Shearer, J. I.

Welsh

University of New Brunswick: Centre for Digital Scholarship Journals

R e p o r t s 5 B o t t o m S e d i m e n t s of P o r t a u P o r t B a y , N e w f o u n d l a n d * J . I. S H E A R E R M e m o r i a l U n i v e r s i t y of N e w f o u n d l a n d , S t . J o h n ' s , N f l d . P r o g r e s s R e p o r t D u r i n g t h e s u m m e r of 1966, i n s h o r e m a r i n e g e o l o g i c a l s t u d y w a s u n d e r t a k e n in P o r t au P o r t B a y on t h e w e s t c o a s t of N e w f o u n d l a n d a d j a c e n t to t h e Gulf of S t . L a w r e n c e . T o d a t e t h e s i z e d i s t r i b u t i o n a n d m i n e r a l o g y of s o m e of t h e b o t t o m s e d i m e n t s a m p l e s , b e a c h s a m p l e s a n d p l e i s t o c e n e g i a c i o f l u v i a l s a m p l e s h a v e b e e n a n a l y z e d . In p a r t i c u l a r , a - d e t a i l e d a n a l y s i s of t h e p r o b a b i l i t y p l o t s of t h e s i z e d i s t r i b u t i o n of e a c h s a m p l e i s b e i n g m a d e in a n e f f o r t to f r a c t i o n a t e the s a m p l e i n to i t s c o m p o n e n t p a r t s . T h i s i s done by u s i n g the m e t h o d of f i n i t e d i f f e r e n c e s p r o p o s e d b y W. F . T A N N E R (1959). T h e m a i n a s s u m p t i o n h e r e i s t h a t a l o g - n o r m a l p r o b a b i l i t y c u r v e i s r e p r e s e n t a t i v e of a p o p u l a t i o n in e q u i l i b r i u m w i t h a p a r t i c u l a r e n v i r o n m e n t a n d , t h e r e f o r e , l a f u n d a m e n t a l p o p u l a t i o n of t h a t e n v i r o n m e n t , w h e r e a s a z i g - z a g l o g p r o b a b i l i t y c u r v e i s c a u s e d by m i x i n g i n g i v e n p r o p o r t i o n s of two o r m o r e f u n d a m e n t a l l o g - n o r m a l p o p u l a t i o n s . In t h i s r e s p e c t , w i t h the f e w s a m p l e s ( a b o u t 30) e x a m i n e d in P o r t au P o r t B a y , i t h a s b e e n f o u n d t h a t m a n y of t h e m w h i c h > p o s s e s s d i s s i m i l a r p r o b a b i l i t y p l o t s a r e c o m p o s e d of e s s e n t i a l l y t h e s a m e f u n d a m e n t a l p o p u l a t i o n s of s i l t , f i n e s a n d , c o a r s e s a n d a n d g r a v e l , b u t w i t h t h e r e l a t i v e p r o p o r t i o n s of e a c h f u n d a m e n t a l p o p u l a t i o n v a r y i n g f r o m s a m p l e to s a m p l e . B e f o r e a r e a s o n a b l e i d e a of t he s i g n i f i c a n c e of t h e s e r e l a t i v e c h a n g e s in a b u n d a n c e of f u n d a m e n t a l p o p u l a t i o n s c a n b e o b t a i n e d , m o r e s a m p l e s m u s t b e e x a m i n e d . A s w e l l a s t h i s t y p e of a n a l y s i s , t h e r e g u l a r s t a t i s t i c a l p a r a m e t e r s of m e a n , s t a n d a r d d e v i a t i o n , s k e w n e s s a n d k u r t o s i a r e b e i n g w o r k e d o u t u s i n g t h e a r i t h m e t i c m e t h o d of m o m e n t s . So f a r , b o t h t y p e s of a n a l y s e s i n d i c a t e t h a t m u c h r e w o r k i n g of the s e d i m e n t s in t h e B a y h a v e t a k e n p l a c e a n d , in f a c t , u n d e r t h e s e a no v e s t i g e s of t he o r i g i n a l g l a c i a l t i l l r e m a i n . It h a s b e e n p r e s u m e d , t h a t in t h e d y i n g s t a g e s of W i s c o n s i n g l a c i a t i o n , t i l l w a s d e p o s i t e d in t h e B a y a t a t i m e w h e n t h e l a t t e r s t o o d a b o v e s e a l e v e l a n d s i n c e t h a t t i m e , w i t h the s u b s e q u e n t r i s e in s e a l e v e l due to the m e l t i n g of the g l a c i e r s , t he e n c r o a c h i n g s e a h a s c a u s e d r e w o r k i n g of t h i s o r i g i n a l t i l l . C o m p l i c a t i n g t h i s p i c t u r e i s t he p a s t a n d p r e s e n t i s o s t a t i c r e b o u n d of the l a n d , w h i c h i s r e w o r k i n g the p r e v i o u s l y r e w o r k e d t i l l . M i n e r a l o g i c a l s t u d i e s h a v e to d a t e i n d i c a t e d t h a t t h e r e c e n t s e d i m e n t s in P o r t au P o r t B a y a r e c o m p o s e d m a i n l y of a n a c i d t y p e m i n e r a l s u i t e , b u t t h a t n e a r s h o r e t h i s s u i t e i s m i x e d w i t h , a n d d i l u t e d b y , b a s i c m i n e r a l s f r o m n e a r b y u l t r a - b a s i c o u t c r o p s . P r e s u m a b l y m o s t of t h i s b a s i c m a t e r i a l i s i n t r o d u c e d f l u v i a l l y a n d f r o m d i r e c t e r o s i o n of t h e s e a on r a i s e d p o s t - W i s c o n s i n t e r r a c e s . R e f e r e n c e s c i t e d T A N N E R , W. F . , 1959, S a m p l e c o m p o n e n t s o b t a i n e d by t h e m e t h o d of d i f f e r e n c e s : J o u r n a l S e d i m e n t a r y P e t r o l o g y , v o l . 29, pg . 408-411. * M a n u s c r i p t r e c e i v e d 12 D e c e m b e r , 1966 

Bottom Sediments of Port au Port Bay,   Newfoundland

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Bottom Sediments of Port au Port Bay, Newfoundland

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