CITED 6 3 APPENDIX I: Pollen Diagrams and Descriptions of 68 the Cores v i TABLE OF CONTENTS (cont'd) APPENDIX I I : P o l l e n Assemblage Data f o r the S t a t i o n s on the S a l t Marsh at 64th S t r e e t v i i LIST OF TABLES. T a b l e Page 1. Summary of the g e o l o g i c a l h i s t o r y o f the F r a s e r 7 Lowlands. 2. V e g e t a t i o n found at 6 4th S t r e e t . 19 v i i i LIST OF FIGURES. F i g u r e p a g e 1. Map o f t h e F r a s e r D e l t a a r e a , showing t h e l o c a t i o n 2 o f Boundary Bay. 2. Map o f Boundary Bay showing l o c a t i o n s o f t h e s t u d y 9 ar e a s ( m o d i f i e d a f t e r Swinbanks, 1979). 3. Summary o f t h e s u b d i v i s i o n s o f t h e Boundary Bay 13 t i d a l f l a t s , a c c o r d i n g t o Swinbanks and K e l l e r h a l s and Murray. 4. The s a l t marsh a t 6 4 t h S t r e e t , showing s t a t i o n 16 l o c a t i o n s and t h e v e g e t a t i o n zones. 5. Map showing l o c a t i o n o f c o r e s o b t a i n e d n e a r 1 1 2 t h 16 S t r e e t . 6. A g o s e r i s sp. S.E.M. P h o t o g r a p h . ( S c a l e b a r 23 r e p r e s e n t s 2um). 7. G r i n d e l i a i n t e g r i f o l i a . S.E.M. P h o t o g r a p h . 25 8. A s t e r s u b s p i c a t u s . S.E.M. P h o t o g r a p h . 25 9. S e l e c t e d p o l l e n g r a i n s from t h e s a l t marsh 28 v e g e t a t i o n . a. S a l i c o r n i a v i r g i n i c a (x 1000). b. A t r i p l e x p a t u l a (x 100 0 ) . c. C u s c u t a s a l i n a (x 1000) . d. S p e r g u l a r i a m a r i n a (x 1000) . e. A s t e r s u b s p i c a t u s (x 1000) . f . S o l i d a g o sp. (x 1000). g. A c h i l l e a m i l l e f o l i u m (x 1000) . h. G r i n d e l i a i n t e g r i f o l i a (x 1000). i . Elymus m o l l i s (x 1000). j . D i s t i c h l i s s p i c a t a (x 1000). k. P l a n t a g o m a r i t i m a (x 1000) . 1. S i d a l c e a h e n d e r s o n i (x 500) . m. T r i g l o c h i n maritimum (x 1000). n. A n g e l i c a l u c i d a (x 1000). o. Juncus b a l t i c u s (x 1000) . p. A g o s e r i s sp. (x 1000) . 10. The most landward p a r t o f t h e s a l t marsh n e a r t h e dyke 32 ( s c a l e i s 30 cm). 11. The c h a n n e l by S t a t i o n 2 a , i n w h i c h D i s t i c h l i s s p i c a t a , 32 G r i n d e l i a i n t e g r i f o l i a and S a l i c o r n i a v i r g i n i c a grow. 12. E e l g r a s s , washed i n by s t o r m s , around T r i g l o c h i n  maritimum ( s c a l e i s 3Q cm). 35 i x LIST OF FIGURES ( c o n t ' d ) . F i g u r e Page 1^* A t r i p l e x p a t u l a g r o w i n g a l o n g t h e s t r a n d l i n e . 37 The submergent marsh can be seen seaward o f t h i s zone. 14. H a l o p h y t e hummocks beyond t h e seaward edge o f 3 7 th e c o n t i n u o u s marsh. 15. A l g a l mats s t a b i l i z i n g r i p p l e s on t h e h i g h 40 t i d a l f l a t s ( s c a l e i s 30 cm). 16. A l g a l mats b i n d i n g washed-in e e l g r a s s b l a d e s . 40 17. P o l l e n assemblages c o l l e c t e d a t t h e S t a t i o n s 42 o v e r t h e t r a n s e c t on t h e s a l t marsh a t 64th S t r e e t from May t o November, 1981. 18. P i o n e e r S a l i c o r n i a v i r g i n i c a on t h e h i g h t i d a l 44 f l a t s ( s c a l e i s 30 cm). 19. S m a l l T r i g l o c h i n maritimum hummock ( s c a l e i s 44 30 cm). 20. Summary o f t h e development o f t h e s a l t marsh a t 49 64 t h S t r e e t . 21. A l g a l l a m i n a t i o n s seen n e a r S t a t i o n 8. 51 22. Composite s e c t i o n o f zones found i n t h e c o r e s 57 o b t a i n e d n e a r 1 12th S t r e e t . 23. P o l l e n d i a g r a m o f the Dyke Core. 70 24. P o l l e n d i a g r a m o f Core 1. 72 25. P o l l e n d i a g r a m o f Core 2. 73 26. P o l l e n d i a g r a m o f Core 3. 75 27. P o l l e n d i a g r a m o f Core 4. 76 28. P o l l e n d i a g r a m o f Core 5. 78 29. P o l l e n d i a g r a m o f Core 6. 80 30. P o l l e n d i a g r a m o f Core 7. 80 31. P o l l e n d i a g r a m o f Core 8. 82 32. P o l l e n d i a g r a m o f Core 9. 82 33. P o l l e n d i a g r a m o f Core 10. 82 X LIST OF FIGURES ( c o n t ' d ) . F i g u r e Page 34. P o l l e n d i a g r a m o f Core 11. - 84 35. P o l l e n d i a g r a m o f Core 12. 86 36. P o l l e n d i a g r a m o f Core 13. 86 x i ACKNOWLEDGMENTS S i n c e r e thanks a re extended t o Dr. W.C. Barnes, my s u p e r v i -s o r , f o r c o n t i n u e d a s s i s t a n c e , encouragement, and a d v i c e d u r i n g t h i s s t u d y , f o r h e l p w i t h photography, and a l l h i s a s s i s t a n c e d u r i n g the c o m p l e t i o n of the m a n u s c r i p t . I am a l s o v e r y g r a t e -f u l t o Dr. G.E. Rouse f o r h i s g r e a t e n t h u s i a s m , s u g g e s t i o n s , and a s s i s t a n c e , e s p e c i a l l y w i t h the p a l y n o l o g y , d u r i n g the study and the w r i t i n g of the r e p o r t . A p p r e c i a t i o n i s a l s o e x p r e s s e d t o Dr. R.M. B u s t i n f o r c r i -t i c a l l y r e a d i n g and r e r e a d i n g the m a n u s c r i p t , Gord Hodge f o r the d r a u g h t i n g , and Roberta Crosby f o r her time and p a t i e n c e w h i l s t t y p i n g the m a n u s c r i p t . Thanks are extended t o Drs. J . Clague and J . L u t e r n a u e r , of the G e o l o g i c a l Survey of Canada, f o r f r u i t f u l d i s c u s s i o n and a s s i s t a n c e . The r a d i o c a r b o n d a t e s were d e t e r m i n e d by Dr. W. B l a k e , G e o l o g i c a l Survey of Canada, and Teledyne I s o t o p e s . The study upon which t h i s t h e s i s i s based was su p p o r t e d by a Department of Energy, Mines and Resources Research Agreement, by N a t u r a l S c i e n c e s and E n g i n e r i n g R e s e a r c h C o u n c i l Grant A-2027, and by a U n i v e r s i t y of B r i t i s h Columbia N a t u r a l and H e a l t h S c i e n c e s G r a n t , a l l t o Dr. W.C. Barnes. F i n a l l y , I thank f e l l o w graduate s t u d e n t s B i l l Styan f o r plane t a b l i n g the study a r e a s , f o r numerous d i s c u s s i o n s , and f o r s h a r i n g common problems, and E i l e e n W i l l i a m s f o r her w i l l i n g a s s i s t a n c e and h e l p f u l s u g g e s t i o n s . K e v i n T r a v i s h e l p e d me i n x i i t h e f i e l d . I t h a n k M a r t i n H o u s t o n f o r h e l p i n t h e f i e l d a n d w i t h p h o t o g r a p h y , and f o r h i s e n c o u r a g e m e n t . 1. CHAPTER 1: INTRODUCTION . The s u b a q u e o u s p a r t o f t h e l o w e r d e l t a p l a i n o f t h e F r a s e r D e l t a i s a b r o a d , g e n t l y s l o p i n g t i d a l f l a t w h i c h i s 6 km w i d e on t h e a c t i v e w e s t e r n p o r t i o n o f t h e d e l t a a n d 4 km w i d e on t h e i n a c t i v e , s o u t h - f a c i n g p o r t i o n . S a l t m a r s h e s a r e l o c a l l y d e v e l -o p e d on t h e u p p e r m o s t e m e r g e n t p a r t s o f t h e t i d a l f l a t s . T h e d i s t r i b u t i o n o f s a l t m a r s h h a s b e e n mapped by B e c k e r ( 1 9 7 1 ) , F o r b e s ( 1 9 7 2 ) , a n d Yamanaka ( 1 9 7 5 ) . Moody ( 1 9 7 8 ) s t u d i e d t h e m a r s h e s a t B r u n s w i c k P o i n t , a n d a summary r e p o r t o f t h e m a r s h c o m m u n i t i e s was p r e p a r e d by E n v i r o c o n ( 1 9 8 0 ) . T h e p r e s e n t s t u d y i s c o n c e r n e d w i t h t h e d e v e l o p m e n t o f t h e s a l t m a r s h on a s m a l l a r e a o f t h e t i d a l f l a t s i n B o u n d a r y Bay, on t h e i n a c t i v e s o u t h e r n - f a c i n g d e l t a f r o n t ( F i g u r e 1 ) . The m a r s h i s t h e l e a s t i n f l u e n c e d by t h e F r a s e r R i v e r o f a l l t h e m a r s h e s d e v e l o p e d on t h e t i d a l f l a t s ( P a r s o n s , 1975; Y a m a naka, 1 9 7 5 ) . The s t u d y a r e a i s l o c a t e d 19 km s o u t h o f V a n c o u v e r , B r i t i s h C o l u m b i a , a t L a t . 4 9 ° 0 4 ' N a n d L o n g . 1 2 3 ° 0 0 ' W ( F i g u r e 1 ) . I t i s s e p a r a t e d f r o m t h e a c t i v e w e s t e r n d e l t a f r o n t a n d p r o t e c t e d f r o m t h e S t r a i t o f G e o r g i a by P o i n t R o b e r t s , t h u s h a v i n g r e l a -t i v e l y s m a l l wave h e i g h t s . S a l t m a r s h d e v e l o p m e n t i n B o u n d a r y Bay i s n o t u n i f o r m ; a t 6 4 t h S t r e e t , S o u t h D e l t a , an e x t e n s i v e m a r s h was c h o s e n f o r s t u d y ( F i g u r e 2 ) . T h i s m a r s h i s b r o a d e r a n d h a s b e t t e r d e v e l o p e d p l a n t z o n a t i o n t h a n on o t h e r p a r t s o f t h e F r a s e r D e l t a . The s e d i m e n t a r y p r o c e s s e s o f t h e t i d a l f l a t s s e a w a r d o f t h e m a r s h e s were s t u d i e d by S w i n b a n k s ( 1 9 7 9 ) , a n d K e l l e r h a l s a n d M u r r a y ( 1 9 6 9 ) d e s c r i b e d t h e t i d a l f l a t s . T h e s a l t m a r s h i s t h e l a s t m a j o r z o n e whose s e d i m e n t a r y h i s t o r y h a s 2. H 4 9 Ple i s tocene glacial and fluvioglacial depos i ts 0 4 = 10 kilometres 123' 'igure'1. Map o f the F r a s e r D e l t a a r e a , showing the l o c a t i o n o f Boundary Bay. 3. r e m a i n e d u n s t u d i e d . The a i m o f t h i s i n v e s t i g a t i o n was t o i n t e r p r e t t h e d e v e l o p -ment o f t h e s a l t m a r s h , u s i n g b i o s t r a t i g r a p h y , s e d i m e n t o l o g y , a n d g e o c h r o n o l o g y . C o r e s w e r e c o l l e c t e d a n d p r o c e s s e d f o r p a -l y n o m o r p h s , a n d p o l l e n t r a p s w e r e m o n i t o r e d t h r o u g h o u t t h e grow-i n g s e a s o n o v e r t h e s t u d y a r e a , w i t h t h e o b j e c t i v e o f r e l a t i n g h o r i z o n t a l f a c i e s on t h e p r e s e n t - d a y f o r e s h o r e t o v e r t i c a l z o n e s i n t h e c o r e s . 4. R e g i o n a l S e t t i n g The F r a s e r D e l t a extends 31 km west from New Westminster t o the S t r a i t of G e o r g i a and south i n t o Boundary Bay ( F i g u r e 1 ) . The topography of the d e l t a a rea i s low, b e i n g o n l y a few metres above mean sea l e v e l ( K e l l e r h a l s and Murray, 1969); i t i s bounded on the n o r t h by the B u r r a r d P e n i n s u l a and on the e a s t by the S u r r e y Uplands, w h i l s t the i n a c t i v e s o u t h e r n p a r t , Boundary Bay, i s bounded on the southwest by P o i n t R o b e r t s , a former i s l a n d of P l e i s t o c e n e g l a c i a l and g l a c i o f l u v i a l sediments j o i n e d t o the mainland by the development of the d e l t a ( J o h n s t o n , 1921a). The d e l t a meets the sea a l o n g a p e r i m e t e r of more than 50 km, of which 37 km form the a c t i v e western d e l t a - f r o n t f a c i n g the S t r a i t of G e o r g i a between the B u r r a r d P e n i n s u l a and P o i n t R o b e r t s . The abandoned p a r t of the d e l t a extends 13 km e a s t from P o i n t R o b e r t s , f a c i n g s o u t h i n t o Boundary Bay. The F r a s e r D e l t a p r e s e n t s the form of a h i g h grade d e l t a ( J o h n s t o n , 1921a) b u i l d i n g out i n t o the deep water of the S t r a i t of G e o r g i a , a l a r g e , s e m i - e n c l o s e d , marine waterway, s e p a r a t i n g Vancouver I s l a n d , on the southwest, from the mainland of B r i t i s h Columbia ( F i g u r e 1 ) . The seaward f r o n t of the d e l t a , b e i n g swept by s t r o n g n o r t h e r l y - t r e n d i n g f l o o d t i d a l c u r r e n t s , has a smooth l o b a t e o u t l i n e , which J o h n s t o n (1921a) c a l l e d a r c u a t e . Four main d i s t r i b u t a r y c h a n n e l s c r o s s the F r a s e r D e l t a ; the two major ones a r e known as the N o r t h Arm and the Main Channel. The s e d i m e n t a t i o n of the western d e l t a - f r o n t has been d e s c r i b e d by L u t e r n a u e r and Murray (1973). The F r a s e r R i v e r i s 1370 km l o n g , r i s i n g on t h e w e s t e r n s l o p e o f t h e R o c k y M o u n t a i n s a t 5 3 ° N , w i t h a d r a i n a g e b a s i n o f 234,000 km 2. T h e r i v e r i s t i d a l up t o C h i l l i w a c k , 105 km u p s -t r e a m , a t low f l o w s (November t o M a r c h ) , b u t o n l y up t o M i s s i o n , 80 km u p s t r e a m , d u r i n g t h e r e m a i n d e r o f t h e y e a r ( H o o s a n d Packman, 1 9 7 4 ) . The mean t i d a l r a n g e a t t h e r i v e r m o u t h i s 1.95 m, w i t h a maximum o f 4.6 m ( J o h n s t o n , 1 9 2 2 ) . The h i g h e s t w a t e r o c c u r s d u r i n g t h e May t o J u l y f r e s h e t . A t low f l o w s , a wedge o f d e n s e r s a l i n e w a t e r e x t e n d s u p s t r e a m f o r 21 km b e n e a t h t h e l e s s d e n s e r i v e r w a t e r ; t h e u p s t r e a m e x t e n t o f t h i s wedge i s r e d u c e d d u r i n g t h e summer ( G a r r i s o n e_t a _ l . , 1 9 6 9 ) . The r i v e r c o n t r i b u t e s 2.0 x 1 0 7 m 3 o f v e r y f i n e s a n d a n d s i l t t o t h e S t r a i t o f G e o r g i a e a c h y e a r (Mathews a n d S h e p a r d , 1962; P h a r o a n d B a r n e s , 1 9 7 6 ; M i l l i m a n , 1 9 8 0 ) . Much o f t h e s e d -i m e n t o f B o u n d a r y Bay, h o w e v e r , i s d e r i v e d f r o m wave e r o s i o n o f t h e P o i n t R o b e r t s P e n i n s u l a . The s e a w a r d a d v a n c e o f t h e d e l t a was e s t i m a t e d by J o h n s t o n ( 1 9 2 1 b ) t o be 3 m p e r y e a r ; i t s t o t a l v o l u m e i s 8.92 x 10 m 3; i t s t h i c k n e s s i s 214 m, a n d i t s s u b s i d e n c e r a t e i s 0.012 m p e r d e c a d e (Mathews e t a l . , 1 9 7 0 ) . 6. G e o l o g i c a l H i s t o r y The g e o l o g i c a l h i s t o r y o f t h e F r a s e r L o w l a n d s a r e a i s b r i e f l y s u m m a r i z e d i n T a b l e 1. J o h n s t o n ( 1 9 2 3 ) , L u t e r n a u e r ( 1 9 7 4 ) , a n d B l u n d e n ( 1 9 7 5 ) r e v i e w e d t h e g e o l o g y o f t h e L o w e r F r a s e r V a l l e y , J o h n s t o n ( 1 9 2 1 a , 1 9 2 1 c ) , A r m s t r o n g ( 1 9 5 6 a , 1956b, 1957, 1 9 6 0 ) , A r m s t r o n g a n d C l a g u e ( 1 9 7 7 ) , C l a g u e ( 1 9 7 6 , 1 9 7 8 ) , a n d C l a g u e e_t a _ l . ( 1 9 8 0 ) h a v e i n t e r p r e t e d t h e P l e i s t o c e n e h i s -t o r y a n d s u r f i c i a l d e p o s i t s , a n d M a t h e w s e t a l . ( 1 9 7 0 ) h a v e d e -s c r i b e d p o s t - g l a c i a l c r u s t a l m o v e m e n t s o f t h e a r e a . A b o u t 8,000 y e a r s ago ( J o h n s t o n , 1 9 2 1 a ; M a t h e w s , 1972; B l u n d e n , 1 9 7 3 ) , t h e F r a s e r R i v e r b e g a n t o f a n o u t a t New W e s t m i n s t e r a n d f o r m t h e m o d e r n d e l t a . A t New W e s t m i n s t e r , t h e r i v e r h a s b e e n c o n t a i n e d i n a v a l l e y 60 t o 90 m w i d e t h r o u g h o u t t h e f o r m a t i o n o f t h e m odern d e l t a ( J o h n s t o n , 1 9 2 1 b ) . As a c o n s e q u e n c e o f t h e Sumas e m e r g e n c e ( T a b l e 1 ) , p e a t b o g s t h a t a r e now 11 m b e l o w s e a l e v e l d e v e l o p e d on r a i s e d F r a s e r R i v e r a l l u v i u m ( Mathews e t a _ l . , 1 9 7 0 ) . T h e s e p e a t s i n -c l u d e t h o s e a d j a c e n t t o t h e P o r t Mann B r i d g e ( F i g u r e 1 ) , d a t e d a s 7,500 y r s B.P. ( 5 - 9 9 , G S C - 2 ) , a n d t h e p e a t i n P i t t Meadows A i r p o r t , b e i n g 8,290 y r s B.P. ( G S C - 2 2 9 ) . Sea l e v e l h a s r e m a i n e d n e a r i t s p r e s e n t l e v e l f o r t h e p a s t 5,500 y e a r s , w i t h some m i n o r f l u c t u a t i o n s . A p e a t a t 1 1 2 t h S t r e e t , B o u n d a r y Bay ( F i g u r e 2 ) , d a t e d a s 4,350 y r s B.P. (GX-0 7 8 1 ) , o c c u r s 1.8 m b e l o w t h e e l e v a t i o n a t w h i c h s u c h p l a n t s c o u l d p r e s e n t l y grow ( K e l l e r h a l s a n d M u r r a y , 1 9 6 9 ) , i n d i c a t i n g s u b m e r g e n c e a t t h i s l o c a t i o n . T h i s p e a t i s d i s c u s s e d f u r t h e r i n 7. UJ z Ul o o - I o X 5500 yrs. 6000 - 9000 Shoreline near present sea-level, minor fluctuations Land about 10m above present sea level Sumas Glaciation Sumas Emergence ~11500 yrs. glaciofluvial, channel, floodplain, 3 deltaic, sand, gravel e» 11500 - 12000 Pre-Sumas Submergence 12000 13000 Post-Vashon Emergence Ice retreated fossiliferous marine sediments terrestrial, deltaic sands and gravels (Armstrong, 1960) 09 J UJ z Ul o o I -w UJ c o o a O o GO (0 Vashon Till Quadra Sand Olympia Nongiacial PLIOCENE - MIOCENE UPPER EOCENE MID EOCENE -UPPER CRETACEOUS MID MESOZOIC Cowichan Head Formation Semiahmoo & Dashwood Drifts Highbury, Mapleguard Sediments Boundary Bay Formation Kitsilano Formation Burrard Formation till, fluvioglacial, ice contact deposits, outwash, sand, gravel (Armstrong, 1977) cross stratified, well sorted white sand, minor gravel and silt, proglacial outwash (Armstrong, 1977; Clague, 1977) parallel bedded, marine, fluvial, estuarine silt, sand, gravel glaciomarine, glaciofluvial gravel, sand, clay, silt, till fluvial, marine, swamp deposits, sand, clay, silt (Fyles, 1963) sandstone, shale, volcanic ash, clay (Hopkins, 1966) conglomerate, sandstone, shale (Hopkins, 1969; Rouse, 1977) conglomerate, sandstone, shale (Blunden, 1975; Crickmay and Pocock 1963,- Rouse et al., 1975) Coast Plutonic Complex emplaced T a b l e 1. Summary o f t h e g e o l o g i c a l h i s t o r y o f the F r a s e r Lev?lands. 8. Chapter 3. Peat bogs dev e l o p e d on the s u r f a c e of the d e l t a , i n d e p r e s -s i o n s formed by former c h a n n e l s , and cover one t h i r d of the sub-a e r i a l d e l t a s u r f a c e ; o t h e r s u r f i c i a l d e p o s i t s i n c l u d e g l a c i a l d r i f t , l a c u s t r i n e , d e l t a i c , and f l u v i a l sands and s i l t s , and s a l t m a r s h d e p o s i t s (Armstrong, 1956, 1957, 1960, 1979, 1980). In Burns Bog, a s h o r t s a l t marsh phase dev e l o p e d above d e l t a f r o n t s i l t y sands commencing at 4125±110 y r s B.P. (Hebda, 1977). P e a t s f o r m i n g L u l u I s l a n d bogs commenced fo r m i n g 4685±95 y e a r s B.P. ( T e l e d y n e , 1-11, 742) and are b e i n g s t u d i e d by S t y a n , 1981. The Study Area Boundary Bay may be d e s c r i b e d as a headland-bay beach (Yasso, 1965, L e B l o n d , 1979); i t i s 15 km l o n g and 4 km wide, w i t h a s u r f a c e a r e a of 61 km2 ( F i g u r e 2 ) . The Bay i s p r o t e c t e d from w e s t e r l y and s o u t h w e s t e r l y winds by the P o i n t R o b e r t s P e n i n s u l a . The S e r p e n t i n e and N i c o m e k l R i v e r s f l o w i n t o the n o r t h e a s t c o r n e r , known as Mud Bay, and s m a l l , ephemeral streams e n t e r i t from the west. The a r e a has a m o d i f i e d West Coast m a r i t i m e c l i m a t e , w i t h m i l d , wet w i n t e r s and d r y , warm, b r i g h t summers. The c l i m a t e i s d e s c r i b e d as a Koeppen Csb M e d i t e r r a n e a n - t y p e c l i m a t e (Hoos and Packman, 1974). M e t e o r o l o -g i c a l r e c o r d s taken a t Ladner, 5 km northwest of the 64th S t r e e t a r e a , show an average of 903 mm of p r e c i p i t a t i o n a y e a r , i n c l u d -i n g 34 cm of snow; most r a i n f a l l s i n December and l e a s t i n J u l y . The a n n u a l average temperature i s 9.4°C, the J u l y mean Dyke F i g u r e 2. Map o f Boundary Bay showing l o c a t i o n s of the study areas (modified a f t e r Swinbanks, 19 79). 10. b e i n g 1 6 . 7 ° C a n d t h e J a n u a r y mean, 2 . 2 ° C . ( B r i t i s h C o l u m b i a D e p a r t m e n t o f A g r i c u l t u r e , 1 9 7 1 ) . P r e v a i l i n g w i n d s come f r o m t h e e a s t a n d s o u t h e a s t , a n d h u m i d i t y i s h i g h t h r o u g h o u t t h e y e a r (Hoos a n d Packman, 1 9 7 4 ) . T h e t i d e s i n B o u n d a r y Bay a r e a m i x e d s e m i d i u r n a l t y p e , w i t h two h i g h a n d two low w a t e r s e a c h d a y . S u c c e s s i v e h i g h a n d low w a t e r s a r e o f d i f f e r e n t h e i g h t s ( W e i r , 1 9 6 0 ) . T i d e s e n t e r t h e Bay f r o m t h e s o u t h , t h e f l o o d t i d e b e i n g more c o n c e n t r a t e d on t h e e a s t s i d e a n d t h e e b b more c o n c e n t r a t e d on t h e w e s t s i d e ( W e i r , 1 9 6 0 ) . T h e h i g h e s t mean s p r i n g t i d a l r a n g e i s a b o u t 3 m, w i t h t h e mean t i d a l r a n g e b e i n g 2.7 m a n d t h e mean n e a p t i d a l r a n g e b e i n g 1 . 5 m ( W e i r , 1 9 6 0 ) . The w a t e r i n t h e Bay i s c l e a r , a n d h a s a s a l i n i t y o f 24 t o 29 p e r m i l , s i m i l a r t o t h a t o f t h e S t r a i t o f G e o r g i a ( S w i n b a n k s , 1 9 7 9 ) . The s u r f a c e s e d i m e n t s i n t h e Bay h a v e b e e n ' d e s c r i b e d by K e l l e r h a l s a n d M u r r a y ( 1 9 6 9 ) a n d S w i n b a n k s ( 1 9 7 9 ) , a n d i n c l u d e g r a v e l , s a n d , s i l t y s a n d , mud, p e a t , a n d a c c u m u l a t i o n s o f s h e l l s a n d d r i f t w o o d . The g r a i n s i z e o f t h e s u r f a c e s e d i m e n t s i n m o s t l o c a l i t i e s v a r i e s l i t t l e , h o w e v e r , b e i n g m a i n l y v e r y f i n e t o f i n e s a n d w h i c h shows a g r a d u a l s h o r e w a r d f i n i n g t r e n d ( S w i n b a n k s , 1 9 7 9 ) . D e t r i t a l s e d i m e n t s i n B o u n d a r y Bay come l a r g e l y f r o m t h e e r o s i o n o f t h e P l e i s t o c e n e c l i f f s a t P o i n t R o b e r t s ; l e s s e r a m o u n t s a r e d e r i v e d f r o m t h e e r o s i o n o f t h e s a l t m a r s h a t Mud B a y . The S e r p e n t i n e a n d N i c o m e k l R i v e r s b r i n g some s i l t a n d c l a y i n t o t h e e a s t e r n p a r t o f t h e B a y . S e d i m e n t i s t r a n s p o r t e d i n t h e Bay by l o n g s h o r e d r i f t ( S w i n b a n k s , 1 9 7 9 ) . The t i d a l .11. f l a t s a r e d r a i n e d by c r e e k s . The b e d r o c k b e n e a t h B o u n d a r y Bay i s t h e P l i o c e n e / M i o c e n e B o u n d a r y Bay F o r m a t i o n . I n a 1250 m d e e p w e l l ( B o u n d a r y Bay W e l l No. 3 ( J o h n s t o n , 1 9 2 3 ) ) , 700 m o f P l e i s t o c e n e a n d R e c e n t d e p o s i t s were p e n e t r a t e d , w i t h t h e u n d e r l y i n g s e d i m e n t s c o n s i s -t i n g o f p o o r l y c o n s o l i d a t e d s a n d s , s h a l e s , l i g n i t e s , c o n g l o m e r -a t e s , a n d g r a v e l s o f P l i o c e n e - M i o c e n e a g e ( H o p k i n s , 1 9 6 6 ) . P r i o r t o t h e c o n s t r u c t i o n o f t h e d y k e s , t h e l o w - l y i n g l a n d a d j a c e n t t o B o u n d a r y Bay was f r e q u e n t l y i n u n d a t e d by w i n t e r a n d s p r i n g h i g h t i d e s , s o m e t i m e s a s s o c i a t e d w i t h t h e F r a s e r R i v e r f r e s h e t . L a n d was commonly u n d e r w a t e r f o r up t o s i x m o n t h s o f t h e y e a r ( H o w i e a n d S c h o l f i e l d , 1 9 1 4 , i n T a y l o r , 1 9 5 8 ) . F a r m e r s b u i l t d y k e s a r o u n d t h e i r own l a n d , b u t f o l l o w i n g t h e G r e a t F l o o d i n 1894, w h i c h was a s s o c i a t e d w i t h t h e F r a s e r R i v e r f r e s h e t i n May a n d J u n e a n d w h i c h c o v e r e d t h e l a n d w i t h 0.6 t o 1 m o f w a t e r , D e l t a M u n i c i p a l i t y u n d e r t o o k d y k i n g ( T a y l o r 1958; T e r r i s 1 9 7 3 ; L a d n e r 1 9 7 9 ) . The f i r s t d y k e was b u i l t a l o n g B o u n d a r y Bay i n 1 895, a n d t h e d y k e s were l a t e r s t r e n g t h e n e d a n d h e i g h t e n e d i n 1948, f o l l o w i n g t h e F r a s e r V a l l e y f l o o d . The F r a s e r R i v e r D e l t a i s i n t h e w e t t e r s u b z o n e o f t h e C o a s t a l D o u g l a s - F i r B i o g e o c l i m a t i c z o n e o f B r i t i s h C o l u m b i a ( K r a j i n a , 1 9 6 9 ) ; t h i s v e g e t a t i o n i s p r e s e n t on u p l a n d a r e a s . Some n a t u r a l v e g e t a t i o n h a d b e e n c l e a r e d f o r f a r m i n g , by b e a -v e r s , a n d by f i r e ( N o r t h e t a l . , 1979) p r i o r t o 1858, when t h e l a n d was f i r s t s u r v e y e d . B e t w e e n 1858 a n d 1880, t h e d r i f t r i d g e s were f o r e s t e d ; B u r r a r d P e n i n s u l a a n d t h e S u r r e y U p l a n d s p o s s e s s e d a v e g e t a t i o n o f c o n i f e r o u s , s c r u b , a n d d e c i d u o u s 1 2 . f o r e s t , w h i l s t t h e B l a i n e U p l a n d s a n d P o i n t R o b e r t s P e n i n s u l a were v e g e t a t e d by c o n i f e r o u s a n d l e s s e r a m o u n t s o f d e c i d u o u s f o r e s t . T h e l o w l a n d s o f t h e d e l t a were d o m i n a n t l y g r a s s p r a i r i e , w i t h some t r e e s on h i g h e r a r e a s a n d s h r u b s a n d m o s s e s c o v e r i n g t h e l a r g e b o g s . Some s a l t m a r s h d e v e l o p m e n t o c c u r r e d a r o u n d B o u n d a r y Bay, e x t e n d i n g i n l a n d f r o m t h e s e a . The s e a w a r d e x t e n t o f t h e s a l t m a r s h i s n o t shown on e a r l y maps. R a d i o c a r b o n d a t e s s u g g e s t t h a t t h e s a l t m a r s h a t 6 4 t h S t r e e t was i n i t i a t e d a b o u t 3 4 5 ± 7 5 y e a r s B.P. ( T e l e d y n e , 1-11, 7 6 4 ) . I t may h a v e e x t e n d e d n o r t h w a r d s f r o m t h e Bay, b u t b e i n g a s u r f i c i a l d e p o s i t , w o u l d h a v e b e e n p l o u g h e d a n d d e s t r o y e d when f a r m i n g b e g a n . The t i d a l f l a t s a t B o u n d a r y Bay h a v e b e e n s u b d i v i d e d i n t o d i f f e r e n t z o n e s by p r e v i o u s w o r k e r s . K e l l e r h a l s a n d M u r r a y ( 1 9 6 9 ) r e c o g n i z e d f o u r m a i n s e d i m e n t o l o g i c - h y d r o l o g i c d i v i s i o n s o f t h e t i d a l f l a t s , e a c h p o s s e s s i n g d i s t i n c t d r a i n a g e p a t t e r n s , s e d i m e n t a r y s t r u c t u r e s , a n d f l o r a l a n d f a u n a l a s s e m b l a g e s . S w i n b a n k s ( 1 9 7 9 ) r e v i s e d t h e i r z o n a t i o n , e s t a b l i s h i n g f i v e z o n e s d e l i m i t e d by e l e v a t i o n a n d e x p o s u r e ( i n r e l a t i o n t o c r i t i c a l t i d e l e v e l s ) , e a c h w i t h a d i s t i n c t i v e f l o r a a n d f a u n a . The m a i n p o i n t s o f e a c h scheme a r e s u m m a r i z e d on F i g u r e 3. T h i s s t u d y c o n c e n t r a t e s on a s a l t m a r s h w h i c h h a s d e v e l o p e d on t h e t i d a l f l a t s a t 6 4 t h S t r e e t a n d i s b o u n d e d l a n d w a r d by a d y k e ( F i g u r e 2 ) . The s a l t m a r s h i s up t o 600 m w i d e i n t h e w e s t o f t h e Bay, b u t becomes v e r y n a r r o w a n d l o c a l l y d i s a p p e a r s t o t h e e a s t ( K e l l e r h a l s a n d M u r r a y , 1 9 6 9 ) . T h e m a r s h t o t h e w e s t i s t h o u g h t t o be p r o g r a d i n g o v e r t h e t i d a l f l a t s , a s s e e n by EXPOSURE ZONE Atmozone Atm°o"one U p p e r A m P h i 2 0 n e Lower Amphizone Upper Aquazone Lower Aquazone SEDIMENTS sand, peat, silt, clay very fine sand very fine - fine sand fine sand SEDIMENTARY STRUCTURES irregular stratification algal laminae low amplitude symmetrical waves lunate and straight crested sand waves, ripples, dunes in channels FLORA mesophytes halophytes c c yanophyti hlorophyt 38 38 Zostera americana Zostera marina Zostera marina in channels FAUNA Hemigraspus Batillarla Spio Abarenlcola. Mya. Callianassa Up_oge bia. Praxillela, Nassarius Praxilla, Nassarius, sand dolla rs 1.5 " S ~ 1.0-tS 1 -0.5 -•§ o-z" o -0.5 -Q .% i.o-£ g 1.5-12 2 .0-m . 2.5-SALTMARSH SALTMARSH ALGAL MAT HIGH TI SWINBANKS, 1979 UPPER SA DAL FLATS ND WAVE INTERME TIDAL F DIATE LATS EELGRASS .••.LOW TIDAL FLATS S LOV VER SAND WAVE KELLERHALS and MURRAY, 1969 DRAINAGE meandering tidal creeks irregular incomplete well developed dendritic deeper, more stable channels SEDIMENTS silty, sandy, peat, driftwood fine - medium sand SEDIMENTARY STRUCTURES poor stratification symmetrical ripples, algal laminations asymmetrical ripples dunes in channels FLORA halophytes blue-green algae Zostera, Ulva FAUNA Mya, Mytilus, Cerlthium. Hemigraspus Callianassa. Mya. Cerlthium. Mytilus, Balanva Callianassa. Abarenlcola. Ostrea Dendraster, Pisaster, Anthopleura. Cancer, Pugettia, polychaetes. clams F i g u r e 3. Summary o f the s u b d i v i s i o n s o f the Boundary Bay t i d a l f l a t s , a c c o r d i n g t o Swinbanks .and . KPTI l e r h a l s and Murray. 14. f o r m e r b e a c h r i d g e s c o n s i s t i n g o f l o g s b e i n g o v e r g r o w n by v e g e -t a t i o n , w h e r e a s i n t h e e a s t , c l i f f s a t t h e s e a w a r d e d g e o f t h e m a r s h a n d t h e p r e s e n c e o f a p a r t l y b u r i e d o l d e r p e a t i n d i c a t e s e r o s i o n a n d r e d e p o s i t i o n ; a 1200 m r e c e s s i o n i n t h e s a l t m a r s h s i n c e 4 3 5 0 ± 1 0 0 y e a r s B.P. ( GX-0781) was c a l c u l a t e d by K e l l e r h a l s a n d M u r r a y ( 1 9 6 8 ) b a s e d on t h e p o s i t i o n o f p r e s e n t d a y s a l t m a r s h e s r e l a t i v e t o t h e s h o r e l i n e . The s a l t m a r s h d e v e l o p i n g t o d a y i n t h e w e s t p a r t o f • B o u n d a r y Bay a p p e a r s t o be a t y p i c a l s i m p l e P a c i f i c c o a s t s a l t m a r s h (Chapman, 1960; M a c D o n a l d a n d B a r b o u r , 1 9 7 4 ) . M o s t s a l t m a r s h e s d e c r e a s e i n h e i g h t f r o m t h e l a n d t o w a r d s t h e s e a , a c c o m -p a n i e d by c h a n g e s i n t h e v e g e t a t i o n . T h e l o w e r p a r t o f t h e m a r s h i s s u b j e c t t o f r e q u e n t t i d a l i n u n d a t i o n s , w h i l s t t h e u p p e r p a r t i s r a r e l y f l o o d e d . The s a l t m a r s h a t 6 4 t h S t r e e t a p p e a r s t o c o n f o r m t o t h e s e s p e c i f i c a t i o n s . 15. CHAPTER 2: METHODS F i e l d Methods A s e r i e s of e l e v e n c o r e s was o b t a i n e d from the s a l t marsh at 64th S t r e e t ( F i g u r e 4) and t h r e e from 112th S t r e e t ( F i g u r e 5 ) . C o r i n g w i t h a H i l l e r c o r e r , a v i b r o c o r e r , and a t r u c k -mounted c o r e r were u n s u c c e s s f u l l y t r i e d . D i g g i n g a l a r g e h o l e and s a m p l i n g the s i d e s proved t o be the most s u c c e s s f u l method. Samples were c o l l e c t e d i n 30 cm l e n g t h s and were wrapped i n a l u -minum f o i l . The upper, f r i a b l e p e a t s were sub-sampled at 5 cm i n t e r v a l s and put i n t o p l a s t i c bags i f they were v e r y u n c o n s o l i -d a t e d . Samples f o r r a d i o c a r b o n d a t i n g were wrapped t w i c e i n aluminum f o i l , p l a c e d i n p l a s t i c bags, and f r o z e n upon r e t u r n i n g t o the l a b o r a t o r y . Twelve p o l l e n t r a p s were m o n i t o r e d from 1.5.80 t o 30.11.80 at v a r i o u s l o c a t i o n s over the s a l t marsh at 64th S t r e e t ( F i g u r e 4 ) . Cores were o b t a i n e d from ar e a s a d j a c e n t t o the p o l l e n t r a p s . G l a s s j a r s , w i t h a t h i n f i l m of g l y c e r i n e i n the bottom t o p r e v e n t g r a i n s b e i n g blown out of the j a r s and c o v e r e d w i t h a 1.42 mm s c r e e n , were sunk i n the ground so t h a t o n l y 2 cm p r o t r u d e d . The j a r s were emptied r e g u l a r l y . Modern p o l l e n was c o l l e c t e d from the v a r i o u s s p e c i e s (Table 2) on the s a l t marsh, the s p e c i e s b e i n g i d e n t i f i e d by use of H i t c h c o c k and C r o n g u i s t (1973). 16. F i g u r e 4. The s a l t marsh at 64th S t r e e t , showing s t a t i o n l o c a t i o n s and the v e g e t a t i o n zones. F i g u r e 5. Map showing l o c a t i o n o f the cores o b t a i n e d n e ar 112th S t r e e t . SaBcornia, Grindela, grasses, some Atrip lex and Vicia Atrip lex on strandline Grindelia, Salicornia, Juncus  Plantaoo, Triglochin, Distichl  Spergularia, Cuscuta Triglochin algal mat zone • 10 SCALE, metres 50 0 50 100 1! Table 2. V e g e t a t i o n found at 64th S t r e e t . CARYOPHYLLACEAE S p e r g u l a r i a marina L. CHENOPODIACEAE A t r i p l e x p a t u l a L. S a l i c o r n i a v i r q i n i c a L. COMPOSITAE A c h i I l e a mi l i e f o l i u m L. Aqoser i s sp. Raf. Aster s u b s p i c a t u s Nees. Gr i n d e l i a i n t e g r i f o l i a D.C. Solidago sp. L. CUSCUTACEAE Cuscuta s a l i n a Engelm. GRAMINEAE Agropyron sp. Gaertn. A g r o s t i s sp. L. D i s t i c h l i s s p i c a t a L. Elymus m o l l i s T r i n . Puce i n e l l i a sp. P a r i . JUNCACEAE Juncus b a i t i c u s W i l l d . JUNCAGINACEAE T r i g l o c h i n maritimum L. LEGUMINOSAE V i c i a sat i v a L. MALVACEAE S i d a l c e a hendersoni Wats. PLANTAGINACEAE Plantaqo maritima L. POLYGONACEAE Rumex c r i s p u s L. ROSACEAE Malus fusca Raf. UMBELLIFEREAE Ange l l e a l u c i d a L. ZOSTERACEAE Zostera mar ina L. Zostera nana Roth. sandspurry orache, greasewood, s a l t b u s h samphire, glasswort, s a l t w o r t yarrow, m i l f o i l f a l s e dandelion a s t e r gumweed, resinweed goldenrod saltmarsh dodder quackgrass bentgrass s a l t g r a s s dune grass, lime grass a l k a l i grass rush arrow grass common vetch marsh mallow seaside p l a n t a i n c u r l e d dock, s o r r e l P a c i f i c w i l d crabapple a n g e l i c a e e l g r a s s e e l g r a s s L a b o r a t o r y M e t h o d s T h e c o r e s were d i v i d e d i n t o 5 cm i n t e r v a l s a n d 10 cm 3 o f e a c h i n t e r v a l was t a k e n f o r p a l y n o l o g i c a l p r o c e s s i n g . M e c h a n i -c a l m a c e r a t i o n was n o t r e q u i r e d , a s t h e s e d i m e n t s were u n c o n s o -l i d a t e d . T h e d o m i n a n t l y s a n d y s e d i m e n t s were p r o c e s s e d d i f f e r e n t l y f r o m t h e p e a t y s a m p l e s . A d r o p o f c o l d HC1 was a d d e d t o t h e s a n d y s e d i m e n t s t o t e s t f o r t h e p r e s e n c e o f c a l c i u m c a r b o n a t e ; n o n e was d e t e c t e d i n a n y o f t h e s a m p l e s . A f t e r w a s h i n g i n w a t e r , t h e s a m p l e was p u t i n t o 300 ml o f 4 8 % HF i n a t e f l o n b e a k e r a n d m a g n e t i c a l l y s t i r r e d f o r t w e l v e h o u r s t o d i s s o l v e s i l i c a t e s . A f t e r l e t t i n g t h e s e d i m e n t s e t t l e , t h e HF was s i -p h o n e d o f f , a n d t h e s a m p l e w a s h e d t h r e e t i m e s i n w a t e r . T h e s a m p l e was t h e n b o i l e d i n 6 M H C l t o d i s s o l v e f e r r i c c o m p o u n d s . A f t e r w a s h i n g , a known number o f t a b l e t s c o n t a i n i n g L y c o p o d i u m  c l a v a t u m * was a d d e d t o a c t a s an i n t e r n a l s t a n d a r d f o r c a l c u l a -t i n g a b s o l u t e f r e q u e n c i e s ( S t o c k m a r r , 1 9 7 1 ; H e b d a , 1 9 7 7 ) . T h e . t a b l e t s were d i s p e r s e d i n H C l p r i o r t o b e i n g a d d e d t o t h e sam-p l e s . A c e t o l y s i s was p e r f o r m e d , u s i n g a m i x t u r e o f n i n e p a r t s 97% a c e t i c a n h y d r i d e a n d one p a r t 18 M s u l p h u r i c a c i d , f o r t e n m i n u t e s , t o remove c e l l u l o s e a n d o t h e r o r g a n i c m a t e r i a l . T h e s a m p l e s were t h e n o x i d i z e d i n 5% s o d i u m h y p o c h l o r i t e , i f n e c e s -s a r y , a n d s c r e e n e d t h r o u g h a 10 pm s i e v e t o remove f i n e b l a c k m i n e r a l m a t t e r w h i c h p e r s i s t e d i n t h e s a m p l e s . T h e y w e r e t h e n * T a b l e t s obtained from Dr. J . Stockmarr, G e o l o g i c a l Survey of Denmark. These are no longer a v a i l a b l e from t h i s source, but may be obtained from Dr. B.E. Berglund, Department of Quaternary Geology, Tormavagen-13, Lund, Sweden. 21. s c r e e n e d t h r o u g h a 100 m s i e v e , a n d s l i d e s c o n t a i n i n g t h e c o a r -s e r a n d f i n e r f r a c t i o n s were made, u s i n g " K l e e r m o u n t T o l u e n e S o l u t i o n " a s a m o u n t i n g medium. T h i s was done a s t h e c o a r s e o r g a n i c r e m a i n s f r e q u e n t l y o b s c u r e d t h e p o l l e n a n d s p o r e s . . T h e s a m p l e s were s t a i n e d i n a 0.05% s a f r a n i n s o l u t i o n a n d a d d i t i o n a l s l i d e s made. The p e a t s a n d p e a t y s e d i m e n t s w e r e f i r s t b o i l e d i n 5% KOH f o r t e n m i n u t e s t o remove l i g n i n a n d woody t i s s u e , a n d t h e n were s c r e e n e d t h r o u g h a 1.42 mm s i e v e . HC1 a n d HF were u s e d i f m i n -e r a l m a t t e r was p r e s e n t , a n d t h e p r o c e s s c o n t i n u e d a s o u t l i n e d a b o v e f o r s a n d y s a m p l e s . A minimum o f . 200 p o l l e n g r a i n s p e r s a m p l e was c o u n t e d i n two t r a v e r s e s o v e r t h e s l i d e , a n d p o l l e n d i a g r a m s c o n s t r u c t e d f o r t h e c o r e s . T h e t o t a l number o f p o l l e n g r a i n s i n a s a m p l e was c a l c u l a t e d u s i n g L y c o p o d i u m a s an i n t e r n a l s t a n d a r d , a n d t h e f o l l o w i n g f o r m u l a ( S t o c k m a r r , 1 9 7 1 ) : No. o f L y c o p o d i u m s p o r e s a d d e d x No. o f p o l l e n g r a i n s c o u n t e d ( 1 0 , 8 5 0 p e r t a b l e t ) No. o f L y c o p o d i u m s p o r e s c o u n t e d = t o t a l number o f p o l l e n g r a i n s i n a s a m p l e T h e t r a p p e d m a t t e r o b t a i n e d f r o m t h e p o l l e n t r a p s was w a s h e d i n w a t e r , t r e a t e d w i t h 48% HF, a n d a c e t o l i z e d f o r t h r e e m i n u t e s . S l i d e s were t h e n made, u s i n g t h e same p r o c e d u r e a s f o r t h e c o r e s a m p l e s . I f much m i n e r a l m a t t e r was p r e s e n t , s u c h a s i n t h o s e j a r s f r o m t h e i n t e r t i d a l z o n e s , t h e y were b o i l e d i n 6 M HC1 a f t e r HF, s i e v e d , a n d b l e a c h e d . F i n a l l y , Z n B r 2 s o l u t i o n , w i t h a d e n s i t y o f 2.4 g cm" 3 was u s e d t o f l o a t o r g a n i c s f r o m t h e m i n e r a l m a t t e r . 22 . The modern p o l l e n were processed using a c e t o l y s i s and mi-croscope s l i d e s of each species prepared for i d e n t i f i c a t i o n of p o l l e n recovered from the cores. S e l e c t e d p o l l e n g r a i n s were examined with the Scanning E l e c t r o n Microscope ( F i g u r e s 6, 7 and 8). A modern p o l l e n and spore c o l l e c t i o n , prepared from P a c i f i c Northwest s p e c i e s , was used to i d e n t i f y remaining palynomorphs. 23. F i g u r e 6. A g o s e r i s sp. S.E.M. Photograph, ( s c a l e bar r e p r e s e n t s 2^ um) . ! 2 4 F i g u r e 7. G r i n d e l i a i n t e g r i f o l i a . S.E.M. Photograph. / ) F i g u r e 8. A s t e r s u b s p i c a t u s . S.E.M. Photograph. 26. 2 7 . P o l l e n a n d S p o r e I d e n t i f i c a t i o n The two common s a l t m a r s h c h e n o p o d s , S a l i c o r n i a v i r g i n i c a a n d A t r i p l e x p a t u l a ( F i g u r e 9) b o t h p o s s e s s s p h e r o i d a l , p e r i -p o r a t e p o l l e n r a n g i n g f r o m 23 t o 27 ym i n d i a m e t e r . The m a i n d i s t i n g u i s h i n g c h a r a c t e r i s t i c i s p o r e d i a m e t e r , w h i c h i s g r e a t e r t h a n 2 ym i n S a l i c o r n i a v i r g i n i c a , b u t l e s s t h a n 2 ym i n A t r i p l e x p a t u l a , a v e r a g i n g a t 1.6 ym. A l s o , t h e i n t e r p o r e d i s -t a n c e i s 4 t o 6 ym i n S a l i c o r n i a v i r g i n i c a c o m p a r e d t o 3 t o 7 ym i n A t r i p l e x p a t u 1 a . F u r t h e r m o r e , t h e e x i n e o f S a l i c o r n i a  v i r g i n i c a i s t h i n n e r , b e i n g 1.2 t o 1.5 ym, w i t h r e l a t i v e l y i n d i -s t i n c t c o l u m e l l a e , w h e r e a s t h e w a l l o f A t r i p l e x p a t u l a i s 1.9 t o 2.1 ym t h i c k , w i t h a m o d e r a t e c o l u m e l l a t e s t r u c t u r e . The p o l l e n o f C u s c u t a s a l i n a ( C u s c u t a c e a e ) a n d S p e r q u l a r i a  m a r i n a ( C a r y o p h y l l a c e a e ) a r e q u i t e s i m i l a r , b e i n g t r i c o l p a t e w i t h r e t i c u l a t e s c u l p t u r e ( F i g u r e 9 ) . T h e y a r e d i s t i n g u i s h a b l e on t h e b a s i s o f s i z e ; C. s a l i n a i s l a r g e r (22 t o 28 ym; a v e r a g e 23.8 ym) t h a n S. m a r i n a (21 t o 26 ym; a v e r a g e 22.6 y m ) . A few s t e p h a n o c o l p a t e S. mar i n a g r a i n s were a l s o o b s e r v e d . G r a m i n e a e p o l l e n , b e i n g s p h e r o i d a l a n d m o n o p o r a t e , w e r e s t u d i e d f r o m many g r a s s e s , b u t no d i s t i n g u i s h i n g c r i t e r i a c o u l d be f o u n d i n m o s t . P o l l e n o f E l y m u s m o l l i s ( F i g u r e 9 ) , h o w e v e r , were i d e n t i f i a b l e by s i z e , g r a i n s b e i n g 45 t o 62 ym i n d i a m e t e r ( a v e r a g e 51.5 ym), w i t h a d e n s e g r a n u l a t e o r n a m e n t a t i o n . T h e r e m a i n i n g g r a s s p o l l e n a r e l e s s t h a n 42 ym i n d i a m e t e r , a n d were g r o u p e d i n t h e c o u n t s . S i d a l c e a h e n d e r s o n i ( M a l v a c e a e ) h a s d i s t i n c t i v e p o l l e n 28. F i g u r e 9. S e l e c t e d p o l l e n g r a i n s from the s a l t marshc v e g e t a t i o n . a. S a l i c o r n i a v i r g i n i c a (x 1000). b. A t r i p l e x p a t u l a (x 1000). c. Cuscuta s a l i n a (x 1000). d. S p e r g u l a r i a marina (x 1000). e. A s t e r s u b s p i c a t u s (x 1000). f . S o l i d a g o sp. (x 1000). g- A c h i l l e a m i l l e f o l i u m (x 1000). h. G r i n d e l i a i n t e g r i f o l i a (x 1000) . i . Elymus m o l l i s (x 1000) . j • D i s t i c h l i s s p i c a t a (x 1000). k. Plantago m a r i t i m a (x 1000). 1. S i d a l c e a h e n d e rsoni (x 500). m. T r i g l o c h i n maritimum (x 1000). n. A n g e l i c a l u c i d a (x 1000). o. Juncus b a l t i c u s (x 1000). P- A g o s e r i s sp. (x 1000). 30. ( F i g u r e 9 ) ; g r a i n s a r e s p h e r o i d a l , p e r i p o r a t e , e c h i n a t e , a n d 77 t o 90 ym i n d i a m e t e r ( a v e r a g e 84.5 y m ) , i n c l u d i n g s p i n e s t h a t a r e 7 t o 8 ym l o n g . I d e n t i f i c a t i o n o f t h e C o m p o s i t a e was d i f f i c u l t , a s a l l t h e p o l l e n g r a i n s a r e t r i c o l p o r a t e a n d e c h i n a t e . A q o s e r i s s p . g r a i n s ( F i g u r e s 6 a n d 9) r a n g e f r o m 40 t o 45 um i n d i a m e t e r ( a v e r a g e 43.8 ym), a n d t h e e x i n e c o n s i s t s o f d e p r e s s i o n s ( l a -c u n a e ) s e p a r a t e d by h i g h r i d g e s ( m u r i ) w i t h s u p r a - t e c t a l s p i n e s . T h e o t h e r c o m p o s i t e p o l l e n , o f G r i n d e l i a i n t e q r i f o l i a , A s t e r  s u b s p i c a t u s , S o l i d a g o s p . , a n d A c h i l l e a m i l l e f o l i u m a r e s p h e r i -c a l a n d e c h i n a t e . G. i n t e g r i f o l i a c a n be d i s t i n g u i s h e d f r o m t h e o t h e r s by i t s l a r g e r s i z e , a v e r a g i n g 34 ym, i n c l u d i n g s p i n e s ( F i g u r e s 7 a n d 9 ) . The c o l u m e l l a e e x t e n d i n t o t h e s p i n e s f o r a b o u t 1 ym a n d b e a d s a r e p r e s e n t a r o u n d t h e r i m o f t h e p o r e . A s t e r i s 28 t o 30 ym ,in d i a m e t e r , i n c l u d i n g s p i n e s . The e x i n e i s c o l u m e l l a t e a n d r e t i c u l a t e ( F i g u r e s 8 .and 9 ) . S o l i d a g o a n d A c h i I l e a w e r e g r o u p e d , a s no d i s t i n g u i s h i n g c r i t e r i a w ere o b -s e r v e d ; a l s o , s e p a r a t i o n o f t h e s e two was n o t f e l t t o be c r i t i -c a l , b e c a u s e t h e y o c c u r t o g e t h e r on t h e m o s t e m e r g e n t p a r t o f t h e s a l t m a r s h . B o t h p o l l e n h a v e a t h i c k , h e a v y e x i n e a n d a r e 27 t o 30 um i n d i a m e t e r . CHAPTER 3: RESULTS The S a l t Marsh at 64th S t r e e t D i s t i n c t i v e changes in the v e g e t a t i o n of the s a l t marsh can be observed i n a seaward d i r e c t i o n from the dyke. The upper, emergent part of the marsh has been c o l o n i z e d by mesophytes, whereas halophytes dominate the v e g e t a t i o n in the lower, submer-gent p a r t . The zonation of the v e g e t a t i o n i s due to changes in e l e v a t i o n r a ther than time (Figure 4). Di s t r i b u t ion of Veqetat ion The most landward part of the s a l t marsh near the dyke pos-sesses a v e g e t a t i o n of Maius f u s c a , Solidago sp., S i d a l c e a  hendersoni, Agoser i s sp., Aster s u b s p i c a t u s , A c h i I l e a  m i l l e f o l i u m , Juncus b a l t i c u s , and grasses (Figure 10). S o l i d a g o sp. and Juncus b a l t i c u s are not present at S t a t i o n x l - they occur only c l o s e r to the dyke. Around S t a t i o n 1, i s o l a t e d p l a n t s of A n g e l i c a l u c i d a and Rumex c r i s p u s are found. Malus  fus c a , S i d a l c e a hendersoni, and A g o s e r i s sp. do not occur sea-ward of t h i s zone, except f o r a small patch of A g o s e r i s sp., which occurs with A n g e l i c a luc ida at S t a t i o n 3a. Grasses dominate the v e g e t a t i o n at S t a t i o n 2, i n c l u d i n g i s o l a t e d patches of Elymus m o l l i s . A small channel ( i n which S t a t i o n 2a was l o c a t e d ) , c o n t a i n i n g d r i f t w o o d , possesses a v e g e t a t i o n that con-t r a s t s with the adjacent areas ( F i g u r e s 4 and 11). In the channel,the main s p e c i e s are Gr i n d e l i a i ntegr i f o l i a and D i s t i c h l i s s p i c a t a , with l e s s e r amounts of S a l i c o r n i a v i r g i n i c a , F i g u r e 10. The most landward p a r t of the s a l t marsh near the dyke ( s c a l e i s 30 cm). F i g u r e 11. The channel by S t a t i o n 2a, i n which D i s t i c h l i s  s p i c a t a , G r i n d e l i a i n t e g r i f o l i a and S a l i c o r n i a v i r g i n i c a grow. w h i l s t a r o u n d t h e c h a n n e l t h e m a i n p l a n t s a r e A s t e r ' s u b s p i c a t u s , Rumex c r i s p u s , A c h i I l e a m i l l e f o l i u m , w i t h s p o r a d i c G r i n d e l i a  i n t e g r i f o l i a , E l y m u s m o l l i s, a n d o t h e r g r a s s e s . T h i s c h a n n e l f i l l e d w i t h s e a w a t e r i n t h e w i n t e r o f 1 9 8 0 - 1 9 8 1 , a n d t h e v e g e t a -t i o n i n i t r e p r e s e n t s a l e s s e m e r g e n t z o n e c o m p a r e d t o t h e s u r -r o u n d i n g v e g e t a t i o n i n t h a t t h e p l a n t s can. t o l e r a t e p e r i o d i c s u b m e r g e n c e s by m a r i n e w a t e r s . A t S t a t i o n 3a, t h e r e i s a l o c a l i z e d c i r c u l a r z o n e o f J u n c u s  b a i t i c u s , A n g e l i c a l u c i d a , a n d A g o s e r i s s p . The r e a s o n f o r t h i s z o n e d e v e l o p i n g h e r e i s unknown, b u t may be r e l a t e d t o a t o p o -g r a p h i c h i g h i n t h e u n d e r l y i n g s i l t s . S e a w a r d o f S t a t i o n 3 i s a z o n e c o v e r e d i n d r i f t w o o d w a s h e d i n by s t o r m s ; t h e v e g e t a t i o n i s l e s s d i v e r s e t h a n a t S t a t i o n s 1 a n d 2. A s t e r s u b s p i c a t u s , A c h i I l e a m i l l e f o l i u m , E l y m u s m o l l i s , Rumex c r i s p u s , A n g e l i c a  l u c . i d a , a n d A g o s e r i s s p . do n o t grow s e a w a r d o f t h i s p o i n t . S a l i c o r n i a v i r g i n i c a , Gr i n d e l i a i n t e g r i f o l i a , a n d g r a s s e s a l s o grow h e r e , w i t h o c c a s i o n a l p l a n t s o f A t r i p l e x p a t u l a a n d V i c i a  s a t i v a . C u s c u t a s a l i n a , t h e s a l t m a r s h d o d d e r , o c c u r s a s a p a r a -s i t e on h o s t S a l i c o r n i a p l a n t s . T h i s z o n e i s q u i t e e x t e n s i v e , e n d i n g a b r u p t l y s e a w a r d a t t h e u p p e r l i m i t o f t h e s t r a n d l i n e ; b e y o n d t h e s t r a n d l i n e t h e r e a r e no l o g s , b u t s t o r m l i t t e r h a s a c c u m u l a t e d t o f o r m t h i c k m a t s o f e e l g r a s s m i x e d w i t h a l g a e ( F i g u r e 1 2 ) . The s t r a n d l i n e m a r k s t h e t r a n s i t i o n b e t w e e n t h e u p p e r , e m e r g e n t , more e s t a b l i s h e d m a r s h , w i t h a t h i c k e r p e a t , a n d t h e l o w e r , s u b m e r g e n t m a r s h w i t h a t h i n c o v e r o f o r g a n i c r i c h s a n d . A l o n g t h e s t r a n d l i n e , A t r i p l e x p a t u l a g r o w s l u -x u r i a n t l y a m o n g s t t h e e e l g r a s s i n a z o n e a b o u t 3 m w i d e ( F i g u r e 13) A t r i p l e x i s o f t e n f o u n d g r o w i n g a l o n g t h e s t r a n d l i n e a s i t s F i g u r e 12. E e l g r a s s , washed i n by storms, around T r i g l o c h i n maritimum ( s c a l e i s 30 cm). 36 , 37. F i g u r e 13. A t r i p l e x p a t u l a growing along the s t r a n d l i n e . The submergent marsh can be seen seaward o f t h i s zone. F i g u r e 14. Halophyte hummocks beyond the seaward edge o f the continuous marsh. 39. s e e d s a r e t r a p p e d i n t h e t i d a l l i t t e r (Chapman, 1976; R a n w e l l , 1 9 7 2 ) ; Hulme ( 1 9 5 7 , _in R a n w e l l , 1972) d e s c r i b e s t h e c o l o n i z a t i o n o f t h i s z o n e by A t r i p l e x on t h e f o r e s h o r e a t L o n g r i d d r y , E a s t L o t h i a n , S c o t l a n d . A s i m i l a r p r o c e s s i s e n v i s a g e d t o o c c u r i n B o u n d a r y B a y . The z o n e s e a w a r d o f t h i s n a r r o w s t r a n d l i n e i s c o l o n i z e d m a i n l y by t h e h a l o p h y t e s S a l i c o r n i a v i r g i n i c a , T r i g l o c h i n  mar i t imum, S p e r g u l a r i a mar i n a , a n d C u s c u t a s a l i n a . I n t h e . p r o -x i m a l p a r t o f t h e z o n e , t h e s e a r e a s s o c i a t e d w i t h D i s t i c h l i s  s p i c a t a , P l a n t a g o mar i t ima, a n d G r i n d e l i a i n t e g r i f o l i a , b u t s e a -w a r d s S a l i c o r n i a v i r g i n i c a a n d T r i g l o c h i n m a r i t i m u m p e r s i s t a l o n e . C u s c u t a s a l i n a was f o u n d on S a l i c o r n i a p l a n t s o n l y s e a -w a r d o f S t a t i o n 4. T h e p i o n e e r p l a n t s o f t h e m a r s h a p p e a r t o be S a l i c o r n i a  v i r g i n i c a a n d T r i q l o c h i n m a r i t i m u m ; i s o l a t e d hummocks c o l o n i z e d by t h e s e h a l o p h y t e s ( F i g u r e 14) a r e f o u n d e x t e n d i n g o u t w a r d f r o m t h e s e a w a r d e d g e o f t h e c o n t i n u o u s m a r s h w h e r e i t e n c r o a c h e s o n t o t h e h i g h t i d a l f l a t s . The h i g h t i d a l f l a t s a r e c o v e r e d by e x t e n s i v e a l g a l m a t s , w h i c h s t a b i l i z e r i p p l e s a n d b i n d w a s h e d - i n e e l g r a s s b l a d e s ( F i g u r e s 15 a n d 1 6 ) . D i s t r i b u t i o n o f M o d e r n P o l l e n P o l l e n a s s e m b l a g e s , c o l l e c t e d a t v a r i o u s l o c a t i o n s o v e r t h e s a l t m a r s h ( F i g u r e 1 7 ) , r e f l e c t t h e g e n e r a l z o n a t i o n o f v e g e t a -t i o n i n t h e m a r s h ( F i g u r e 4 ) , b u t t h e r e a r e some d i s c r e p a n c i e s . T h e n a t u r e o f t h e v e g e t a t i o n , c h a n g i n g f r o m t h e d i v e r s e a s s e m b -l a g e o f m e s o p h y t e s ( A s t e r , S o l i d a g o , A c h i I l e a , S i d a l c e a , F i g u r e 15. A l g a l mats s t a b i l i z i n g r i p p l e s on the h i g h t i d a l f l a t s ( s c a l e i s 30 cm). F i g u r e 16. A l g a l mats b i n d i n g washed-in e e l g r a s s blade 42. Brg 160 N UJ 10 Station No. 100 200 300 400 DISTANCE, m 500 600 700 Triglochin So. li corni a pergularia Solidago-• Achi Ilea Sidalcea Rosaceae Pinus Ps eudotsua a Cupressaceae < A onus Belulc Cory lus Monolete f e r n s P t e r i d i i Lycop odium - i g u r e .17.. P o l l e n a s s e m b i s c = the t r a n s e c from May t o Noveir.ber, 1980, a ^ s f c u l i e c t e d at the S t a t i o n s over on tne s a l t marsh at 64th S t r e e t 43. A q o s e r i s , A n g e l i c a ) a t t h e i n n e r , most e l e v a t e d m a r g i n o f t h e m a r s h , t o a z o n e d o m i n a t e d by g r a s s e s a t S t a t i o n 2, t o t h e A t r i p l e x - c o l o n i z e d s t r a n d l i n e a t S t a t i o n 5, a n d f i n a l l y t o S a l i c o r n i a a n d T r i g l o c h i n a t t h e l o w e s t , s e a w a r d edge o f t h e s a l t m a r s h , c a n be c l e a r l y s e e n i n F i g u r e 17. The c h a n n e l , w i t h G r i n d e l i a a t S t a t i o n 2a, a n d t h e A n g e l i c a - A q o s e r i s z o n e a t S t a t i o n 3a a r e v i s i b l e . H o w e v e r , t h e d i s p e r s a l o f p o l l e n by w i n d a n d w a t e r must be c o n s i d e r e d . A t r i p l e x a p p e a r s t o be more w i d e s p r e a d t h a n i t s s o u r c e z o n e , a s do E l y m u s , T r i g l o c h i n , a n d Rumex. The d i s t r i b u t i o n o f a r b o r e a l p o l l e n shows t h a t t h e y h a v e b e e n d i s p e r s e d by b o t h w i n d a n d w a t e r ; w i n d i s more i m p o r t a n t i n t h e u p p e r m a r s h a n d w a t e r i n t h e l o w e r m a r s h . H i g h c o n c e n t r a -t i o n s o f a r b o r e a l p o l l e n , r e p r e s e n t i n g c o a s t f o r e s t s p e c i e s , a t t h e s e a w a r d e d g e o f t h e m a r s h a r e due t o t h e s e p o l l e n b e i n g a b u n d a n t i n t h e s e a w a t e r o f t h e S t r a i t o f G e o r g i a . I n a d d i t i o n , some were p o s s i b l y t r a n s p o r t e d i n t o t h e Bay by t h e S e r p e n t i n e a n d N i c o m e k l R i v e r s a n d o t h e r s m a l l e r s t r e a m s . A m a r k e d d e -c r e a s e i n c o a s t f o r e s t p o l l e n l a n d w a r d o f S t a t i o n 6 i s a t t r i -b u t e d t o a l a c k o f f r e q u e n t s u b m e r g e n c e o f t h e s a l t m a r s h by m a r i n e w a t e r s . The R o s a c e a e p o l l e n may h a v e b e e n d e r i v e d l a r g e -l y f r o m M a i u s f u s c a g r o w i n g a t t h e i n n e r m a r g i n o f t h e m a r s h . F o r m a t i o n o f t h e S a l t M a r s h T h e s e a w a r d e d g e o f t h e s a l t m a r s h c o n s i s t s o f i r r e g u l a r hummocks, 30-60 cm h i g h , w h i c h h a v e b e e n c o l o n i z e d by h a l o p h y t e s ( F i g u r e 1 4 ) ; t h e f i r s t s u b a e r i a l c o l o n i s t s o f t h e s a n d y t i d a l f l a t s a r e S a l i c o r n i a v i r g i n i c a a n d T r i g l o c h i n m a r i t i m u m ( F i g u r e s 18 a n d 1 9 ) . K e l l e r h a l s a n d M u r r a y ( 1 9 6 9 ) s t a t e t h a t t h e d e v e l -44 F i g u r e 1 8 . P i o n e e r S a l i c o r n i a v i r g i n i c a on t h e h i g h t i d a l f l a t s ( s c a l e i s 30 c m ) . F i g u r e 1 9 . S m a l l T r i g l o c h i n m a r i t i m u m hummock ( s c a l e i s 30 c m ) . 46. opment o f t h e hummocks i s r e l a t e d t o l a r g e a m o u n t s o f a l g a l d e b r i s a n d e e l g r a s s b e i n g r a f t e d i n t o t h e a r e a i n t h e f a l l ; t h e s e a r e c o v e r e d by s a n d d u r i n g t h e w i n t e r , p r o d u c i n g a v e r y u n e v e n s u r f a c e , t h e h i g h p a r t s o f w h i c h a r e s u b s e q u e n t l y c o l o -n i z e d by a l g a e . T h e y s u g g e s t t h a t t h e t r a p p i n g o f s e d i m e n t by t h e a l g a l m a t s i n c r e a s e s t h e amount o f r e l i e f u n t i l i t i s s u f f i -c i e n t l y e l e v a t e d f o r h a l o p h y t e s t o t a k e r o o t a n d t o s u b s e q u e n t l y r a i s e a n d e n l a r g e t h e a r e a e v e n more. As t h e h a l o p h y t e hummocks grow a n d c o a l e s c e , t h e y w o u l d e v e n t u a l l y be w e l d e d o n t o t h e s a l t m a r s h . T h i s p r o c e s s may o c c u r , b u t i s o l a t e d S a l i c o r n i a  v i r g i n i c a a n d T r i q l o c h i n m a r i t i m u m p l a n t s were s e e n t o be g row-i n g d i r e c t l y on t h e t i d a l f l a t s , a p p a r e n t l y u n r e l a t e d t o a l g a l mat mounds. T h e s e p i o n e e r h a l o p h y t e s a p p e a r t o w i t h s t a n d wave a n d c u r r e n t a c t i v i t y f o r a p e r i o d l o n g e n o u g h a f t e r g e r m i n a t i o n t o become r o o t e d , b u t many may n o t w i t h s t a n d t h e s t r o n g e r wave a c t i v i t y i n w i n t e r . A l g a l m a t s were o b s e r v e d a r o u n d t h e l a r g e r hummocks, a n d t h e s e w o u l d i n d e e d c o n t r i b u t e t o t h e i r e l e v a t i o n . I n t h e w i n t e r , t h e mounds a r e e r o d e d , m a i n l y on t h e s e a w a r d s i d e . The f o r m a t i o n o f hummocks by T r i g l o c h i n was s t u d i e d i n t h e D o v e y E s t u a r y by Y a pp e_t a l . ( 1 9 1 7 ) , who f o u n d t h a t one o r more T r i g l o c h i n p l a n t s became e s t a b l i s h e d on t h e s i l t , a n d t h e i r r h i -zomes grew o u t a n d up, t r a p p i n g s e d i m e n t s a n d t h e r e b y i n c r e a s i n g t h e r e l i e f o f t h e hummock. Moody ( 1 9 7 8 ) commented on t h e c a p a -c i t y o f T r i g l o c h i n m a r i t i m u m on F r a s e r f o r e s h o r e m a r s h e s f o r e l e v a t i n g t h e m a r s h s u r f a c e . T h e e c o l o g i c a l / s e d i m e n t o l o g i c a l i n t e r a c t i o n o f p l a n t e s t a b -l i s h m e n t a n d t h e i n c r e a s e d c a p a c i t y t o t r a p s e d i m e n t s , w h i c h r a i s e s t h e e l e v a t i o n o f t h e a r e a , a r e w e l l d o c u m e n t e d i n t h e l i t e r a t u r e , a n d c o r r e s p o n d t o my o b s e r v a t i o n s i n B o u n d a r y B a y . The b i n d i n g a n d t r a p p i n g o f s e d i m e n t s by a l g a e h a s b e e n d o c u -m e n t e d by G i n s b u r g e t a l . ( 1 9 5 8 ) a n d G e b e l e i n ( 1 9 6 9 ) . G r a s s r o o t s a c t i n g a s b a f f l e s , p r o m o t i n g s e d i m e n t a c c u m u l a t i o n , a n d s t a b i l i z i n g t h e a r e a a r e d e s c r i b e d by B e r n a t o w i c z ( 1 9 5 2 ) , M o l i n i e r a n d P i c a r d ( 1 9 5 2 ) , G i n s b u r g ( 1 9 5 6 ) , R a n w e l l ( 1 9 6 4 ) , S c o f f i n ( 1 9 7 0 ) a n d P a t r i q u i n ( 1 9 7 5 ) . S e d i m e n t a t i o n r a t e s o f up t o 2 cm p e r y e a r a r e o b s e r v e d i n a r e a s c o l o n i z e d by C a r e x  l y n q b e i a t Woodward I s l a n d , F r a s e r R i v e r E s t u a r y ( E n v i r o c o n , 1 9 8 0 ) . D e v e l o p m e n t o f t h e S a l t M a r s h S a l t m a r s h d e v e l o p m e n t d o e s n o t a p p e a r t o be t h a t o f a t i m e - c o n t r o l l e d s u c c e s s i o n m i g r a t i n g o v e r t h e a r e a , b u t r a t h e r a p p e a r s r e l a t e d t o e l e v a t i o n r e l a t i v e t o s e a l e v e l . The d e v e l -opment i s s i m i l a r t o t h a t o f s a l t m a r s h e s i n o t h e r r e g i o n s o f t h e N o r t h e r n H e m i s p h e r e a n d f o l l o w s t h e s t a g e s i n s a l t m a r s h f o r m a t i o n d e s c r i b e d by Chapman ( 1 9 6 0 ) i n w h i c h he s t a t e s t h a t : 1. a l g a e a n d / o r e e l g r a s s e s c o l o n i z e t h e mud o r s a n d f l a t ; 2. a s t h e g r o u n d b e c o m e s h i g h e r , s u b a e r i a l p l a n t s s u c h a s S a l i c o r n i a s p p . o r P u c e i n e l l i a s p p . c o l o n i z e t h e a r e a ; 3. t h e e l e v a t i o n i n c r e a s e s a n d new s p e c i e s a p p e a r , i n c r e a s i n g t h e a c c r e t i o n r a t e a n d r e p l a c i n g t h e p r i m a r y c o l o n i s t s by s u c -c e s s i v e l y more c o m p l e x c o m m u n i t i e s . I n t h e p r e s e n t s t u d y , e v i d e n c e o f s a l t m a r s h v e g e t a t i o n i s f o u n d d e e p e r ( a n d e a r l i e r ) i n c o r e s 3 a n d 5; t h e s e a r e a s may r e p r e s e n t t o p o g r a p h i c l o w s ( p o s s i b l y f o r m e r c h a n n e l s ) w h i c h were p r e f e r e n t i a l l y c o l o n i z e d e a r l i e r t h a n a t o t h e r s i t e s . T h e d e -v e l o p m e n t o f t h e s a l t m a r s h , a s i n t e r p r e t e d f r o m p a l y n o l o g i c a l a n a l y s e s o f t h e c o r e s , i s s u m m a r i z e d i n F i g u r e 20; p o l l e n d i a -g r a m s o f t h e c o r e s may be f o u n d i n F i g u r e s 23 t h r o u g h 33. The s a l t m a r s h a t 6 4 t h S t r e e t i s i n t e r p r e t e d a s h a v i n g d e -v e l o p e d on m a r i n e s a n d s , c o m m e n c i n g a b o u t 3 4 5 ± 7 5 y r s B.P. ( T e l e d y n e , 1-11, 7 6 4 ) , a d a t e on o r g a n i c - r i c h s a n d s c o n -t a i n i n g a b u n d a n t S a l i c o r n i a p o l l e n a t 24 cm i n c o r e 6. T h e o r i g i n o f t h e s a n d i s u n c e r t a i n . T h e y c o u l d r e p r e s e n t d e l t a i c s a n d s d e p o s i t e d by t h e F r a s e r R i v e r , w i t h some m a r i n e i n f l u e n c e ; h o w e v e r , t h e i r s h a l l o w n e s s a n d s i t u a t i o n on t h e i n a c t i v e d e l t a f r o n t s u g g e s t t h a t t h e y may be s o l e l y d ue t o m a r i n e i n t e r t i d a l d e p o s i t i o n a n d d e r i v e d f r o m P o i n t R o b e r t s o r t h e F r a s e r R i v e r . T h e w a t e r s f r o m w h i c h t h e s e d i m e n t s w e r e d e p o s i t e d c o n t a i n e d p o l l e n o f t h e m a i n s p e c i e s o f t h e C o a s t f o r e s t , a s d e s c r i b e d by K r a j i n a ( 1 9 6 9 ) ; a s s o c i a t e d w i t h t h e s e , t h e p r e s e n c e o f f o r a m i n i -f e r a , d i n o f l a g e l l a t e c y s t s a n d f i n e b l a c k d e t r i t u s ( H e b d a , 1977) s u g g e s t s a m a r i n e e n v i r o n m e n t . Low a b u n d a n c e s o f p o l l e n i n t h e d e e p e r s a m p l e s were o b s e r v e d ; c h e n o p o d p o l l e n may r e p r e s e n t an e a r l i e r d e v e l o p m e n t o f a s a l t m a r s h b u t were more l i k e l y d e r i v e d f r o m e l s e w h e r e a n d r e d e p o s i t e d w i t h t h e s a n d s . A l g a l m a t s , w h i c h c o v e r t h e i n n e r t i d a l f l a t s s e a w a r d o f t h e s a l t m a r s h ( F i g u r e 1 5 ) , l o c a l l y h a v e e l e v a t e d a r e a s , c o n t r i -b u t i n g t o t h e i n i t i a l d e v e l o p m e n t o f t h e s a l t m a r s h ; h o w e v e r , S a l i c o r n i a a p p e a r s t o be t h e d o m i n a n t p i o n e e r h a l o p h y t e i n t h e S 20 H 0) .§ 40 c a) °. 60 H r— S] 80 H a 100 3 I 6 325+75 53066_ 6906 h— —^.643767| ^ * INSET 1 100 metres post 1950 x^£>s 310±75X x . » , post 1950 320±70 ^^V^Tgg* 345±75 2TT I St9520 685T ^ 9 8 ^ T l 8 9 9 10 200 LEGEND F i g u r e 20, Increase in pollen abundance, mainly Salicornia (pollen grains/cm 3 ) Decrease in arboreal pollen abundance. Base of peat. Z ° n e containing abundant Atriplex - former strandline "'""',/- - Algal debris zone - positions of former algal mats. v " x345t75 Radiocarbon dates. Summary of the development of the s a l t marsh at 6 4th S t r e e t . c o r e s , a l t h o u g h a s s o c i a t e d w i t h T r i g l o c h i n i n c o r e 7. S a l i c o r n i a c a n t o l e r a t e e n v i r o n m e n t s o f h i g h e r s a l i n i t i e s , b u t i s r e d u c e d t o a p h y l l o c l a d e f o r m w h i c h h a s m i n u t e l e a f a p p e n -d a g e s r e s i s t a n t t o t e a r i n g by wave a c t i o n , a n d h a s d e v e l o p e d s u c c u l e n c e , w h i c h makes i t r e s i s t a n t t o i n j u r y f r o m s a l t ( R a n w e l l ; 1 9 7 2 ) . C o l o n i z a t i o n a p p e a r s t o be v e r y r a p i d , p o l l e n a b u n d a n c e s u d d e n l y i n c r e a s e s w i t h t h e a p p e a r a n c e o f S a l i c o r n i a , s u g g e s t i n g t h a t t h e a r e a became s t a b l e o r e m e r g e n t . T h i s i s t y p i c a l o f many s a l t m a r s h e s ; t h e t h r e s h o l d l e v e l f o r s a l t m a r s h p l a n t g r o w t h d e v e l o p s q u i t e s u d d e n l y , a n d new c o l o n i z a t i o n o v e r a l a r g e s u r f a c e a r e a may o c c u r v e r y r a p i d l y ( R a n w e l l , 1 9 7 2 ) . West ( 1 9 5 6 ) , f o r e x a m p l e , f o u n d t h a t c o l o n i z a t i o n o f mud f l a t s by m a n g r o v e s i n C o l o m b i a i s q u i t e s u d d e n . As t h e s a l t m a r s h d e v e l o p s a n d b ecomes more e m e r g e n t , m a r i n e i n u n d a t i o n s d e c r e a s e i n f r e q u e n c y ; t h i s c a n be s e e n i n t h e c o r e s by a d e c r e a s e i n a b u n d a n c e o f c o a s t f o r e s t p o l l e n a n d a c o r r e s p o n d i n g i n c r e a s e i n h a l o p h y t e s a n d m e s o p h y t e s . S u c c e s s i v e c h a n g e s s e e n v e r t i c a l l y i n t h e c o r e s c a n be r e -l a t e d t o t h e l a t e r a l v e g e t a t i o n a l s e q u e n c e p r e s e n t on t h e modern t i d a l f l a t s . The a l g a l mat z o n e i s c o l o n i z e d by S a l i c o r n i a a n d T r i g l o c h i n , a s s e e n i n c o r e s 9 a n d 10. A l g a l d e b r i s i n c o r e 7 a t 25-30 cm, i n c o r e 8 a t 15-25 cm, a n d i n c o r e 9 r e p r e s e n t s p o s i t i o n s o f f o r m e r a l g a l m a t s . L a m i n a t e d s e d i m e n t s w e r e s e e n n e a r s t a t i o n 8 ( F i g u r e 2 1 ) , b u t t h e s e l a m i n a e w e r e d e s t r o y e d by v e g e t a t i o n r o o t s a n d c o u l d n o t be t r a c e d l a n d w a r d s b e n e a t h t h e s a l t m a r s h . S a l i c o r n i a a n d T r i g l o c h i n became e s t a b l i s h e d a s c a n be s e e n i n c o r e 8, a n d t h e f o r m a t i o n o f hummocks i s a p p a r e n t . A t c o r e 7, S p e r g u l a r i a a n d C u s c u t a , w h i c h a r e a l s o h a l o p h y t e s , F i g u r e 21. A l g a l l a m i n a t i o n s seen near S t a t i o n 5 3 . a r e p r e s e n t . The v e g e t a t i o n b ecomes more d i v e r s e u p w a r d s ; P l a n t a g o i s f o u n d i n c o r e 6. A z o n e o f A t r i p l e x , m a r k e d a t 0-5 cm i n c o r e 5, r e p r e s e n t s t h e s t r a n d l i n e , a n d h i g h e r c o n c e n t r a -t i o n s o f A t r i p l e x i n t h e c o r e s , s u c h a s a t 0-10 cm i n c o r e 4 a n d 10-20 cm i n c o r e 3, may r e p r e s e n t f o r m e r p o s i t i o n s o f t h e s t r a n -d l i n e . S e a w a r d o f s t a t i o n 5 i s t h e l o w e r , s u b m e r g e n t m a r s h , w h i c h i s f r e q u e n t l y f l o o d e d ; t h e a b u n d a n c e o f c o a s t f o r e s t p o l l e n p r e -s e n t i n c o r e s 6 t h r o u g h 10 r e f l e c t s t h e m a r i n e c h a r a c t e r o f t h i s a r e a . L a n d w a r d o f s t a t i o n 5 i s t h e u p p e r , e m e r g e n t m a r s h , u p o n w h i c h a p e a t i s p r e s e n t . S u c c e s s i v e c h a n g e s i n t h e p o l l e n a s s e -m b l a g e s i n t h e c o r e s r e p r e s e n t t h e e m e r g e n c e o f a d i v e r s e meso-p h y t i c v e g e t a t i o n . G r i n d e l i a i s a c o m p o s i t e a p p e a r i n g l o w e r i n t h e c o r e s , a n d i s f o u n d o u t t o s t a t i o n 6. A z o n e w i t h a b u n d a n t g r a s s e s t h e n d e v e l o p s , a n d more c o m p o s i t e s a r e f o u n d h i g h e r i n t h e c o r e s a s t h e v e g e t a t i o n b ecomes more e s t a b l i s h e d a n d v a r i e d . The most e m e r g e n t z o n e i s s e e n o n l y a t t h e i n n e r m a r g i n o f t h e m a r s h , i n t h e d y k e c o r e a n d c o r e 1, w h e r e A s t e r , A g o s e r i s , a n d R o s a c e a e ( p r o b a b l y M a i u s f u s c a ) a r e f o u n d . S a l i c o r n i a i s p r e -s e n t t h r o u g h o u t t h e c o r e s - i t c a n l i v e i n many e n v i r o n m e n t s , w h e r e a s m e s o p h y t e s a r e more h i g h l y s p e c i a l i z e d a n d r e q u i r e s p e -c i f i c g r o w t h c o n d i t i o n s . A w i d e s p r e a d d e c r e a s e i n t h e p r o p o r -t i o n s o f c o a s t f o r e s t s p e c i e s s e e n i n t h e d y k e c o r e a n d c o r e s 1, 2, 3, a n d 4 a t a b o u t 20 cm s u g g e s t s : 1) m a r s h e m e r g e n c e a n d m a r i n e f l o o d i n g s , a c c o m p a n i e d by c o a s t f o r e s t p o l l e n , b e c o m i n g l e s s f r e q u e n t ; 54. 2) c o a s t f o r e s t p o l l e n s o u r c e - a r e a s b e i n g removed; or 3) d r a i n a g e c h a n n e l s f l o w i n g i n t o the area b e i n g d i v e r t e d away from a source of c o a s t f o r e s t p o l l e n (G.E. Rouse, 1980, o r a l commun.) An i n c r e a s e i n the abundance of A l n u s near the top of most c o r e s can be a t t r i b u t e d t o h i s t o r i c a l l a n d c l e a r i n g ; A l n u s i s a p i o n e e r s p e c i e s on d i s t u r b e d s i t e s . D i s p e r s a l of p o l l e n by wind and water i s apparent i n the c o r e s ; s p e c i e s p r e s e n t i n low abun-dances i n the sands are thought t o have been i n t r o d u c e d . Rates of Development and A c c r e t i o n of the S a l t Marsh The s a l t marsh appears t o have dev e l o p e d r a p i d l y over a d i s t a n c e of 315 m from the dyke t o s t a t i o n 5. A w e l l d e v e l o p e d , woody peat i s found above the o r g a n i c sandy c l a y and f i n e sands; the base of the o r g a n i c r i c h sand, w i t h an a s s o c i a t e d i n c r e a s e i n p o l l e n abundance, i s taken as the commencement of s a l t marsh development, and has been dated as 320±70 y e a r s B.P. (GSC-3186) at a depth of 35 cm i n c o r e 5. There appears t o have been a subsequent h a l t i n the p r o g r a d a t i o n of the marsh, and a s m a l l marine t r a n s g r e s s i o n i s e n v i s a g e d , as e e l g r a s s and t i d a l d e b r i s o v e r l i e s a woody peat i n core 5. The seaward f r o n t of the marsh i s p r e s e n t l y d e v e l o p i n g over the t i d a l f l a t s , as seen by p a l y n o -l o g i c a l e v i d e n c e i n the c o r e s . The average r a t e of v e r t i c a l a c c r e t i o n i s 0.5 mm/yr a t s t a -t i o n 1, which i s slow compared t o 3 cm per year at s t a t i o n 5; t h i s i s due t o d e p o s i t i o n of o r g a n i c d e b r i s by the t i d e s at the l a t t e r s i t e . The peat a t s t a t i o n 1 may once have been t h i c k e r , w i t h i t s u p p e r p a r t b e i n g d e s t r o y e d by f i r e . M i n e r a l c h a r c o a l , a t t r i b u t e d t o f i r e , was s e e n a t 5 t o 10 cm i n t h e d y k e c o r e . A l g a l l a m i n a e , seen b e t w e e n s t a t i o n s 7 and 8 ( F i g u r e 2 1 ) , i n d i c a t e 1 cm o f s a n d b e i n g d e p o s i t e d a n n u a l l y f o r t h r e e y e a r s . -Much e r o s i o n and r e w o r k i n g o f t h e s e d i m e n t s o c c u r s on t h e t i d a l f l a t s , and t h i s v a l u e i s n o t r e p r e s e n t a t i v e o f t h e o v e r a l l s e d i -m e n t a t i o n r a t e a s i n t e r p r e t e d f r o m t h e r a d i o c a r b o n d a t e s . 5 6 . The P e a t a t 1 1 2 t h S t r e e t A p a r t l y b u r i e d p e a t was s t u d i e d on t h e f o r e s h o r e s o u t h o f 1 1 2 t h S t r e e t , S o u t h D e l t a , B.C. Where e x p o s e d , i t i s b e i n g a c -t i v e l y ' e r o d e d , b u t p a r t s h a v e b e e n c o v e r e d by s i l t s a n d c l a y s . E r o s i o n was o b s e r v e d t o be o c c u r r i n g i n t h e e a s t p a r t o f t h e Bay by K e l l e r h a l s a n d M u r r a y ( 1 9 6 9 ) , who f o u n d t h a t a c l i f f 60 cm h i g h f o r m e d t h e s e a w a r d e d g e o f t h e s a l t m a r s h a t Mud B a y . T h e m o dern d e v e l o p m e n t o f s a l t m a r s h v e g e t a t i o n o c c u r s i n a n a r r o w d i s c o n t i n u o u s b a n d i m m e d i a t e l y s e a w a r d o f t h e d y k e . K e l l e r h a l s a n d M u r r a y ( 1 9 6 9 ) d e s c r i b e d t h e b u r i e d p e a t a s t h e r e m n a n t o f a f o r m e r e x t e n s i v e s a l t m a r s h . Wood embedded i n t h e p e a t g a v e a r a d i o c a r b o n a g e o f 4 3 5 0 ± 1 0 0 y e a r s B.P. ( G X - 0 7 8 1 ) . T h e y s u g -g e s t e d t h a t t h e m a r s h d e v e l o p e d when t h e S o u t h Arm o f t h e F r a s e r R i v e r f l o w e d s o u t h w a r d i n t o B o u n d a r y B a y ; s u b s i d e n c e l a t e r a l -l o w e d t h e s e a t o t r a n s g r e s s o v e r a n d e r o d e t h e e a r l i e r m a r s h d e p o s i t . The p r e s e n t s t u d y s u g g e s t s a more c o m p l e x h i s t o r y . T h r e e c o r e s , 11, 12, a n d 13, ( F i g u r e 5) were c o l l e c t e d a n d , f r o m t h e p o l l e n a n a l y s e s ( F i g u r e s 22, 34, 35 a n d 3 6 ) , a p a l e o e n -v i r o n m e n t a l r e c o n s t r u c t i o n i s s u g g e s t e d i n w h i c h a f r e s h w a t e r p o n d o r bog e n v i r o n m e n t , p e r h a p s a s s o c i a t e d w i t h t h e " G r e a t C h a n n e l " ( K e l l e r h a l s a n d M u r r a y , 1 9 6 9 ) , was s u c c e s s i v e l y i n u n -d a t e d by m a r i n e w a t e r s a n d c o n v e r t e d t o a s a l t m a r s h . T h e s u c -c e s s i o n was: 1. e s t a b l i s h m e n t o f f e r n s , s u g g e s t i n g a f r e s h w a t e r e n v i r o n -ment; 2. T y p h a , N u p h a r , a n d s e d g e s grew i n a n d a r o u n d t h e f r e s h w a -t e r a r e a ; Figure 22. Composite section of zones found i n the cores obtained near 112th Street. CORE 11 58. 3. g r a d u a l e n c r o a c h m e n t o f s e a w a t e r , t h e s e d g e s b e i n g t h e m o s t t o l e r a n t t o t h e c h a n g e i n e n v i r o n m e n t ; a n d 4. t h e d e v e l o p m e n t o f s a l t m a r s h a s i n d i c a t e d by S a l i c o r n i a , A t r i p l e x , a n d T r i g l o c h i n . L a t e r , c o m p o s i t e s a p p e a r e d a s t h e m a r s h became more e m e r g e n t . G r a s s e s a r e a b u n d a n t t h r o u g h o u t t h e c o r e s ; S a l i c o r n i a a n d A t r i p l e x , p r e s e n t l o w e r i n t h e c o r e s , may h a v e b e e n i n t r o d u c e d o r may r e p r e s e n t v e g e t a t i o n g r o w i n g on t h e d i t c h t u r f l i n e a r o u n d t h e f r e s h w a t e r bog (Chapman, 1 9 7 6 ) . C o a s t f o r e s t s p e c i e s ( K r a j i n a , 1969) a r e a b u n d a n t i n t h e f r e s h w a t e r e n v i r o n m e n t ; e i t h e r a f o r e s t grew n e a r b y o r r i v e r s t r a n s p o r t e d t h e s e p o l l e n i n t o t h e a r e a . The f r e q u e n c y o f t h e s e p o l l e n d e c r e a s e s w i t h t h e a d v e n t o f t h e s a l t m a r s h , a s o b s e r v e d a t 6 4 t h S t r e e t , b u t i n -c r e a s e s i n c o r e 12 a t a d e p t h o f 16 cm, w h e r e m a r i n e w a t e r s d e -p o s i t e d s i l t s l a d e n w i t h s u c h p o l l e n a b o v e t h e p e a t . C o r e 11 shows t h e m o s t e m e r g e n t s u c c e s s i o n , w h e r e a s c o r e 13 shows t h e commencement o f s a l t m a r s h d e v e l o p m e n t ; t h i s c a n be e x p l a i n e d by g r e a t e r e r o s i o n of. t h e p e a t s f u r t h e r away f r o m l a n d by a t r a n s -g r e s s i n g s e a . T h e s e q u e n c e s e e n i n t h e p e a t s a t 1 1 2 t h S t r e e t i s t h e r e -v e r s e t o t h a t o b s e r v e d i n New E n g l a n d s a l t m a r s h e s by Chapman ( 1 9 6 0 ) . He o b s e r v e d d e v e l o p m e n t f r o m m a r i n e mud t o e e l g r a s s , t o g r a s s e s , t o s e d g e s , a n d f i n a l l y t o a T y p h a r e e d swamp a s t h e w a t e r b e c o m e s i n c r e a s i n g l y f r e s h . T h i s c y c l e i s a s s o c i a t e d w i t h e m e r g e n c e ; t h e s e q u e n c e s e e n i n t h e p e a t s a t 1 1 2 t h S t r e e t s u g -g e s t s s u b m e r g e n c e o f a f r e s h w a t e r e n v i r o n m e n t a n d s u b s e q u e n t e m e r g e n c e o f t h e s a l t m a r s h . The s e q u e n c e o f e v e n t s h e r e c o r r e -s p o n d s t o t h e t h a t d e s c r i b e d by K e l l e r h a l s a n d M u r r a y ( 1 9 6 9 ) . 59. They suggested that a freshwater environment p r e v a i l e d where the South Arm of the Fraser River entered Boundary Bay; t h i s en-vironment was l a t e r covered with s a l t water, causing the vegeta-t i o n to change and halophytes to i n c r e a s e in abundance. 6 0 . CHAPTER 4: D I S C U S S I O N AND CONCLUSIONS The s a l t m a r s h a t 6 4 t h S t r e e t a p p e a r s t o be a t y p i c a l m a r i -t i m e s a l t m a r s h . A d i s t i n c t i v e z o n a t i o n o f v e g e t a t i o n r e l a t e d t o e l e v a t i o n was o b s e r v e d , w i t h a v a r i e d m e s o p h y t i c f l o r a n e a r t h e d y k e . The v e g e t a t i o n b e c o m e s l e s s d i v e r s e s e a w a r d a n d i n -c r e a s i n g l y d o m i n a t e d by h a l o p h y t e s u n t i l S a l i c o r n i a a n d T r i g l o c h i n o c c u r a l o n e . The d e v e l o p m e n t o f t h e s a l t m a r s h , i n t e r p r e t e d f r o m p a l y n o -l o g i c a l a n a l y s e s o f c o r e s o b t a i n e d i n a t r a n s e c t a c r o s s t h e • s t u d y a r e a ( F i g u r e 2 0 ) , r e f l e c t s t h e s e q u e n c e o b s e r v e d h o r i z o n -t a l l y a t p r e s e n t ( F i g u r e 4 ) . S a l i c o r n i a a n d o c c a s i o n a l T r i g l o c h i n a r e t h e p i o n e e r h a l o p h y t e s c o l o n i z i n g t h e s e d i m e n t s . A l g a l mat d e v e l o p m e n t may i n i t i a l l y h a v e c o n t r i b u t e d t o an i n -c r e a s e i n e l e v a t i o n . As e l e v a t i o n i s f u r t h e r i n c r e a s e d , a c o r -r e s p o n d i n g i n c r e a s e i n t h e a b u n d a n c e a n d d i v e r s i t y o f p o l l e n o c c u r s . A s s o c i a t e d w i t h t h i s , a m a r k e d r e d u c t i o n i n t h e amount o f a r b o r e a l p o l l e n , t r a n s p o r t e d by t h e s e a w a t e r , s i g n i f i e s s u b -m e r g e n c e s b e c o m i n g l e s s f r e q u e n t a n d t h e m a r s h e m e r g i n g . A d i s -t i n c t i v e z o n e o f A t r i p l e x r e p r e s e n t s f o r m e r p o s i t i o n s o f t h e s t r a n d l i n e . F u r t h e r e m e r g e n c e o c c u r r e d a n d c o n t i n u e d u n t i l t h e m a r s h was s u f f i c i e n t l y e l e v a t e d f o r m e s o p h y t e s t o d o m i n a t e t h e v e g e t a t i o n ; p e a t a c c u m u l a t e d a n d , i n t h e most e m e r g e n t z o n e s , a v a r i e d , d i v e r s e f l o r a p e r s i s t e d . E l e v a t i o n i s t h e d o m i n a n t f a c t o r i n t h e d e v e l o p m e n t o f t h e m a r s h ; a s t h e m a r s h d e v e l o p s , a more v a r i e d v e g e t a t i o n e n h a n c e s t h e i n c r e a s e i n e l e v a t i o n . R a d i o c a r b o n d a t e s on o r g a n i c - r i c h s a n d s c o n t a i n i n g a b u n d a n t S a l i c o r n i a s u g g e s t t h a t t h e s a l t m a r s h commenced d e v e l o p m e n t .61. a b o u t 3 4 5 ± 7 5 y r s B.P. ( T e l e d y n e , 1-11, 7 6 4 ) . D e v e l o p m e n t i s e n v i s a g e d t o h a v e o c c u r r e d i n two s t a g e s ; i n t h e a r e a b e t w e e n t h e d y k e a n d S t a t i o n 5, t h e a r e a became e m e r g e n t , a n d a p e a t d e v e l o p e d b e n e a t h an i n c r e a s i n g l y d i v e r s e f l o r a . A s u b s e q u e n t p a u s e i n d e v e l o p m e n t o r a t r a n s g r e s s i o n o c c u r r e d , d u r i n g w h i c h e e l g r a s s was d e p o s i t e d a b o v e t h e p e a t a t s t a t i o n 5; t h i s now f o r m s t h e s t r a n d l i n e . F o l l o w i n g t h i s , d e v e l o p m e n t o f t h e m a r s h c o n t i n u e d t o t h e p r e s e n t . The p e a t f r o m 1 1 2 t h S t r e e t shows a s u c c e s s i o n f r o m a f r e s h -w a t e r t o a s a l t m a r s h e n v i r o n m e n t ( F i g u r e 2 2 ) . F e r n s grew a n d , l a t e r , T y p h a , N u p h a r , a n d s e d g e s d e v e l o p e d . T h e s e d e c r e a s e i n a b u n d a n c e a s t h e a r e a i s s u c c e s s i v e l y i n u n d a t e d by m a r i n e w a t e r , t h e s e d g e s b e i n g t h e s p e c i e s most t o l e r a n t o f t h e c h a n g i n g e n -v i r o n m e n t . C h e n o p o d p o l l e n b e c o m e s a b u n d a n t a s t h e s a l t m a r s h d e v e l o p s , a n d a t r e n d t o w a r d s e m e r g e n c e o c c u r s a s t h e v e g e t a t i o n b e c o m e s i n c r e a s i n g l y more d i v e r s e . T h e most c o m p l e t e s e q u e n c e was o b s e r v e d i n c o r e 1 1 . R a d i o c a r b o n d a t e s were o b t a i n e d f r o m t h e b a s e o f t h e p e a t ; c o r e 12 a t 41 t o 44 cm was d a t e d a s 3 1 3 0 ± 5 0 y r s B.P. ( G S O 3 2 0 2 ) a n d c o r e 13 a t 12 t o 14 cm was d a t e d a s 3 9 1 0 ± 6 0 y r s B.P. (GSC-3 1 8 3 ) . F r o m t h e same a r e a , K e l l e r h a l s a n d M u r r a y ( 1 9 6 9 ) d e s -c r i b e a p e a t d a t e d a t 4 3 5 0 ± 1 0 0 y e a r s B.P.. (GX-0781) , a n d C l a g u e ( w r i t t e n commun., 1980) o b t a i n e d a d a t e o f 3 7 8 0 ± 9 0 y r s B.P. ( G S C - 3 0 8 7 ) a t a d e p t h o f 1 m i n a p e a t i m m e d i a t e l y s e a w a r d o f t h e d y k e . T h e s e p e a t s may r e p r e s e n t one s e q u e n c e f r o m a f r e s h -w a t e r t o a s a l t m a r s h e n v i r o n m e n t , o r t h e y c o u l d h a v e d e v e l o p e d i n f o r m e r c h a n n e l s , b e i n g s u b j e c t e d t o p e r i o d i c e r o s i o n a n d r e -62. peated s a l t marsh development. P o l l e n s and spores, being m o r p h o l o g i c a l l y d i v e r s e and r e s i -stant to degradation, are v a l u a b l e f o r the i n t e r p r e t a t i o n of paleoenvironments. The p o l l e n of the s a l t marsh v e g e t a t i o n was observed to occur mainly in the source areas (Figure 17), and was not s u b j e c t to widespread d i s p e r s a l by wind and water as were the coast f o r e s t p o l l e n . T h i s was e s p e c i a l l y n o t i c e a b l e i n the case of S a l i c o r n i a p o l l e n , which appear to be most wides-pread in a s a l t marsh environment. This study has shown that p a l y n o l o g i c analyses can be used to r e c o n s t r u c t stages in the development of s a l t marshes at Boundary Bay; s i m i l a r s t u d i e s may be e q u a l l y s u c c e s s f u l i n other areas. Palynoassemblage sequences can be used to i d e n t i f y the main t r a n s g r e s s i v e and r e g r e s s i v e phases of sedimentation i n c o a s t a l environments, as seen here in the r e c o g n i t i o n of a f r e -shwater to marine t r a n s i t i o n in the peat sequence at 112th S t r e e t . 6 3 . REFERENCES C I T E D A r m s t r o n g , J . E . , 1 9 5 6 a , M a n k a t o D r i f t i n t h e L o w e r F r a s e r V a l l e y o f B r i t i s h C o l u m b i a , C a n a d a : G e o l o g i c a l S o c . A m e r i c a B u l l . , 67, 1 6 6 6 - 1 6 6 7 . A r m s t r o n g , J . 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Yamanaka, K., 1 9 7 5 , P r i m a r y p r o d u c t i v i t y o f t h e F r a s e r D e l t a f o r e s h o r e : y i e l d e s t i m a t e s o f e m e r g e n t v e g e t a t i o n : T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , D e p a r t m e n t o f P l a n t S c i e n c e , M.Sc. t h e s i s , 133 p . Ya p p , R.H., D. J o h n s , a n d O.T. J o n e s , 1917, The s a l t m a r s h e s o f t h e D o v e y E s t u a r y : J o u r . E c o l o g y , 5, 6 5 - 1 0 3 . Y a s s o , W.E., 1 9 6 5 , P l a n g e o m e t r y o f h e a d l a n d - b a y b e a c h e s : J o u r . G e o l o g y , 73, 7 0 2 - 7 1 3 . APPENDIX I P o l l e n Diagrams and D e s c r i p t i o n s of the Cores Dyke C o r e ( 0 - 6 0 cm) ( F i g u r e 2 3)' The m o s t l a n d w a r d c o r e was o b t a i n e d 5.0 m s o u t h - s o u t h e a s t o f t h e s o u t h s i d e o f t h e d y k e a t 6 4 t h S t r e e t ( F i g u r e 4 ) . The s a n d y l o w e r p a r t o f t h e c o r e ( 3 0 - 6 0 cm) h a s a low p a l y n o m o r p h a b u n d a n c e . D i n o f l a g e l l a t e c y s t s o c c u r a t b o t h 35-40 cm a n d 5 5 -60 cm. Some C h e n o p o d , G r a m i n e a e , a n d T r i g l o c h i n p o l l e n were f o u n d . A r b o r e a l p o l l e n i s a b u n d a n t i n t h e l o w e r p a r t o f t h e c o r e , b u t shows a m a r k e d d e c l i n e u p w a r d s a s t h e s a l t m a r s h s t a r t s t o d e v e l o p a t a b o u t 30 cm, a c c o m p a n i e d by a s h a r p i n -c r e a s e i n t h e a b u n d a n c e o f S a l i c o r n i a . The p o l l e n a b u n d a n c e i n c r e a s e s f r o m 2673 t o 1 10,489 cm" 3 a s c o l o n i z a t i o n a n d emer-g e n c e o c c u r . P e a t p e r s i s t s f r o m 20 cm u p w a r d s . A b o v e 15 cm, g r a s s e s , Gr i n d e l i a , A s t e r , A g o s e r i s, a n d R o s a c e a e a r e i n c r e a s i n g l y more a b u n d a n t . T h e r e i s a m a r k e d u p w a r d d e c r e a s e i n t h e p r o p o r t i o n o f c o a s t f o r e s t p o l l e n ( K r a j i n a , 1969) a t a b o u t 20 cm, t o g e t h e r w i t h a c o r r e s p o n d i n g i n c r e a s e i n f u n g a l s p o r e s . C O R E DEPTH, centimetres cn o 01 o o w o ro O 33 03 o o m CD CO <x> CO 5' CD Q. Tl m m z a CQ o' —^ o' J3 J3 o o CD TTT O TJ > Z CD m o O o > T l c -^  CD ro co CO 4^ CD rjo o c CL UJ r CD O C O R E DEPTH, centimetres o .71. C o r e 1 ( 0 - 8 0 cm) ( F i g u r e 24) I n t h i s c o r e , s e d i m e n t s c o n t a i n i n g c o a s t f o r e s t p o l l e n a n d some d i n o f l a g e l l a t e c y s t s a r e f o u n d up t o a d e p t h o f 35 cm. A t 30 cm, an a b r u p t i n c r e a s e i n S a l i c o r n i a o c c u r s a n d t h e s a n d s become s l i g h t l y c l a y e y a n d c o n t a i n o r g a n i c m a t t e r . T r i g l o c h i n a b u n d a n c e s i n c r e a s e a l s o . A r b o r e a l p o l l e n a b u n d a n c e d e c r e a s e s u p w a r d s a n d p e a t f o r m a t i o n b e g i n s a t a d e p t h o f 14 cm. G r a s s e s o c c u r a n d t h e number o f c o m p o s i t e s i n c r e a s e a s t h e v e g e t a t i o n a l s u c c e s s i o n p r o c e e d s . The h i g h e r f r e q u e n c y o f g r a s s e s l o w e r i n t h e c o r e may be due t o t h e i r b e i n g t r a n s p o r t e d by w a t e r . C o r e 2 ( 0 - 9 5 cm) ( F i g u r e 25) I n c o r e 2, s a n d s c o n t a i n i n g a low a b u n d a n c e o f p a l y n o m o r p h s o c c u r up t o 35 t o 40 cm. H i g h e r f r e q u e n c i e s o f g r a s s e s , S a l i c o r n i a , T r i g l o c h i n , a n d A t r i p l e x b e t w e e n 35-55 cm a n d 80-95 cm p r o b a b l y r e p r e s e n t i n t r o d u c e d p o l l e n g r a i n s o r s h o r t - l i v e d , l o c a l p a t c h e s o f s a l t m a r s h v e g e t a t i o n . A t 35 cm S a l i c o r n i a a n d T r i g l o c h i n i n c r e a s e . An i n c r e a s e i n t h e a b u n d a n c e o f g r a s s e s a t 30 cm a n d t h e s u b s e q u e n t i n c r e a s e s shown by G r i n d e l i a a n d A s t e r o c c u r h i g h e r i n t h e c o r e . P e a t h a s d e v e l o p e d t o a d e p t h o f 13 cm a n d c o a s t f o r e s t p o l l e n s d e c r e a s e i n a b u n d a n c e h i g h e r i n t h e c o r e . A l a c k o f R o s a c e a e h e r e s u g g e s t s t h a t t h i s a r e a was n o t e m e r g e n t e n o u g h f o r t h e g r o w t h o f M a l u s f u s c a . 7 2 . Figure 24 TRANSECT LOCATION: 64th St., Boundary Bay 25% 74. Core 3 (0-60 cm) (Figure 26) Sediments c o n t a i n i n g coast f o r e s t p o l l e n occur up to 40 cm in core 3, with higher c o n c e n t r a t i o n s of S a l i c o r n i a , A t r i p l e x , and grasses probably being i n t r o d u c e d i n t o the sands. At 40 cm, a r b o r e a l p o l l e n decreases and S a l i c o r n i a i n c r e a s e s d r a m a t i c a l l y . Successive i n c r e a s e s in T r i g l o c h i n , g r asses, and Atr i p l e x occur. Peat developed from 14 cm upwards, and A s t e r , G r i n d e l i a , and A g o s e r i s are more abundant at the top of the core. Core 4 (0-60 cm) (Figure 27) In core 4, much a l g a l d e b r i s was found i n the sands up to a depth of 25 cm, where the p o l l e n abundance i n c r e a s e s from 357 to 6944 cm" 3, with S a l i c o r n i a becoming abundant. S a l i c o r n i a , A t r i p l e x , and grasses are present i n low abundances deeper in the c o r e . Grasses, Atr i p l e x , T r i g l o c h i n , and Cuscuta (as a p a r a s i t e on S a l i c o r n i a ) are present higher up, with Gr i n d e l i a more abundant at the top. .Coast f o r e s t p o l l e n decreases drama-t i c a l l y at a depth of 15 cm. Figure 26 TRANSECT LOCATION: 64th St., Boundary Bay CORE 3 76. Figure 27 TRANSECT LOCATION: 64th St., Boundary Bay E O C o r e 5 ( 0 - 4 5 cm) ( F i g u r e 28) T h e s a l t m a r s h a p p e a r s t o h a v e commenced d e v e l o p m e n t d e e p e r i n c o r e 5 t h a n i n any o f t h e o t h e r c o r e s . B e t w e e n 40 a n d 45 cm, c o a s t f o r e s t p o l l e n s a r e a b u n d a n t . A t 35-40 cm S a l i c o r n i a a n d g r a s s e s i n c r e a s e , a n d a p e a t y h o r i z o n o c c u r s . A s u b s e q u e n t d e -c r e a s e i n g r a s s a b u n d a n c e a t 20-30 cm may s i g n i f y t h a t t h e e n -v i r o n m e n t , p r e v i o u s l y more e m e r g e n t , became s u b m e r g e n t o r u n s u i -t a b l e f o r t h e c o n t i n u e d g r o w t h o f s u c h g r a s s e s , l e a v i n g S a l i c o r n i a a s t h e d o m i n a n t p l a n t . T h i s may r e p r e s e n t c o l o n i z a -t i o n o f a l o c a l h i g h on t h e f o r e s h o r e . D i n o f l a g e l l a t e c y s t s w ere f o u n d a t 25-35 cm a n d 15-20 cm. S a l i c o r n i a a n d T r i g l o c h i n c o m p r i s e t h e p i o n e e r v e g e t a t i o n , w i t h a s s o c i a t e d g r a s s e s a n d A t r i p l e x , u n t i l A t r i p l e x g r e a t l y i n c r e a s e s i n a b u n d a n c e a t 0-5 cm a n d t h e o t h e r s d e c l i n e . T h e i n c r e a s e i n A t r i p l e x r e p r e s e n t s t h e c o l o n i z a t i o n o f t h e s t r a n d l i n e , w i t h a 4 cm . t h i c k e e l g r a s s mat o v e r l y i n g t h e p e a t . G r i n d e l i a a n d A s t e r a l s o o c c u r h i g h e r i n t h e c o r e . A r b o r e a l p o l l e n d e c r e a s e s u p w a r d s , b u t o c c u r s i n h i g h e r f r e q u e n c i e s a t t h e t o p t h a n i n c o r e 4; t h i s s u g g e s t s p o l l e n d e p o s i t e d by h i g h e r w i n t e r t i d e s a n d s t o r m s . CORE DEPTH, centimetres 79. C o r e 6 (0-30 cm) ( F i g u r e 29) C o r e 6 i s i n t h e l o w e r , s u b m e r g e n t m a r s h . S a l t m a r s h v e g e -t a t i o n i s p r e s e n t t h r o u g h o u t t h e e n t i r e s h a l l o w c o r e , b u t t h e p r e s e n c e o f f o r a m i n i f e r a i n d i c a t e s f r e q u e n t s u b m e r g e n c e by m a r i n e w a t e r s . S a l i c o r n i a i s v e r y a b u n d a n t i n t h e c o r e , d e c r e a -s i n g i n f r e q u e n c y a t 0-5 cm a n d a p p a r e n t l y r e p l a c e d by T r i g l o c h i n , w h i c h shows a c o r r e s p o n d i n g i n c r e a s e i n f r e q u e n c y . G r a s s e s a r e p r e s e n t t h r o u g h o u t i n s i g n i f i c a n t n u m b e r s , w i t h s m a l l a m o u n t s o f A t r i p l e x a n d P l a n t a q o . A l a c k o f c o m p o s i t e s , w i t h t h e e x c e p t i o n o f some G r i n d e l i a , i s n o t a b l e . The f r e q u e n c y o f b l a d d e r e d c o n i f e r s d e c r e a s e s a t 0-5 cm, a s s o c i a t e d w i t h t h e f o r m a t i o n o f a p e a t a n d t h e commencement o f e m e r g e n c e o f t h e s a l t m a r s h . C o r e 7 (0-30 cm) ( F i g u r e 30) S a l t m a r s h v e g e t a t i o n i s p r e s e n t t h r o u g h o u t t h e c o r e b u t shows an i n c r e a s e d a b u n d a n c e o f T r i g l o c h i n a t 20-25 cm. S a l i c o r n i a i n c r e a s e s a t 20 cm, w h e r e a s T r i g l o c h i n d e c r e a s e s ; t h i s may i n d i c a t e t h a t t h e two s p e c i e s c o m p e t e i n t h e c o l o n i z a -t i o n o f s u i t a b l e a r e a s . S a l i c o r n i a a n d T r i g l o c h i n , w i t h g r a s s e s , a n d some A t r i p l e x a n d P l a n t a g o h i g h e r i n t h e c o r e , make up t h e m a i n v e g e t a t i o n h e r e . A g a i n , a l a c k o f c o m p o s i t e s was o b s e r v e d , a n d f o r a m i n i f e r a a n d some a l g a l d e b r i s d i s t r i b u t e d t h r o u g h o u t t h e c o r e s u g g e s t f r e q u e n t m a r i n e i n u n d a t i o n s . C o a s t f o r e s t p o l l e n s d e c r e a s e a t 0-5 cm. 81. C o r e 8 ( 0 - 3 0 cm) ( F i g u r e 31) C o r e 8, t a k e n f r o m a hummock a t t h e s e a w a r d e d g e o f t h e s a l t m a r s h , d o e s n o t show t h e s i g n i f i c a n t i n c r e a s e i n S a l i c o r n i a o b s e r v e d i n o t h e r c o r e s . S a l i c o r n i a , T r i g l o c h i n , g r a s s e s , a n d A t r i p l e x a r e p r e s e n t t h r o u g h o u t t h e c o r e , w i t h some P l a n t a g o a t t h e t o p . T h e a r e a i s f r e q u e n t l y f l o o d e d , a n d p o l l e n o f c o a s t f o r e s t s p e c i e s a r e a b u n d a n t t h r o u g h o u t . C o n c e n t r a t i o n s o f a l g a l d e b r i s a t 15-25 cm may r e p r e s e n t p o s i t i o n s o f f o r m a l a l g a l m a t s , w h i l s t a c o r r e s p o n d i n g low i n T r i g l o c h i n may s u g g e s t l o c a l e r o -s i o n a n d r e t r e a t o f t h e s t r a n d l i n e . C o r e 9 ( 0 - 1 5 cm) ( F i g u r e 32) T h i s c o r e , t a k e n i n t h e a l g a l mat z o n e , c o n t a i n s a l g a l d e b r i s a n d shows no d e v e l o p m e n t o f s a l t m a r s h v e g e t a t i o n . S m a l l a m o u n t s o f S a l i c o r n i a , T r i g l o c h i n , A t r i p l e x , a n d g r a s s e s a r e p r e s e n t t h r o u g h o u t , w i t h o c c a s i o n a l P l a n t a g o a n d A s t e r ; t h e s e p r o b a b l y were d e r i v e d f r o m t h e i n n e r z o n e o f t h e s a l t m a r s h . C o a s t f o r e s t p o l l e n was i n t r o d u c e d by s e a w a t e r , a n d a s h a r p i n -c r e a s e i n A l n u s o c c u r s a t 5 cm. C o r e 10 ( 0 - 1 0 cm) ( F i g u r e 33) C o r e 10, t a k e n f r o m t h e most s e a w a r d s m a l l T r i g l o c h i n hum-mock, c o n t a i n s T r i g l o c h i n , S a l i c o r n i a , A t r i p l e x , g r a s s e s , a n d a r b o r e a l p o l l e n , a l l o f w h i c h , w i t h t h e e x c e p t i o n o f some T r i g l o c h i n , h a v e b e e n d e r i v e d f r o m o u t s i d e t h e z o n e w h e r e t h e -c o r e was t a k e n . A l n u s shows a h i g h f r e q u e n c y i n c o r e 10, a s i t d o e s i n c o r e 9. 83. C o r e 11 ( 0 - 5 8 cm) ( F i g u r e 34) L a e v i g a t o f e r n s d o m i n a t e t h e o r g a n i c - r i c h c l a y s a t 50-58 cm. T y p h a a n d s e d g e s i n c r e a s e i n a b u n d a n c e a t 45-50 cm a n d r e m a i n t h e d o m i n a n t v e g e t a t i o n up t o 35-40 cm. Some N u p h a r a n d P t e r i d i u m a r e a s s o c i a t e d w i t h t h e s e p l a n t s a l s o . G r a s s e s o c c u r a n d some c o a s t f o r e s t s p e c i e s a r e p r e s e n t , p e r h a p s i n t r o d u c e d by m a r i n e w a t e r s o r b l o w n i n f r o m t h e n e a r b y f o r e s t e d a r e a o f t h e B l a i n e U p l a n d s ( F i g u r e 1 ) . H i g h e r f r e q u e n c i e s o f S a l i c o r n i a a n d A t r i p l e x o c c u r s p o r a d i c a l l y . T y p h a a n d s e d g e s d e c r e a s e i n a b u n -d a n c e a t a b o u t 40 cm, t h e b a s e o f t h e p e a t , s u g g e s t i n g t h e b e -g i n n i n g o f s u b m e r g e n c e o f t h e a r e a , w i t h t h e f r e s h w a t e r v e g e t a -t i o n g r a d u a l l y d y i n g o u t . T y p h a c a n w i t h s t a n d s a l i n i t i e s t o 1.13% i n t h e s o i l w a t e r ( P e n f o l d a n d H a t h a w a y , 1 9 3 8 ) , a n d some s e d g e s a n d r u s h e s c a n l i v e i n b r a c k i s h e n v i r o n m e n t s , a s s e e n by t h e p r e s e n t o c c u r r e n c e o f J u n c u s i n t h e s a l t m a r s h a t 6 4 t h S t r e e t . S a l i c o r n i a a n d T r i g l o c h i n i n c r e a s e a t a b o u t 40 cm. A t r i p l e x a n d g r a s s e s a r e p r e s e n t h i g h e r i n t h e c o r e a n d s m a l l n umbers o f A s t e r a n d Gr i n d e l i a r e p r e s e n t a d i v e r s i f y i n g v e g e t a -t i o n . C o a s t f o r e s t p o l l e n d e c r e a s e s a t t h e t o p o f t h e c o r e . 85. C o r e 12 ( 0 - 4 6 cm) ( F i g u r e 35) M o n o l e t e f e r n s d o m i n a t e t h e b a s a l p e a t y c l a y a t 41-46 cm i n c o r e 12, - o b t a i n e d 200 m s e a w a r d o f t h e d y k e , d e c r e a s i n g u p w a r d s i n t h e p e a t a t 41 cm, where T y p h a a n d s e d g e s become n u m e r o u s . A s t e r , S a l i c o r n i a , a n d A t r i p l e x a r e p r e s e n t i n low f r e q u e n c i e s i n t h e p e a t y c l a y . C o a s t f o r e s t p o l l e n i s a b u n d a n t up t o 36 cm, a n d g r a s s e s a r e n u m e r o u s . S a l i c o r n i a , T r i g l o c h i n , a n d A t r i p l e x i n c r e a s e a t 36 cm; T y p h a c e a s e s a t t h i s d e p t h a n d s e d g e s become a b u n d a n t . U p w a r d s i n t h e c o r e , i n c r e a s i n g a m o u n t s o f h a l o p h y t e s a n d g r a s s e s o c c u r ; s t i l l h i g h e r , G r i n d e l i a a n d A s t e r a r e p r e -s e n t . S a l t m a r s h p o l l e n c e a s e a t a d e p t h o f 16 cm. The o v e r -l y i n g c l a y s a n d s i l t s c o n t a i n b l a c k d e t r i t u s , F o r a m i n i f e r a , c o a s t f o r e s t p o l l e n , a n d some i n t r o d u c e d m e s o p h y t e a n d h a l o p h y t e p o l l e n . C o r e 13 (0-18 cm) ( F i g u r e 36) C o r e 13, o b t a i n e d 300 m s e a w a r d o f t h e d y k e a n d i m m e d i a t e l y w e s t o f t h e " G r e a t C h a n n e l " , was f o u n d t o c o n t a i n f e r n s a n d T y p h a i n t h e l o w e r o r g a n i c c l a y s , a s s o c i a t e d w i t h s m a l l a m o u n t s o f N u p h a r , s e d g e s , a n d c o a s t f o r e s t p o l l e n . A t 12 cm d e p t h ( t h e b a s e o f t h e p e a t ) , T y p h a , f e r n s , a n d c o a s t f o r e s t v e g e t a t i o n s h a r p l y d e c l i n e , w h i l s t s e d g e s , P t e r i d i u m , a n d g r a s s e s i n c r e a s e ; t h i s may r e p r e s e n t t h e b e g i n n i n g o f m a r i n e i n u n d a t i o n s o f t h e a r e a . S a l i c o r n i a , T r i g l o c h i n , a n d A t r i p l e x i n c r e a s e i n a b u n -d a n c e a t a b o u t 6 cm. H e r e , a s i n c o r e 12, t h e u p p e r e m e r g e n t s a l t m a r s h p e a t i s t r u n c a t e d ; i t may n o t h a v e d e v e l o p e d , b u t more l i k e l y i t h a s b e e n e r o d e d away. APPENDIX II P o l l e n Assemblage Data for the S t a t i o n s on the S a l t Marsh at 64th S t r e e t 88. P o l l e n assemblage data f o r S t a t i o n 1. / May June J u l y Aug. Sept. Oct. Nov. Pinus 11 15 4 1 4 Abies 1 Piaea Tsuga 7 7 1 1 2 Pseudotsuga 4 2 3 2 Cupressaceae 6 A Inus 3 7 13 3 1 1 6 Betula 1 Corylus 5 My via a Rosaceae 4 16 6 8 2 1 Sidaloea 2 61 20 1 Soliddgo-Achillea 21 32 6 Agoseris 1 611 679 163 3 17 Aster 19 90 36 137 47 Grindelia 17 5 1 3 Elymus 3 126 n o 12. 8 5 2 Other g r a s s e s 906 1886 41 329 12 ' 230 Rumex 1 5 11 2 Angelica 87 102 1 Salicornia 4 22 22 1 Atriplex 1 8 66 58 18 Vicid Plantago 2 10 5 2 1 Juncus 62 2 Cuscuta Spergularia Triglochin 35 100 4 Typha 1 1 Nuphar Monolete f e r n s 1 2 Pteridium 1 Sphagnum Ly copodium Unknown s p o r e s 89. P o l l e n assemblage data f o r S t a t i o n 2. May June J u l y Aug. Sept. Oct. Nov. Pinus 21 11 8 Abies Picea Tsuga 2 2 1 1 6 Pseudotsuga 3 - 1 3 Cupressaceae A Inus 4 6 11 1 10 Betula 1 2 Corylus Myrica Rosaceae 8 6 3 1 Sidalcea Soli dago-Achillea 1 11 2 Agoseris 1 43 16 3 1 Aster 1 137 306 428 39 201 Grindelia 41 26 5 Elymus 3 100 19.1 22 28 12 Other grasses 1247 577 126 30 9 79 Rumex 4 4 2 Angelica 30 56 S a l i c o r n i a 7 44 7 2 2 A t r i p lex 5 17 280 147 6 53 V i c i a Plantago 7 5 1 2 Juncus 6 1 Cuscuta Spergularia T r i g l o c h i n 2 2 3 Typha 1 Nuphar Monolete f e r n s •1 2 Pteri di um 1 Sphagnum Lycopodium Unknown spores 90. P o l l e n a s s e m b l a g e d a t a f o r S t a t i o n 2 a . J u n e J u l y A u g u s t S e p t . Pinus 23 20 21 10 Abies 1 1 Picea Tsuga 6 3 6 5 Pseudotsuga 1 C u p r e s s a c e a e A Inus 20 20 37 17 Betula 4 2 Corylus Myrica R o s a c e a e 40 Sidalcea 1 1 Solidago - A c h i l l e a 2 7 Agoseris 1 4 3 2 Aster 2 8 89 246 C r i n d e l i d 4 39 295 Elymus 34 112 9 28 O t h e r g r a s s e s 1081 1083 196 400 Rumez 4 4 Angeliea 5 28 S a l i c o r n i a 7 147 59 57 A t r i p lex 12 138 470 317 V i c i a Plant ago 16 21 Juncus 3 Cuscuta 1 Spergularia T r i g l o c h i n 7 Typha Nuphar M o n o l e t e f e r n s 2 1 1 Pteridium Sphagnum Lycopodium U n k n o w n s p o r e s 1 91. P o l l e n a s s e m b l a g e d a t a f o r S t a t i o n 3. May J u n e J u l y A u g . S e p t . O c t . N o v . Pinus 12 29 .2 4 1 2 Abies Picea Tsuga 2 5 3 1 1 Pseudotsuga 3 1 4 C u p r e s s a c e a e 3 A Inus 11 33 12 11 Betula 1 2 Cory lus 1 Myrica R o s a c e a e 1 7 2 9 Sidalcea Solidago-AchiIlea Agoseris 1 3 7 8 Aster 3 366 359 6 22 Grindelia 36 148 1 Elymus 1 101 133 21 14 2 O t h e r g r a s s e s 4 1002 969 118 69 5 17 Rumex • , 3 Angelica 10 24 Salicornia 1 1 67 236 77 Atriplex 1 2 17 429 359 29 37 Vicia Plantago 1 10 5 1 Juncus Cuscuta Spergularia Triglochin 3 4 Typha 2 Nuphar M o n o l e t e f e r n s Ptevidium . Sphagnum Ly copodium Unknown s p o r e s 92. P o l l e n assemblage data f o r S t a t i o n 3a. June J u l y August Sept. Pinus 5 36 8 Abies Picea Tsuga 7 3 Pseudotsuga 6 1 1 Cupressaceae Alnus 13 27 6 Be t u l a Corylus Myrica Rosaceae 1 26 1 1 Sidalcea Soli dago-Achillea Agoseris 81 57 Aster 4 187 145 Grindelia 38 47 Elymus 124 151 14 1 Other grasses 521 9 82 131 31 Rumex 1 9 1 Angelica 158 226 1 1 S a l i c o r n i a 2 106 174 14 A t r i p lex 8 11 758 389 V i c i a Plantago 11 18 4 1 Juncus Cuscuta Spergularia T r i g l o c h i n 4 Typha 9 Nuphar Monolete f e r n s 1 Pteridium Sphagnum Lycopodium Unknown spores 93. P o l l e n a s s e m b l a g e d a t a f o r S t a t i o n 4. May J a n e J u l y A u g . S e p t . O c t . Nov. Pinus 1 26 24 2 6 2 1 Abies 2 2 Picea Tsuga 4 11 4 1 2 Pseudotsuga 4 2 1 2 1 1 C u p r e s s a c e a e 1 1 .4 Inus 3 63 30 3 1 Betula 2 2 1 1 1 Corylus 1 1 Myrica R o s a c e a e 5 9 1 20 1 Sidalcea Solidago-Achillea Agoseris 4 5 Aster 2 15 4 8 31 Grindelia 5 5 87 291 10 8 Elymus 29 30 5 5 O t h e r g r a s s e s 7 252 360 17 15 10 Rumex 2 5 Angelica 17 10 Salicornia 9 70 252 322 74 15 17-*-Atrip lex 21 329 349 957 904 300 210 Vicia Plantago 4 22 10 Juncus Cuscuta Spergularia Triglochin 3 2 4 3 Typha 1 Nuphar M o n o l e t e f e r n s 1 2 Pteridium Sphagnum Ly copodium Unknown s p o r e s -94. P o l l e n a s s e m b l a g e d a t a f o r S t a t i o n 5. May J u n e J u l y A u g . S e p t . O c t . N o v . Pinus 23 12 1 1 9 Abies 2 2 Picea Tsuga 3 12 2 2 2 5 Pseudotsuga 6 2 1. C u p r e s s a c e a e 2 A Znus 9 20 13 Betula 1 Corylus Myrica R o s a c e a e 3 8 1 Sidalcea Solidago-Achillea Agoseris 1 Aster 2 3 3 17 Grindelia 12 73 73 25 16 E lymus 2 66 80 1 10 1 O t h e r g r a s s e s 2 342 992 20 6 14 Rumex . 1 1 Angelica 2 6 Salicornia 72 94 23 12 18 Atrip lex 2 8 178 1 3 2 5 1071 400 237 Vicia Plantago 31 16 Juncus Cuscuta Spergularia Triglochin 1 17 58 1 2 Typha Nuphar M o n o l e t e f e r n s Pteridium Sphagnum Ly copodium Unknown s p o r e s 95. P o l l e n assemblage data f o r S t a t i o n 6. May June J u l y Aug. Sept. Oct. | Pinus 52 46 23 26 1 Abies i 4 4 Picea 2 Tsuga 20 6 2 2 Pseudotsuga 10 4 1 3 1 Cup r e s s ace ae A.lnus 1 33 16 . 3 9 2 Betula 3 3 Covylus 3 1 Myrica Rosaceae 4 2 2 Sidalcea Solidago-Achillea Agoseris 6 1 1 As ter 1 8 37 Grindelia 1 95 113 4 Elymus 6 23 32 7 12 O t h e r g r a s s e s 4 422 166 42 44 8 Rumex 1 1 ^ Angelica 3 3 S a l i c o r n i a 26 936 415 70 18 A t r i p l e x 2 7 86 824 740 55 V i c i a Plant ago 543 218 6 12 Juncus 6 3 Cuscuta 4 1 6 Spergularia 1 8 T r i g l o c h i n 151 121 18 6 Typha . Nuphar Monolete f e r n s 2 2 3 Pteridium Sphagnum Lycopodium 1 Unknown sp o r e s ) P o l l e n a s s e m b l a g e d a t a f o r S t a t i o n . 7 . 9 6 . May J u n e J u l y A u g . S e p t . Pinus 43 32 13 6 Abies 2 1 Picea 4 . 3 Tsuga 6 8 7 2 1 Pseudotsuga 10 8 1 1 1 C u p r e s s a c e a e 2 Alnus 5 23 13 1 3 Betula 2 2 1 Corylus 1 Myrica R o s a c e a e 1 1 Sidalcea 1 Solidago -Achi Ilea A.goseris 1 1 Aster 1 Grindelia 1 .Elymus 1 35 38 13 4 O t h e r g r a s s e s 19 150 90 58 39 Rumex 1 10 Angelie a 2 Sa l i c o r n i a 8 814 665 305 A t r i p lex 5 34 354 284 Vi cia Plantago 1080 355 7 . 4 Juncus Cuscuta 2 Spergularia T r i g l o c h i n 68 98 6 8 Typha 1 Nuphar M o n o l e t e f e r n s 1 1 Pteridium Sphagnum Ly.copodium U n k n o w n s p o r e s A P o l l e n a s s e m b l a g e d a t a f o r S t a t i o n 8. 9 7 . May J u n e J u l y A u g . S e p t . Pinus 18 185 ~ 101 24 74 Abies 3 12 2 1 Picea 1 18 •7 2 3 Tsuga 24 49 32 8 28 Pseudotsuga 16 36 30 3 7 C u p r e s s a c e a e 6 9 7 1 A Inus 42 230 101 33 66 Betula 6 11 5 4 6 Corylus . 2 5 Myrica N R o s a c e a e 1 2 1 1 Sidalcea Solidago-Achillea Agose ris 2 1 1 Aster 1 1 2 2 Grim.de l i a 1 1 2 Elymus 4 29 30 21 27 O t h e r g r a s s e s 12 24 56 41 45 Rumex 1 1 Angelica S a l i c o r n i a 6 24 46 113 32 Atrip lex 6 16 11 66 33 V i . c i a Plantago 1 15 11 2. 4 Juncus Cuscuta Spergularia 1 T r i g l o c h i n 34 29 25 6 Typha. Nuphar M o n o l e t e f e r n s 4 4 1 18 Fieridium Sphagnum Lycopodium Unknown s p o r e s 1 P o l l e n a s s e m b l a g e d a t a f o r S t a t i o n 9. 98. May J u n e J u l y A u g . S e p t . Pinus 26 168 69 53 35 Abies 4 3 4 Picea 2 23 5 2 3 Tsuga 36 60 61 27 7 Ps eudotsuga 11 42 6 4 1 C u p r e s s a c e a e 8 6 4 1 A Inus 101 120 84 56 36 Betula 6 9 10 4 2 Corylus 1 1 Myrica 2 1 R o s a c e a e 3 1 2 4 Sidalcea Soli dago - A c h i l l e a Agoseris 1 Aster Grindelia 2 Elymus 8 38 25 32 13 O t h e r g r a s s e s 44 53 42 33 42 -Rumex 1 Angelica S a l i c o r n i a 16 14 28 75 10 A t r i p lex 1 7 140 33 V i c i a Plantago 3 2 8 Juncus Cuscuta 4 6 1 SperguI a r i a 1 T r i g l o c h i n 7 6 7 9 Typha 3 1 Nuphar M o n o l e t e f e r n s 1 4 1 1 Pteridium Sphagnum Ly cop odium 2 2 • Unknown s p o r e s P o l l e n assemblage data f o r S t a t i o n 10. 99. • May June J u l y Aug. Sept. Pinus 14 330 133 80 21 A.bies 10 1 4 1 Picea 1 33 13 6 1 Tsuga 21 156 89 42 9 Pseudotsuga 22 26 46 6 4 Cupressaceae 5 8 6 2 A Inus 50 272 134 9 5 73 Betula 5 17 11 10 5 Corylus Myrica 1 1 Rosaceae 2 2 7 4 4 Sidalcea 1 Solidago-Achillea Ag^os e r i s 1 Aster 1 Grindelia 1 Elymus 12 71 89 40 17 Other g r a s s e s 25 126 104 34 22 Rumez 5 4 Angelica S a l i c o r n i a 14 45 67 37 6 A t r i p lex 1 1 3 98 33 Vi cia Plantago 2 2 13 7 . Juncus Cuscuta 19 1 Spergularia T r i g l o c h i n 2 27 23 2 Typha. 1 Nuphar Monolete f e r n s Pteridium 4 5 5 1 Sphagnum Lycopodium 2 Unknown sp o r e s 

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