Seismic and electrical definition of sand-gravel deposits beneath clay in Essex county, Ontario.

University of Windsor University of Windsor

Scholarship at UWindsor

Scholarship at UWindsor

Electronic Theses and Dissertations Theses, Dissertations, and Major Papers 1-1-1979

Seismic and electrical definition of sand-gravel deposits beneath

Seismic and electrical definition of sand-gravel deposits beneath

clay in Essex county, Ontario.

clay in Essex county, Ontario.

Spiros Vergos

University of Windsor

Follow this and additional works at: https://scholar.uwindsor.ca/etd

Recommended Citation Recommended Citation

Vergos, Spiros, "Seismic and electrical definition of sand-gravel deposits beneath clay in Essex county, Ontario." (1979). Electronic Theses and Dissertations. 6731.

https://scholar.uwindsor.ca/etd/6731

This online database contains the full-text of PhD dissertations and Masters’ theses of University of Windsor students from 1954 forward. These documents are made available for personal study and research purposes only, in accordance with the Canadian Copyright Act and the Creative Commons license—CC BY-NC-ND (Attribution, Non-Commercial, No Derivative Works). Under this license, works must always be attributed to the copyright holder (original author), cannot be used for any commercial purposes, and may not be altered. Any other use would require the permission of the copyright holder. Students may inquire about withdrawing their dissertation and/or thesis from this database. For additional inquiries, please contact the repository administrator via email

SEISMIC A N D E L E C T R I C A L D E F I N I T I O N OF

S A N D - G R A V E L D E P O S I T S B E N E A T H CLA Y

IN ESSEX COUNTY, ONTARIO

b y

Spiros Ve r g o s

A Thesis

s u b m i t t e d to the F a c u l t y of G r a d u a t e Stud i e s through the D e p a r t m e n t of G e o l o g y in Part i a l F u l f i l m e n t

of the req u i r e m e n t s for the Degree of M a s t e r of Science at the

U n i v e r s i t y o f W i n d s o r

Windsor, Ontario, Ca n a d a

UMI Number: E C 547 22

INFO RM ATION TO USERS

The quality of this reproduction is dependent upon the quality of the copy

submitted. Broken or indistinct print, colored or poor quality illustrations

and photographs, print bleed-through, substandard margins, and improper

alignment can adversely affect reproduction.

In the unlikely event that the author did not send a complete manuscript

and there are missing pages, these will be noted. Also, if unauthorized

copyright material had to be removed, a note will indicate the deletion.

UMI Microform E C 5 4 7 2 2 Copyright 2010 by ProQuest LLC

All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code.

ProQuest LLC

789 East Eisenhower Parkway P.O. Box 1346

© S p i r o s Verg o s , 19 79

/

r\

D E D I C A T I O N

T o m y p a r e n t s

A C K N O W L E D G E M E N T S

I g r a t e f u l l y a c k n o w l e d g e Dr. D.T.A. S y m o n s f o r s u g ­

g e s t i n g this t o p i c o f r e s e a r c h a n d fo r h i s t i r e l e s s r e a d i n g

o f the t h e s i s in m a n u s c r i p t . H i s i n v a l u a b l e a s s i s t a n c e in

d r a w i n g u p t h e f i n a l d r a f t o f this th e s i s ha s b e e n g r e a t l y

a p p r e c i a t e d . In a d d i t i o n I t h a n k Dr. M. S t u p a v s k y a n d

Dr. M. B a l l a r g e o n fo r t h e i r a s s i s t a n c e w i t h the c o m p u t e r

t r e a t m e n t o f t h e data. I a l s o t h a n k Dr. D. R u s s e l f o r h i s

c o m m e n t s on this study.

F u r t h e r m o r e I e x p r e s s m y s i n c e r e t h a n k s to m y w i f e

G l e n d a w h o ha s b e e n a c o n s t a n t s o u r c e o f e n c o u r a g e m e n t

A B S T R A C T

S a n d a n d g r a v e l e x i s t in E s s e x County, O n t a r i o , as

p a r a - g l a c i a l d e p o s i t s b e n e a t h lak e c l a y o r g l a c i a l till.

The g e o p h y s i c a l e x p l o r a t i o n for these a g g r e g a t e s is b e ­

c o m i n g a n e c e s s i t y b e c a u s e of the h i g h d e m a n d for t h e m

and o f the n e a r e x h a u s t i o n o f the e x i s t i n g supplies.

S e i s m i c v e l o c i t i e s a n d e l e c t r i c a l r e s i s t i v i t i e s of clay,

s a n d a n d g r a v e l w e r e m e a s u r e d at 50 sites in E s s e x County.

The o b j e c t i v e is to d e f i n e p o s s i b l e r e l a t i o n s h i p s b e t w e e n

t h e s e p a r a m e t e r s .

S e i s m i c v e l o c i t i e s of g r a v e l w e r e n o t f o u n d to b e

s i g n i f i c a n t l y d i f f e r e n t f r o m t h o s e o f clay. Thus, the

s e i s m i c r e f r a c t i o n s u r v e y w i l l n o t b e an e f f e c t i v e g e o ­

p h y s i c a l m e t h o d in the e x p l o r a t i o n o f g r a v e l d e p o s i t s in

E s s e x County. A l t h o u g h the s e i s m i c v e l o c i t i e s o f s a n d

are s i g n i f i c a n t l y d i f f e r e n t f r o m those of clay, san d also

c a n n o t b e r o u t i n e l y d i f f e r e n t i a t e d e i t h e r b e c a u s e of the

large d i s p e r s i o n in its s e i s m i c v e l o c i t i e s .

Th e t hree s e d i m e n t s h a v e s i g n i f i c a n t l y d i f f e r e n t

e l e c t r i c a l r e s i s t i v i t i e s an d r e l a t i v e l y small d i s p e r s i o n

in the e l e c t r i c a l r e s i s t i v i t i e s . This s u g g e s t s tha t

e l e c t r i c a l r e s i s t i v i t y s u r v e y w o u l d b e a n e f f e c t i v e m e t h o d in

d e t e c t i n g g r a v e l a n d s a n d d e p o s i t s u n d e r the c o n d i t i o n s

e x i s t i n g in E s s e x County.

The c o m b i n e d a n a l y s i s of the two m e t h o d s does n o t

i m p r o v e the results o b t a i n e d b y the e l e c t r i c a l r e s i s t i v i t y

m e tho d a l o n e .

T A B L E O F C O N T E N T S

A C K N O W L E D G E M E N T S .

A B S T R A C T ...

L I S T O F A P P E N D I C E S

L I S T O F T A B L E S . .

L I S T O F F I G U R E S .

C h a p t e r

I. I N T R O D U C T I O N ...

1.1 A-im o f the t h e s i s ...

1.2 D e m a n d f o r s a n d a n d g r a v e l d e p o s i t s

1.3 G e o l o g y ...

1 . 3 . 1 B e d r o c k ... 1.3.11 G l e c i a l g e o l o g y o f s o u t h w e s t e r n

O n t a r i o , E s s e x C o u n t y ...

II. G R A I N S I Z E A N A L Y S I S ...

III. S E I S M I C R E F R A C T I O N M E T H O D ...

3.1 T h e o r y ...

3.2 F i e l d w o r k ...

3 . 2 . i I n s t r u m e n t s ... 3 . 2 . 1 1 F i e l d w o r k ...

3.3 D a t a - S t a t i s t i c s ...

IV. E L E C T R I C A L R E S I S T I V I T Y M E T H O D ...

4.1 I n t r o d u c t i o n ...

4.2 P r e v i o u s w o r k ...

4.3 T h e o r y ...

4 . 3 . 1 R e s i s t i v i t y c o n c e p t ...

4 . 3 . 1 1 C o n c e p t o f a p p a r e n t r e s i s t i v i t y . . .

4.4 F i e l d w o r k ... ..

4 . 4 . 1 E l e c t r o d e c o n f i g u r a t i o n ...

4 . 4 . 1 1 I n s t r u m e n t u s e d ... 4 . 4 . i i i G a l v a n i c v o l t a g e a d j u s t m e n t . . . .

4.5 I n t e r p r e t a t i o n o f the a p p a r e n t

r e s i s t i v i t y r e s u l t s ...

4.6 D a t a - S t a t i s t i c s ...

V. I N T E G R A T E D A N A L Y S I S ...

5.1 I n t r o d u c t i o n ...

5 . 2 . 1 1 D i s c u s s i o n o f the r e s u l t s ... . 3 2

5 . 3 . i R e s i s t i v i t y v s g r a i n size. ... 5 3

5 . 3 . 1 1 D i s c u s s i o n of t h e r e s u l t s ... ^ 7

5.4 R e s i s t i v i t y v s s e i s m i c v e l o c i t y . . . . 6l

VI. C O N C L U S I O N S ...6 5

R E F E R E N C E S ...67

A P P E N D I X I: G r a i n s i z e a n a l y s e s ... 70

A P P E N D I X I I : S e i s m i c v e l o c i t i e s ... 81

A P P E N D I X III: A p p a r e n t r e s i s t i v i t i e s ... 11^+

A P P E N D I X IV: D e r i v a t i o n o f e q u a t i o n (4.3.2) . . . •.•131

A P P E N D I X V: I n t e g r a t e d a n a l y s e s - G r a p h s ... I3J4.

L I S T O F A P P E N D I C E S

A P P E N D I X I: G r a i n siz e a n a l y s e s ... 70

A P P E N D I X II: S e i s m i c v e l o c i t i e s ... 8l

A P P E N D I X III: A p p a r e n t r e s i s t i v i t i e s ... i\L\.

A P P E N D I X IV: D e r i v a t i o n o f e q u a t i o n (4.3.2) . . . . 1 3 1

A P P E N D I X V: I n t e g r a t e d a n a l y s e s - G r a p h s ... 1324.

A P P E N D I X VI: I n s t r u m e n t s u s e d ... 168

L I S T O F T A B L E S

p a g e

T a b l e A. L i s t o f the s y m b o l s u s e d in the t e x t ...

T a b l e 1. T o n n a g e a n d $ v a l u e o f s a n d a n d

g r a v e l p r o d u c e d in O n t a r i o ... 9

T a b l e 2. S u b d i v i s i o n s o f the Q u a t e r n a r y i c e

-age in s o u t h w e s t e r n O n t a r i o ... 2.2

T a b l e 3. G r a i n s i z e a n a l y s e s r e s u l t s ... 2 . 8

T a b l e 4. S e i s m i c v e l o c i t i e s of a l l s i t e s ... ^0

T a b l e 5. M e a n a n d d e v i a t i o n s t a t i s t i c s

f o r the s e i s m i c v e l o c i t i e s ... - . . 3 1

T a b l e 6 . G r o u p c o r r e l a t i o n s t a t i s t i c s

for the s e i s m i c v e l o c i t i e s ... 3 1

T a b l e 7. S u m m a r y o f t h e i n t e r p r e t e d

r e s i s t i v i t y d a t a ...

T a b l e 8 . M e a n a n d d e v i a t i o n s t a t i s t i c s

for e l e c t r i c a l r e s i s t i v i t i e s ... Ij, 6

T a b l e G r o u p c o r r e l a t i o n s t a t i s t i c s

for e l e c t r i c a l r e s i s t i v i t i e s ... j

T a b l e 10. L o g p v a l u e s f o r GRAV E L , S A N D a n d CLAY. . . . 5 0

T a b l e 11. G r a i n s i z e a n a l y s e s f o r G R A V E L ... 7 1

T a b l e 12. G r a i n siz e a n a l y s e s f o r S A N D ... r?2

T a b l e 13. G r a i n size a n a l y s e s f o r C L A Y ... 7 3

T a b l e 14. G r a i n s i z e p l o t s i n c l u d e d in A p p e n d i x I . . .

T a b l e 15. M e a s u r e d t r a v e l - t i m e s a n d c a l c u l a t e d

s e i s m i c v e l o c i t i e s for 26 sites ... 8 2

T a b l e 16. S e i s m i c r e c o r d s i n c l u d e d in A p p e n d i x II . . . g^

T a b l e 17. A p p a r e n t r e s i s t i v i t y r e s u l t s ...2 . 1 5

T a b l e 18. A p p a r e n t r e s i s t i v i t y . P l o t s i n c l u d e d

in A p p e n d i x I I I ...122

T a b l e 19. I n t e g r a t e d a n a l y s e s . P l o t s i n c l u d e d

in A p p e n d i x V ... 13 5

L I S T O F F I G U R E S

p age

F i g u r e 1. E s s e x C o u n t y , r e f e r e n c e m a p ... $

F i g u r e la. S a m p l e s i t e s n e a r W i n d s o r ... 6

F i g u r e lb . S a m p l e s i t e s n e a r L e a m i n g t o n ... 7

F i g u r e 2. M i n e r a l a g g r e g a t e u t i l i z a t i o n p a t t e r n

fo r O n t a r i o ... 9

F i g u r e 3. I c e - f r o n t p o s i t i o n at the t i m e s o f L a k e

W h i t t l e s e y a n d L a k e W a r r e n ... lij.

F i g u r e 4. P a r t i c l e s i z e d i s t r i b u t i o n for

five s a m p l e s ... 1 9

F i g u r e 5. R a y p a t h s o f l e a s t t i m e fo r t w o l a y e r s . . . 21

F i g u r e 6 . T i m e - d i s t a n c e c u r v e f o r two l a y e r s ... 21

F i g u r e 7. T y p i c a l r e c o r d f r o m the F S - 3 ... 2^

F i g u r e 8 . H i s t o g r a m s fo r the s e i s m i c v e l o c i t i e s . . . . 2 7

F i g u r e 9. G e n e r a l i z e d e l e c t r o d e c o n f i g u r a t i o n ... ^

F i g u r e 10. E l e c t r o d e a r r a n g e m e n t f o r the W e n n e r

c o n f i g u r a t i o n ... ^ 5

F i g u r e 11. V a r i o u s m u l t i l a y e r p r o f i l e s f o r p ... 1\.q

U

F i g u r e 12. E x a m p l e o f a p p a r e n t r e s i s t i v i t y

i n t e r p r e t a t i o n ... 14. 0

F i g u r e 13. H i s t o g r a m s f o r th e e l e c t r i c a l

r e s i s t i v i t i e s ... I4.3

F i g u r e 14. % S a n d vs V e l o c i t y p l o t f o r a l l s a m ples. . . Ij. 9

F i g u r e 15. % S a n d v s l o g V p l o t f o r a l l s a m p l e s . . . .

F i g u r e 16. % G r a v e l vs V e l o c i t y p l o t f o r S A N D

an d G R A V E L ... 5 1

F i g u r e 17. % C l a y vs lo g V p l o t f o r the C L A Y group. . .

F i g u r e 18. % G r a v e l v s l o g p p l o t f o r S A N D

a n d G R A V E L ... 5 5

F i g u r e 19. R e g r e s s i o n line, s e c o n d a n d t h i r d -d e g r e e p o l y n o m i a l s f o r % G r a v e l

a n d log p ... 5 6

F i g u r e 20. % S a n d vs l o g p f o r a l l s a m p l e s ...5 8

F i g u r e 21. I n t e r v a l s f o r log p v a l u e s ...

F i g u r e 22. L o g p v s l o g V p l o t f o r al l s a m p l e s . . . . 5 3

F i g u r e 23. B o u n d a r y l i m i t s o f l o g V, lo g p for

G R A V E L , S A N D a n d C L A Y ... 6 3

F i g u r e 24. (24.1-24.6). G r a i n s i z e v s c u m u l a t i v e

pe r c e n t a g e ... 7 5

F i g u r e 25. (25.1-2 5.24). F S - 3 s e i s m i c r e c o r d s . . . . g0

F i g u r e 26. (26.1-26.7). I n t e r p r e t a t i o n o f

a p p a r e n t r e s i s t i v i t y d a t a ... 1 2 3

F i g u r e 27. C u r r e n t l ines f r o m a p o i n t c u r r e n t

s o u r c e ... 1 3 2

F i g u r e 28. (28.1-2 8.32). I n t e g r a t e d a n a l y s i e s . . . . 1 3 6

F i g u r e 29a. F S - 3 s e i s m o g r a p h ... 1 6 9

F i g u r e 29b. R e s i s t i v i t y i n s t r u m e n t ... 1 7 0

TABLE A

L i s t of the symbols u s e d in the text

a e l e c t r o d e s e p a r a t i o n for W e n n e r "spread" in

c c o r r e l a t i o n c o e f f i c i e n t

D .f . d e g r e e s of f r e e d o m

F the F - s t a t i s t i c

F.(r's) Roman's form factor

i angle of inc i d e n c e of a s e i s m i c wav e

i critical angle

I e l e c t r i c a l c u r r e n t in m i l l i a m p e r e s

1 length in m

m meter(s)

tt 3.14

P the t w o -tail s i g n i f i c a n c e level

r e l e c t r o d e sepa r a t i o n in m

r' angle of r e f r a c t i o n

P r e s i s t i v i t y in o h m - m

Pa a p p a r e n t r e s i s t i v i t y in o h m - m

R r e s i s t a n c e in o h m

S c r o s s - s e c t i o n a l area in m

T arri v a l time of a seismic w a v e

i n t e r c e p t time of a seismic w a v e

T the T - s e p a r a t e sta t i s t i c

V v e l o c i t y in m / s e c of a seismic pulse

V v o l t a g e in m i l l i v o l t s

X s h o t - p o i n t - g e o p h o n e d i s tance in m

c r i tical d i s t a n c e in m

Z d epth to an int e r f a c e f r o m surface in m

C H A P T E R I

I N T R O D U C T I O N

S a n d a n d g r a v e l ar e i m p o r t a n t i n d u s t r i a l r e s o u r c e s

p r o d u c e d in O n t a r i o . T h e y ar e u s e d as a g g r e g a t e in v a ­

r i o u s t y p e s of c o n s t r u c t i o n t o g e t h e r w i t h c r u s h e d stone.

N e w d e p o s i t s are in d e m a n d b e c a u s e l a r g e a m o u n t s o f s a n d

a n d g r a v e l are u s e d e v e r y year, a n d e c o n o m i c a l d e p o s i t s

are b e i n g r a p i d l y d e p l e t e d .

In E s s e x C o u n t y s a n d a n d g r a v e l d e p o s i t s are l o c a t e d

m a i n l y n e a r L e a m i n g t o n . T h e y are a s s o c i a t e d w i t h the

E s s e x m o r a i n e w h i c h w a s d e p o s i t e d d u r i n g the r e t r e a t of

the ic e w h i c h c o v e r e d th e a r e a in the P l e i s t o c e n e Epoch. The

s a n d a n d g r a v e l are d e p o s i t e d on th e s i d e s a n d s h o u l d e r s

o f the m o r a i n e b y the l a k e s w h i c h c o v e r e d E s s e x C o u n t y

a f t e r t h e r e t r e a t o f the ice. T h e s e l a k e s a l s o l e f t s h a l ­

l o w l a c u s t r i n e c l a y o v e r l y i n g the s a n d a n d g r a v e l d e p o s i t s .

G e n e r a l l y the d i f f e r e n t e l a s t i c a n d e l e c t r i c a l p r o ­

p e r t i e s o f clays, s a n d s a n d g r a v e l s m a y b e u s e d to d i f f e r ­

e n t i a t e b e t w e e n t h e s e s e d i m e n t s . The o b j e c t i v e o f this

s t u d y is to look for p o s s i b l e c o n t r a s t s in s e i s m i c v e l o c i ­

ties an d e l e c t r i c a l r e s i s t i v i t i e s b e t w e e n the clays, s a n d s

and g r a v e l s in E s s e x County. If f a v o u r a b l e c o n t r a s t s do

e x i s t t h e y m i g h t b e u s e d in g e o p h y s i c a l e x p l o r a t i o n f o r

n e w s a n d a n d g r a v e l d e p o s i t s .

S e i s m i c v e l o c i t i e s a n d e l e c t r i c a l r e s i s t i v i t i e s w e r e

m e a s u r e d at 50 s i t e s in E s s e x C o u n t y o v e r a w i d e r a n g e o f

p h y s i c a l c o n d i t i o n s o f the s p e c i f i c sediment. V a r i o u s

s t a t i s t i c a l a n d r e g r e s s i o n c o m p u t e r p r o g r a m s w e r e u s e d

in the s e a r c h o f p o s s i b l e r e l a t i o n s h i p s b e t w e e n the t ype

of sediment' a n d its s e i s m i c v e l o c i t y and e l e c t r i c a l r e ­

sistivity.

1.1 A i m o f the t h e s i s

It is g e n e r a l l y b e l i e v e d t h a t the s e i s m i c v e l o c i t i e s

of c l a y s are h i g h e r than the s e i s m i c v e l o c i t i e s of sands

and g r a vels. It is als o b e l i e v e d , a n d j u s t i f i e d f r o m

t h e o r y a n d e x p e r i e n c e , tha t the e l e c t r i c a l p r o p e r t i e s o f

the m i n e r a l s f o r m i n g c l a y s ar e s i g n i f i c a n t l y d i f f e r e n t

than t h o s e of the m i n e r a l s f o r m i n g sands a n d gravels.

H o w e v e r u n e x p e c t e d c h a n g e s in c o m p o s i t i o n o r c o m p a c t i o n

m i g h t p r o d u c e u n e x p e c t e d g e o p h y s i c a l p r o p e r t i e s in a p a r ­

t i c u l a r sediment.

W h e n s a n d g r a v e l d e p o s i t s e x i s t in E s s e x County,

t hey u s u a l l y o c c u r b e n e a t h 1 to 3 m of c l a y a n d o v e r l i e

o l d e r till. The s e i s m i c v e l o c i t i e s a n d the e l e c t r i c a l

r e s i s t i v i t i e s of sands, g r a v e l s a n d c l a y s w e r e m e a s u r e d

in thi s s t u d y to see w h e t h e r o r n o t t hey c a n b e u s e d to

d i f f e r e n t i a t e the a b o v e sedim e n t s .

B e c a u s e the s e i s m i c v e l o c i t i e s o f the o v e r l y i n g

c l a y s a r e u s u a l l y g r e a t e r t h a n t h o s e o f s a n d a n d / o r

gravel, the l a t t e r c o n s t i t u t e s a h i d d e n l a y e r u s i n g the

s e i s m i c r e f r a c t i o n m e t h o d . F o r a g i v e n s e q u e n c e o f

layers, a h i d d e n l a y e r (or l o w - s p e e d l a y e r (Dobrin, 19 76)

o r h i d d e n - z o n e (Telford, 1977)) is d e f i n e d as one t h a t h a s

a l o w e r s e i s m i c v e l o c i t y than the o n e a b o v e it. S u c h a

b e d in t h e s e q u e n c e "will n o t b e d e t e c t a b l e b y r e f r a c t i o n

s h o o t i n g at all" (Dobrin, 19 76). T his is a d i f f e r e n t s i ­

t u a t i o n f r o m a "blind zone" w h e r e th e s e c o n d l a y e r also

does n o t a p p e a r o n the s e i s m i c record. A b l i n d zone is

a l a y e r w h i c h is v e r y thin and, a l t h o u g h it h a s g r e a t e r

s e i s m i c v e l o c i t y than the on e a b o v e it, i t is n o t d e t e c ­

table b e c a u s e o t h e r s e i s m i c e v e n t s suc h as r e f r a c t e d w a v e s

f r o m d e e p e r l a y e r i n t e r f a c e s m a s k the r e f r a c t e d w a v e s f r o m

the "b l i n d zone". This d i s t i n c t i o n b e t w e e n a "hidden

layer" a n d a "blind zone" is n e c e s s a r y b e c a u s e some w r i t e r s

(Green, 1962 ; G r i f f i t h s , 1975 ; H a w k i n s , 1960 ; Morgan,

1966 ; Soske, 1959 ) i n t e r c h a n g e t h e i r d e f i n i t i o n .

W h e n t h e s e i s m i c r e f r a c t i o n m e t h o d is used, s a n d o r

g r a v e l h i d d e n la y e r s do n o t a p p e a r on the t i m e - d i s t a n c e

s e i s m i c record. The t h e o r e t i c a l e x p l a n a t i o n w i l l b e g i v e n

in c h a p t e r 3.1.

W h e n the s e i s m i c r e f l e c t i o n m e t h o d is u s e d o n l y the

l o w e r i n t e r f a c e o f s a n d a n d g r a v e l l a y e r m a y g i v e a r e ­

f l e c t i o n on the s e i s m i c record. W h e n t h e r e is l i t t l e or

ho i m p e d a n c e c o n t r a s t b e t w e e n two layers, the n v e r y l i t t l e

o r n o r e f l e c t e d e n e r g y w i l l r e t u r n f r o m the l o w e r i n t e r ­

face.

In g e n e r a l s ands a n d g r a v e l s are p o o r e l e c t r i c a l c o n ­

d u c t o r s b e c a u s e t h e y are u s u a l l y h i g h in q u a r t z c o n t e n t

an d lac k s o l u b l e salts. C l a y s o n th e o t h e r h a n d are m u c h

b e t t e r e l e c t r i c a l c o n d u c t o r s b e c a u s e t h e y u s u a l l y c o n t a i n

a b u n d a n t solu b l e salts. Thus c o n d u c t i v i t y , o r its r e c i p ­

r o c a l r e s i s t i v i t y , c a n also b e u s e d to d i f f e r e n t i a t e s ands

an d g r a v e l s f r o m clays.

F i f t y s ites w e r e s e l e c t e d (Fig. 1, la, lb) at w h i c h

s e i s m i c v e l o c i t i e s a n d e l e c t r i c a l r e s i s t i v i t i e s w e r e m e a ­

sured. A r e p r e s e n t a t i v e s a m p l e w a s a l s o t a k e n to b e u s e d

for g r a i n size a n a lysis. The s e l e c t e d s i t e s e x h i b i t e d a

w i d e r a n g e of p h y s i c a l c o n d i t i o n s f r o m "moist" to "dry"

c o n d i t i o n s . S u c h c o n d i t i o n s w e r e c h o s e n to g i v e a c h a r ­

a c t e r i s t i c r e p r e s e n t a t i o n o f the s e d i m e n t r e s p o n s e to

s e i s m i c v e l o c i t i e s a n d e l e c t r i c a l r e s i s t i v i t i e s as they

m i g h t b e e n c o u n t e r e d in the g e o p h y s i c a l e x p l o r a t i o n for

s a n d an d g r a v e l deposits.

The s e i s m i c v e l o c i t i e s , e l e c t r i c a l r e s i s t i v i t i e s a n d

g r a i n s i z e r e s u l t s w e r e s u b j e c t e d to v a r i o u s s t a t i s t i c a l

t e s t s in an a t t e m p t to d e f i n e an y e x i s t i n g q u a n t i t a t i v e

r e l a t i o n s h i p s .

1.2 D e m a n d for s a n d a n d g r a v e l d e p o s i t s

The c o n s t r u c t i o n an d p a v i n g i n d u s t r i e s are th e p r i n ­

c i p a l c o n s u m e r s o f s a n d a n d grav e l . T h e y r e q u i r e i n c r e a s ­

i n g t o n n a g e s o f t h e s e two t y p e s o f m i n e r a l a g g r e g a t e e a c h

y e a r f o r v a r i o u s t y p e s o f c o n s t r u c t i o n in O n t a r i o as s h o w n

in Fig. 2. T y p i c a l use s i n c l u d e p o r t l a n d - c o n c r e t e a g g r e ­

gate, p a v i n g , h i g h w a y s , dams, a i r p o r t r u n w a y s , piers,

CO

w

CM CM

CM rH

M

•H

■P _•H

CO

• tH o

+».

•H CM

CO CO

CO

CO

5

F

i

g

.

1.

E

s

s

e

x

C

o

u

n

t

y

r

e

f

e

r

e

n

c

e

n

a

p

CV

—

cm m

»CJ cr\

o

o

On

NO

CM

CO

O i—I

CO CM On

W •H

P-£

•rt

W cd 'O

£

0) to 03

u

O n 'CJ

£

£

in o -P •H O <u

I—I

£

cl

to

cl

hO •H

Ph

o o O O CO o CM CM +» t}0 CM CM O On

1 CM

M

CO _{E s s e x R o a d 31}

house foundations, buildings and sewers. In the years

1974-1977, for example, sand and gravel rank second after

cement among Ontario industrial mineral products (Table 1).

7 0 . 3 x 1 0 6 tons of sand and gravel were p r o d u c e d in Ontario

with a value of 1 1 2 x 1 06 dollars. Thus they are of great

economic importance. Demand for sand and gravel is e x ­

pected to increase a n n u a l l y w i t h a 55% increase p r o ­

jected by the year 2000 (Proctor and Redfern Ltd, 1975).

The production statistics represent an over-all p i c ­

ture for Ontario. However the distribution of sand and

gravel deposits is n o t uniform. In m o s t counties the su p ­

ply is less than the demand. Thus sand and gravel is m oved

from one county to another or even imported from the Uni t e d

States of America. In either case their cost to the co n ­

sumer increases.

For Essex County the total possible reserves for sand

and gravel were estimated at only 2 5 3 . 3 x 1 0 6 tons in 1975

(Proctor and Redfern L t d . , 19 75). M o s t of these reserves

are in ths southeast corner of the county near Leamington.

Hence sand and gravel m u s t be trucked a bout 50km to Windsor

w h i c h is the m o s t significant m a r k e t in the county. A l t e r ­

natively Windsor consumers use crushed aggregate from

quarries around Amherstburg w h i c h are about 20km away.

Aggregate reserves stood at about 3 , 0 5 8 x 1 0 6 tons in 1975.

Finally sand and gravel or aggregate may be imported into

Windsor from the United States of America. In 1975, for

R . B . = R e s i d e n t i a l Building.

N .R .B .= N o n - r e sidential Building.

R . E . = R o a d Engineering.

K . R . E . = N o n - r o a d Engineering.

Fig. 2. Kineral aggregate utilization pattern for

Ontario’s 1971 total of 77,631,000 tons after

Proctor and Redfern Ltd (1975)*

Y e a r Tons $ Value

1974 79,712,838 85,104,576

1975 69,705,434 95,578,927

1976 68,802,045 1 0 6 ,093,326

1977 • 70,306,817 112,400,000

Table 1. Tonnage and $ Value of sand and gravel

produced in Ontario.

example, about 493,000 tons were imported w i t h a value of

$1.80 to $2.50 per ton. This compares to $0.73 per ton

at the source near Leamington and Amherstburg.

Although the importance of discovering new deposits

in Ontario is not questioned, "no individual deposit is

necessarily m i n e d just because it exists" (Ontario Dept,

of Mines, 1975). Sterilization of large deposits has r e ­

sulted because of zoning restrictions in urban areas or

of development of the land for other purposes. The e n ­

vironmental costs mus t be traded off against the cost of

moving sand and gravel especially by trucks. Trucking

costs were at about $0.12/ton mile in Ontario in 1975

(Ontario Dept, of Mines, 1975).

1.3 Geology

1.3.i Bedrock in Essex County

The basement in Essex County is composed of Precambrian

rocks of the Grenville geologic province. Overlying the

b a s ement are four flat lying Paleozoic Devonian formations:

1) the Detroit River formation composed of brown to buff

limestone, dolomite and sandstone; 2) the Columbus forma­

tion composed of grey to buff sandy limestone and dolomite;

3) the Delaware formation composed of brown to buff lime­

stone with some chert; and 4) the Hamilton formation c o m ­

posed of grey shale and argillaceous limestone (Geological

Survey of Canada, 1958). These sediments are covered by

about 30m of Quaternary drift except near Amherstburg

where the Devonian sediments come to the surface.

1.3.ii, Glacial Geology of Southwestern Ontario-Essex

County

All of the known sand and gravel deposits in

south-western Ontario are associated w ith the Pleistocene Epoch.

During this epoch large ice-sheets advanced and retreated

over the area several times. The main sources for sand

and gravel deposits are the resulting moraines and eskers

although some spillways and kames have also produced quite

large deposits.

The glacial history and deposits of southwestern

Ontario have been described in detail b y Chapman (1969),

He w i t t (1963) and Taylor (1913). A summary of the events

affecting the formation of these sand and gravel deposits

f o l l o w s .

There were four major cold glacial stages in the

Pleistocene Epoch during which the ice advanced (Hewitt,

19 63). The intervals between the ice advances were c h a r ­

acterized by interglacial stages that wer e as w a r m or

even w a r m e r than the present climate. These subdivisions

of the Quaternary ice age are shown in Table 2. Economic

pre-VJisconsinan sand and gravel deposits are very rare in

Ontario and "they can be disregarded w h e n describing the

surface features" (Chapman, 1969) .

C 1** dating studies on p lant remains (Goldthwait,

1973) have established that the Wisconsin ice-sheet had

p e r i o d e p o c h GLACIAL STAGES INTERGLACIAL STAGES

HOLO-CENE _Recent

VJisconsinan

Sangamonian

I llinoian

Yarmouthian

K a n s a n

A f t onian

N eb r a s k a n

Table 2. Subdivisions of the Q u a t e r n a r y ice age in

southwestern Ontario.

covered all of southern Ontario b y 20,000 years ago. This

area remained under the ice until about 14,000 years ago.

With the subsequent retreat of the ice, large meltwater

streams left sand and gravel in deposits such as the

Waterloo kame accumulation and the Orangeville moraine. The

ice melted progressively to the north.

One of the recessional moraines left during the re­

treat was Essex moraine. This moraine was first described

by Taylor (1913) as "extending from Detroit southwestward

through Essex tc the high knoll w e s t of Leamington, and

being a low broad ridge of till, very smooth and with such

gentle slopes as to b e quite inconspicuous to the eye as a

r i d g e ” .

By about 13,000 years ago Lake Whittlesey covered all

of southwestern Ontario (Fig. 3). This lake left a p r o ­

min e n t shoreline in southwestern Ontario which is preserved

as beach deposits lagging around the Essex moraine. These

deposits have been sources for sand and gravel such as the

Erie San d and Gravel deposit (e.g. sites 1, 11, 12, 13, 14,

16 in Fig. l b ) . Mos t of Essex County was under water during

the life of this lake.

The next prominent lake was Lake Warren which also

covered m o s t of southwestern Ontario (Fig. 4). It also

left sand and gravel beach deposits on the shoulders of

the Essex moraine such as the deposit operated by Kennette

Co. lot 1 concession IV, Mersea township, Essex (e.g.

P ro d u c e d

WHtTTLtStr

Kl

Pig. 3 . Ice-front position at the time of s

A) Lake Whittlesey and B) Lake Warren;

after Hewitt (1963 ) •

Ik

sites 2, 24, 25, 32)<>

L e v e r e t t and Taylor (1915) have recognized one more

successor lake in the County, namely Lake Grassmere, at

about 15m lower altitude. They consider the gravel bar

on the crest of the moraine to be "a Grassmere storm

beach".

A l l of these lakes left b each deposits around the

sides and the shoulders of the Essex moraine. Thus the

moraine is bounded b y sand and gravel except at its h i g h ­

est p o i n t just north of Ruthven where it is composed e n ­

tirely of till.

The Essex till plain (Chapman, 1969) was deposited

under the ice. Lake Whitt l e s e y and Lake Warren failed

to leave any deep stratified beds on the till plain

(Chapman, 1969). The plain was smoothed by shallow d e ­

posits of lacustrine clay from the lakes w h i c h settled

in the depressions while the knolls were being lowered

by wave action.

C HAPTER II

GRAIN SIZE ANALYSIS

At each site a 2 to 3kg sample was taken at a depth

of about 0.4m b elow the surface. A representative sub­

sample of 600-700g was then split from it using the q u a r ­

tering method. This subsample was used for the grain

size analysis. The cumulative percentage of gravel, sand

and clay were then calculated.

The Wentworth classification was use d to define the

Percentage of sand, gravel and clay contained in the s a m ­

ples because it is "the classification commonly accepted

by geologists" (Bates, 1969). Thus the dividing line b e ­

tween sand and gravel was set at the 2m m diameter sieve

size and between sand and clay at the 0.074mm diameter

sieve size, i.e. #10 and #200 in the U.S. Sieve series

respectively. It m u s t be n o t e d though that different

limiting diameters are o ften assigned to sand and gravel

by high w a y departments, engineering organizations and v a ­

rious o ther government agencies.

The first 32 samples of Table 3 contain less than 1%

silt o r clay and so were divi d e d into two groups. The

GRAVEL group includes samples w i t h >50% of the particles

°f £2mm size while the SAND group includes samples w i t h

>50% of the particles between 2m m and 0.074 m m in size.

In Table 3 the numerical values of the "% gravel" and "%

sand" have bee n rounded off to the closest integer

elud i n g the <1 % clay.

Th e r e m aining 18 samples cons i s t of silt and c l a y w i t h

>50% of the p a rticles finer than 0.074mm. These samples

form the C L A Y group. The field term CLAY is u s e d for

the silt and c lay f r a ction t h a t overlies the sand an d

gravel deposits in E s s e x County. The e x a c t p e r c e n t a g e s

of silt (between 0.07 4 m m to 0.005mm) an d clay (less than

0.005 mm) va r i e s f r o m . 60-100% w i t h sand c o n s t i t u t i n g the r e ­

m a i n i n g 40-0%. The clay fraction of similar d e p o s i t s in

the W i n d s o r are a varies f rom 20-80% w i t h an aver a g e value

of a b o u t 40% (Wilkinson, 1978).

The results of the g rain size analyses are shown in

w e i g h t p e r c e n t a g e s on Table 3. Fig. 4 shows a gra p h i c a l

^ p r e s e n t a t i o n o f p a r t i c l e size p l o t t e d agai n s t c u mulative

P e r c e n t a g e for five typical samples.

g r a v e L S A N D C L A Y

Site erf

7° % Site % % Site

cf 7°

# gravel sand 7

?

1 _{52 48} 16 ₉₉ 1 _{33 85 15}

2 _{62 38 17 78 22 ' 3^ 78 22}

3 60 40 18 82 18 ₃₅ 68 32

4 _{52 48 19 98 2 36 66 34}

5 56 44 20 98 2 ₃₇ 68 32

6 _{56 44 21 99 ' 1 38 68 32}

7 56 44 22 70 30 39 79 21

8 _{56 44 23 88 12 40 84 16}

9 ₅₂ 48 24 97 3 4l 62 38

10 _{50 50}

25 84 16 42 61 ₃₉

11 _{52 48 26 68 32 43 66 34}

12 _{66 3^ 27 82 18 44 61 39}

13 70 30 28 ₉₉ 1 45 _{73 27}

14 _{68 32 29 97 3 46}

75 25

15 62 38 30 _{95 5 47} 90 10

31 99 1 48 92 8

•

32 _{95 5} 49 ₇₉ 21

50 _{.. 6 2 _______} 37

Table 3. Grain-size analyses for samples from 5° sites in Essex

Re

pr

od

uc

ed

w

ith

pe

rm

is

si

o

n

of

th

e

co

py

ri

gh

t

o

w

ne

r.

Fu

rthe

r

rep

roduction

p

ro

h

ib

it

e

d

wi

th

ou

t

p

e

rm

is

s

io

n

.

i- 1

VO

S ieve S iz e s ( U .S. Standard)

? A " 3/ 8* A #8 #16 #30 #50 #100 #200

_> I______________• ■ * - - ■ - ---- - ■ ‘ 1 * ₇₁₀₀

ASite 3

• Site 13

ASite 17

oSite 18

aSite 3°

10 5

millimeters

C HAP T E R III

SEISMIC REFRACTION METHOD

3.1 Theory

T he seismic refraction m e t h o d of p rospecting g e n e r ­

ally uses waves generated at surface although subsurface

sources may be used in some oil exploration or submarine

studies. These waves are p r o d u c e d b y various methods

ranging from a simple sledge ha m m e r to powerful explosives.

In this study the energy source was a sledge hammer

striking a m e t allic plate on surface.

F i r s t consider the case where the subsurface c o n ­

sists of two m e d i a w i t h unif o r m elastic properties and

separated by a horizontal interface at depth Z (Fig. 5).

Let the velocity of the longitudinal seismic w a v e be Vi

in the upper layer and V2 in the lower layer w ith V2>Vi.

Suppose that a seismic wave is g e nerated at p o i n t A on

the surface. This wav e radiates out from point A in all

directions as an expanding hemispherical front in the

homogenous, upper layer. Once the radius of the front

becomes relatively large then the front can be treated

as a plane. Lines p e r p e n d i c u l a r to the w a v e front r e ­

present the direction of propagation and are called

"paths" or "rays". In Fig. 5 fronts are represented by

these "rays".

W h e n the seismic w ave g e n e r a t e d a t A reaches the

interface at p oint Bi w i t h an incident angle (i), some

Fig. 5 * R a y p a t h s of l e a s t time fo r two layers

sep a r a t e d by a h o r i z o n t a l i n t e r f a c e a t d e p t h Z.

The remaining symbols are given in the text.

1

s l o p e = l / v T

1

X_{c X}

Fig. 6. Time-distance curve for two layers separated

a h o r i z o n t a l i n t e r f a c e a t d e p t h Z . T is the arri v a l

time of the f i r s t e n e r g y p u l s e of a w a v e f r o n t at distance

X f r o m the s o u r c e . Th e r e m a i n i n g s y m b o l s are g i v e n i n the

t e x t .

°f its energy is reflected back to surface. The rest of

its energy refracted into the lower m e d i u m at an angle

(r^) w h i c h satisfies Snell's law:

Sln(1) = (3.1)

sinfr"') V 2

in the special case where r'' = 90° equation (1) gives

ic = sin (Vi/V2) (3.2)

This angle (i ) is called the critical angle. A t i the

c c

incident wave is refracted along the interface and travels

in the lower layer at a velocity V 2 . At any point C the

wave is subjected to Huygen's principle and is refracted

back upwards into the upper layer. According to Huygen's

Principle every point on a wave front is the source of a

new w ave that also travels out from the p o i n t in spherical

shells. Consequently all points on the interface are

sources of new waves, and some of their energy travels t o ­

wards the surface. The energy leaving C at the angle i

C*

ls then detected first at point D.

At any point on surface between A and D the wave

travelling directly through the first layer w i l l arrive

first at a detector. This happens because the path AD is

sufficiently shorter than A B C D to compensate for the lower

velocity. At p o i n t D the travel times of both direct

wave travelling through the u pper layer and the refracted

wave travelling along the path A BCD are equal. Beyond

point D the refracted w a v e travels faster and arrives

first at the detector. The distance AD is called the

critical distance (X ). c

Pig. 6 is an illustration o f the time-distance curve

for the case of a detector m o v e d out to wel l beyond Point

D. The slopes of the two linear segments are equal to

the inverse of the layer velocities, i.e. 1/Vi and I / V2 .

The intercept time (T^) is w h e r e the 1 / V2 segment projects

to the time axis.

W h e n V i > V 2 , then from equation (3.1) r<i so that it

is impossible to refract a wave along the interface. In

this case all energy is refracted into second layer at a

steeper angle than the i n c i d e n t angle. Thus that i n t e r ­

face does not show on the time-distance curve. This is

the hi d d e n layer case w h i c h obviously cannot be solved

using the refraction m e t h o d alone.

3.2 F i e l d Work

3.2.i Instruments Use d

Two instruments were used in the course of collecting

the field data. The S o i ltest R-117B Seismic Timer is a

small, portable, self-powered instrument. It records only

the time r e q uired b y the first pulse of ene r g y to travel

from the shot p o i n t to the single geophone. The Huntec

F S-3 Seismograph, (Appendix V I ) , is also a portable and

self-powered instrument. It records automatically on a

special paper (Fig. 7) no t onl y the first arrivals bu t

T

i

m

e

,

.

m

s

e

c

o

o o

o

= L y ,

h:rr-y

V ^ m = i £'; £ :-Z ^

— -J '..; '■>,.rl'_ /,.■■■ j;- :v.^__ f— • . ■■ X lf -■' ~.T "'•— - '. ".— -■ ; iw -. . ■ 1 ...^

■ ' I ‘ ■ ■■■—■v ■ - .-I. '• .1 i ■■!■■■ i —»■■■■ ■ n ■■■ ... ~ -- ■J

— — -- V S— \ .- . , . Vi. ' •- -- - - — i

-“T1* i IIHZ.'?* i. ■ i_-?— . .-* . \ —>- ' . . >-.r ....

~rr‘- . ' 1 f .—i v ' - — r~.— r r r— -*z--- !-*— rrr*r— - ■■—■■ ■■■ J

■ - v .;.--- . - • •

~ ---7,___ ..., • ... , '______ ______

•’’T *..

.

- v J". =S=±=±=

A

it— ;=y rr.' iz t ~T": ...—:— ~

- ~

-ti—

-_L_

‘.j.’ 1 r

Tf-=-1--- ^---r- r

gg' 'x

-■•■r ya -■ ■ .i;, •, •..,,. —'.2.-.• ,■ :■ £~

^■r . . . ■ > ■ «■' ■ ■'• — ■ ■■!■■•■ ■ . . •‘..1.1: 7 - ■■■ ■ ’ ■ v l r- v..» ; ~'m ■

Zu5ZZ— ZZ

* ■ y >■v?

K 7*.” : . y"' . — ... ", ■ ■' . . . ' 1 . ■ "

■ " " 1 .... , ' ' i ~ i —

3^05 6.1

Distance, m

V 1_ 9.1^

7* Typical seismic record from the F S - 3 seismograph

also any subsequent arrivals that come to its two

geo-phones, thereby yielding more i n f o r m a t i o n about the s u b ­

surface condition. A special c o rrelator admits to the

recorder only those events which are coincident in b o t h

Seophones to decrease spurious "noise" events.

The source of energy for both instruments is a

sledge hammer striking a m e t a l l i c plate.

3.2.ii F i e l d Work

Sites w e r e selected such that the seismic velocities

could be correlated to specific sediment type and to re­

present w ide range of physical conditions (i.e. dry and

Wet s a m p l e s ) . Clay seismic velocities wer e m e a s u r e d nea r

construction sites or ditches. S a n d and/or gravel seismic

Velocities were m e a s u r e d n e a r "faces" of sand-gravel pits.

The gravel sites w ere u s u a l l y above w a t e r level. Some

sand sites were on the beach. Their seismic velocities

refer to w a t e r saturated beach sands (i.e. sites 17, 20,

22, 23).

W h e n the R-117B Timer was used, the geophone wa s

Placed o n the survey line. Whe n the FS-3 Seismograph was

used, the two geophones w ere placed symmetrically about

the survey line. Both instruments are shown in Appendix

VII.

The starting distance X was 0.6m (2 ft.). It was i n ­

creased b y increments of 0.6m up to 5m. Distances up to

1 0m were occ a s i o n a l l y used.

3.3 D a t a - S t a t i s t i c s

The s e i s m i c v e l o c i t i e s of the three groups (Table 4)

wer e a n a l y z e d s t a t i s t i c a l l y u s i n g the B M D P 3 D c o m p u t e r p r o ­

gram (Pu and Douglas, 1977). It p r o v i d e s m e a n and d e v i a t i o n

statistics (Table 5) as w e l l as g r o u p c o r r e l a t i o n s t a t i s t i c s

(Table 6 ). The g r o u p c o r r e l a t i o n s are m a d e by u s i n g the

"Student's t-test" w h i c h p r o v i d e s the t-statistic, and the

variance t e s t w h i c h p r o v i d e s the F-statistic. The t s t a

-tistic t ests the n ull h y p o t h e s i s that the m e a n s of two

groups are equal. In c o n t r a s t to c o n v e n t i o n a l t-tests

(Kennedy, 19 64) the a s s u m p t i o n m a d e here is that the

v a riances o f the two g r o u p s are n o t equal. In addition,

the d e g r e e s of f r e e d o m can b e n o n - i n t e g e r numbers

(Armitage, 1971). The F - s t a t i s t i c tests the n u l l h y p o ­

thesis that the v a r i a n c e s of two g r o u p s are equal. The

h i s t o g r a m s for the seis m i c v e l o c i t i e s of the three g r o u p s

are shown in Fig. 8 . A l t h o u g h the d i s t r i b u t i o n s of the

seismic v e l o c i t i e s d e p a r t fro m a n o r m a l d i s t r i b u t i o n the

t-test can be a p p l i e d for the c o m p a r i s o n of the three

groups b e c a u s e for all b u t small samples "the p - v a l u e s for

the t - t e s t are n o t g r e a t l y a f f e c t e d b y m o d e r a t e d e p a r t u r e s

from n o r m a l i t y " (Armitage, 1971).

Three p o s s i b l e p a i r s w e r e c o m p a r e d in this study,

n a m e l y G R A V E L v e r s u s SAND, G R A V E L ve r s u s CLAY and SAND

versus CLAY. The f o l l o w i n g c o n c l u s i o n s can be drawn

b a s e d on the c o m p u t e d statistics.

R

ep

rod

uc

ed

w

ith

pe

rm

is

s

io

n

of

th

e

co

py

ri

gh

t

o

w

ne

r.

Fu

rthe

r

re

production

p

ro

h

ib

ite

d

w

it

ho

ut

p

e

rm

is

s

io

n

.

CLAY

600 300

SAND

300 _{600 750 900 ' 1725 2100}

0 C cl) ?

01

0)

U A

0 GRAVEL

300 ^ 5 0

Velocity , m/sec

Fig. 8. Frequency distribution of the seismic velocities in the three groups GRAVEL,

1. The SAND g r o u p of samples shows the h i g h e s t m ean

V e l o c i t y b u t it also has the h i g h e s t s t a ndard deviation.

2. There is a v e r y small d i f f e r e n c e b e t w e e n the m e a n

v e locities of the G R A V E L a n d C LAY groups. The i n t e r e s t i n g

Point is that, statistically, the G R A V E L veloc i t i e s are

slightly h i g h e r than the CLAY velocities.

3. The t - s t a t i s t i c for the G R A V E L - S A N D p a i r is -1.9 8.

F°r 16.4 degrees of freedom, the c o r r e s p o n d i n g significance

level is 0.065 o r 6.5%. T h e r e f o r e the h y p o t h e s i s that the

m ean v e l o c i t i e s of the G R A V E L and S A N D groups are equal is

r e j e c t e d at the 9 3.5% c o nfidence level. Thus the seismic

Velocities of the SAND g r o u p are s t a t i s t i c a l l y d i f f e r e n t

from those of the G R A V E L group.

4. The t - s t a t i s t i c for the G R A V E L - C L A Y p air is 0.62.

por 23.8 degrees of f r e e d o m the c o r r e s p o n d i n g s i g n i ficance

level is 0.542 or 54.2%. This m e a n s tha t w e can rej e c t

fhe h y p o t h e s i s that the m e a n v e l o c i t y o f the two groups

a re equal at the 45.8% conf i d e n c e level a n d a c c e p t that

fheir m e a n v e l o c i t i e s are the same a t the 54.2% confidence

level. Th e r e f o r e the seismic v e l o c i t i e s of the GRAVEL

group are n o t s i g n i f i c a n t l y d i f f e r e n t f r o m those of the

CLAY group.

5. The t - s t a t i s t i c for the S A N D - C L A Y p a i r is 2.1.

For 18 degrees of f r e e d o m the c o r r e s p o n d i n g s i g n i ficance

level is 0.051 o r 5.1%. This, again suggests that the

m e a n v e l o c i t i e s of the S A N D and CLAY groups are

cally different at the 9 4.9% confidence level.

6 . The F-statistic gives similar results to those

from the T-test i.e. the CLAY and GRAVEL groups are simi­

lar in that they have relatively small standard d e v i a ­

tions whereas the SAND group differs from them in that it

has a relatively large standard deviation.

In summary the GRAVEL and SAND pair and the SAND and

CLAY pair have seismic velocities significantly different

while the GRAVEL and CLAY pair does not.

The exploration mean i n g of these statistical results

will be discussed in Chapter 5.

29

G R A V E L S A N D C L A Y

Site _{Velocity Site Velocity} Site Velocity

# (m/sec) _# (m/sec) # (m/sec)

1 _{365.8 16 1764.5 33 277.1}

2 _{34-3.2 17 2133.6 34- 641.6}

3 312.4 18 391.7 35 234 0 4

4 _{281.3 19 853.4- 36 268.2}

5 4-35.2 20 365.8 37 329.9

6 _{34-8.1 21 320.6 38 218.8}

7 _{4-57.2 22} 14-63.0 39 328.0

8 _4-87.7

23 54-8.6 40 228.9

9 _{4-35-2 24-} 381.0 41 391.4

10 _4-26.7

25 369.4- 42 304.8

11 _{335.3 26 270.7 4-3} 484.3

12 _{370.0 27 304.8 44 522.4}

13 4-74-.0 28 217.6 45 406.3

14- _{4-06.3 29}

731.5 46 735.5

15 365.8 30 426.7 4-7 232.2

31 304.8 48 361.8

32 461.8 49 341.4

•

50 290.2

Table _{4-. Seismic velocities for GRAVEI1, S A N D and CLAY in}

E s s e x _{C o u n t y .}

Velocity in m/sec.

GRAVEL SAND CLAY

•

J'-LAN _389.6

665.3 366.2

STANDARD DEVIATION 61.6 571.2

14-5.4-^t a nDARD e r r o r _16.2

138 ;5 34-.3

fr'-AxiLUK

4-87.2 2133-6 735-5

k'lNlNUjy!

281.3 217.6 218.8

Table 5 . Mean and deviation statistics for velocity for the

GRAVEL, SAND and CLAY groups.

GRAVEL v s SAND GRAVEL vs CLAY _{SAND vs CLAY}

T

-1 • 98 _{0.62 2.1}

P »

O .065 _{0.54-2 0.051}

d .f . _16.A

23.8 18.0

F

85.92 _{5.57 15*4-2}

P

O .000 _{0.062 0.000}

8 .F.

16 , 14.

17 , 14- 16 , 17

kle 6. Group correlation statistics for velocity.! is the

eParate statistic.P is the two-tail significance level.D.F.

the degrees of freedom and F is the F-statistic.

C H A P T E R I V

ELECTRICAL RESISTIVITY METHOD

4•1 Introduction

Electrical prospecting uses measurements of the elec­

trical properties of rocks to study the structure and com­

position of those layers which are sufficiently shallow to

ke exploited by man. Electrical prospecting was used as

early as 1720 by Gray-Wheeler (Jakosky, 1955). It makes

use of three fundamental properties of rocks: i) the re­

sistivity, ii) the electrochemical activity with respect

to electrolytes in the ground, and iii) the dielectric

constant.

Electrical resistivity measurements were used in this

study. The theory and results are presented in this

chapter.

4*2 Previous Work

The electrical resistivity method has been used suc­

cessfully in delineating sand and gravel deposits in the

past because they have very different resistivities than

clays, it works because "mostburied gravel and sands are

covered and surrounded by clay, ground moraine and flood

silt" (Kurtenacker, 19 34).

Kurtenacker (1934) has described briefly the use of

the resistivity method for reconnaissance and detailed

quarry surveys. In a more detailed paper, Moore (1944)