83∞

30'

W83∞

30'

W

83∞

00'

W83∞

00'

W

82∞

30'

W

82∞

30'

W

82∞

00'

W

82∞

00'

W

81∞

30'

W

81∞

30'

W

81∞

00'

W

81∞

00'

W

80∞

30'

W

80∞

30'

W

80∞

00'

W

80∞

00'

W

79∞

30'

W

79∞

30'

W

79∞

00'

W

79∞

00'

W

41∞

30'

N41

∞ 3

0'N

42∞

00'

N42

∞ 0

0'N

42∞

30'

N42

∞ 3

0'N

43∞

00'

N43

∞ 0

0'N

LON

G P

OIN

T ES

CA

RPM

ENT

This

nor

th-f

acin

g es

carp

men

t is

surr

ound

ed b

y irr

egul

ar to

pogr

aphy

whi

ch h

as a

relie

f of 1

-5 m

eter

s an

d a

dom

inan

t N

E-SW

lin

eatio

n ru

nnin

g at

a d

iago

nal

to t

he e

scar

pmen

t.

Poss

ibly

, th

e es

carp

men

t lie

s al

ong

the

boun

dary

se

para

ting

gent

ly s

outh

war

d di

ppin

g, m

ore

resi

stan

t up

per

Dev

onia

n de

ltaic

san

ds a

nd s

ilts,

or a

n up

per

Dev

onia

n lim

esto

ne b

ed w

hich

is m

ore

resi

stan

t tha

n th

e m

arin

e sh

ales

to th

e no

rth.

Alte

rnat

ely,

the

esca

rpm

ent c

ould

hav

e be

en

form

ed a

long

a p

reex

istin

g fa

ult,

whi

ch h

ad ju

xtap

osed

mor

e re

sist

ant a

nd le

ss r

esis

tant

stra

ta.

The

esca

rpm

ent i

s pa

ralle

l to

the

infe

rred

dire

ctio

n of

flow

of g

laci

al ic

e ad

vanc

ing

dow

n th

e ax

is o

f the

lake

floo

r. L

ack

of la

rge-

scal

e irr

egul

ariti

es a

long

the

edge

of t

he e

scar

pmen

t pro

babl

y re

flect

s the

like

lihoo

d th

at in

the

subg

laci

al re

gim

e of

ero

sion

, an

y no

rthw

ard

proj

ectio

ns o

f the

resi

stan

t ero

ding

stra

ta w

ere

shea

red

off d

ue to

the

erod

ing

pow

er o

f the

ice.

BATH

YM

ETR

Y O

F LA

KE

ERIE

AN

D L

AK

E SA

INT

CLA

IR

Nau

tical

Cha

rting

Div

ision

Cana

dian

Hyd

rogr

aphi

c Se

rvic

eD

epar

tmen

t of F

isher

ies a

nd O

cean

sO

ttawa

, Can

ada

Nat

iona

l Geo

phys

ical

Dat

a Ce

nter

Nat

iona

l Env

ironm

enta

l Sat

ellit

e, D

ata,

and

Info

rmat

ion

Serv

ice

Nat

iona

l Oce

anic

and

Atm

osph

eric

Adm

inist

ratio

nBo

ulde

r, Co

lora

do

NATIONAL OCEANIC A

ND

AT

MO

SP

HE

RIC

A

DMINISTRATION

U.S. D

EPAR

TM

EN

T O

F C

OM

MERCE

Gre

at L

akes

Env

ironm

enta

l Res

earc

h La

bora

tory

Offi

ce o

f Oce

anic

and

Atm

osph

eric

Res

earc

hN

atio

nal O

cean

ic a

nd A

tmos

pher

ic A

dmin

istra

tion

Ann

Arbo

r, M

ichi

gan

THE

ISLA

ND

S A

REA

The

isla

nds

and

reef

s bo

rder

ing

and

lyin

g w

ithin

the

wes

tern

ba

sin

have

bed

rock

cor

es w

hich

are

ero

sion

al r

emna

nts

of t

he

mor

e re

sist

ant r

ock

stra

ta.

The

isla

nds a

nd re

efs o

ccur

mai

nly

in

two

north

-sou

th b

ands

, the

wes

tern

ban

d (B

ass I

slan

ds, C

ataw

ba

Isla

nd,

Mid

dle

and

East

Sis

ter

Isla

nds)

for

med

on

eros

iona

l re

mna

nts

of re

sist

ant u

pper

Silu

rian

dolo

mite

s of

the

Put-i

n-B

ay

and

Rai

sin

Riv

er F

orm

atio

ns, a

nd th

e ea

ster

n ba

nd (M

arbl

ehea

d Pe

nins

ula,

Kel

leys

Isl

and,

Pel

ee I

slan

d) f

orm

ed o

n er

osio

nal

rem

nant

s of

re

sist

ant

low

er

Dev

onia

n lim

esto

nes

of

the

Col

umbu

s Fo

rmat

ion.

Th

e na

tura

l cha

nnel

s w

hich

occ

ur in

the

stra

its b

etw

een

the

Bas

s Is

land

s an

d ad

jace

nt to

thes

e is

land

s to

th

e w

est

are

over

dee

pene

d an

d ha

ve e

rode

d/co

rrod

ed t

hrou

gh

the

limes

tone

and

dol

omite

bed

rock

. The

dee

pest

cha

nnel

dep

th

is t

he 1

9-m

eter

Sta

rve

Isla

nd D

eep

loca

ted

betw

een

the

sout

hern

- mos

t Bas

s Isl

and

and

Mar

bleh

ead

Peni

nsul

a.

POIN

T PE

LEE

RID

GE

Poin

t Pe

lee

Rid

ge i

nclu

d es

Poin

t Pe

lee

and

exte

nds

offs

hore

sou

th-s

outh

east

war

d fo

r a

dist

ance

of

abou

t 10

kilo

met

ers,

whe

re i

t en

ds a

brup

tly.

This

rid

ge h

as 6

-8 m

eter

s of

to

tal

relie

f an

d ex

tend

s up

to

dept

hs o

f le

ss

than

5 m

eter

s. P

revi

ous

inte

rpre

tatio

ns h

ave

pres

ente

d Po

int

Pele

e to

geth

er w

ith P

oint

Pe

lee

Rid

ge a

s m

orai

ne a

ssoc

iate

d w

ith t

he

Pele

e-Lo

rain

Rid

ge o

n w

hich

350

0 ye

ars

befo

re p

rese

nt-to

-rec

ent

sand

dep

osits

hav

e be

en c

once

ntra

ted.

Si

nce

3500

yea

rs b

efor

e pr

esen

t, th

e su

baer

ial

exte

nt o

f Po

int

Pele

e ha

s di

min

ishe

d as

a

cons

eque

nce

of

cont

inue

d ris

ing

wat

er le

vels

.

POIN

T PE

LEE

FAN

Exte

ndin

g to

the

east

of t

he P

oint

Pel

ee R

idge

is th

e Po

int P

elee

Fan

, a fa

n-sh

aped

de

lta-li

ke b

ody

of s

edim

ents

whi

ch c

rest

s at

11-

12 m

eter

s be

low

pre

sent

lake

leve

l.

This

fan

is re

cogn

izab

le d

own

slop

e to

a d

epth

of 1

8 m

and

it e

xten

ds a

s far

sout

h as

th

e Pe

lee-

Lora

in R

idge

. B

ecau

se o

f its

cre

stal

dep

th o

f 11

-12

met

ers,

we

belie

ve

that

this

fan

may

hav

e be

en p

rinci

pally

form

ed a

t the

tim

e w

hen

the

lake

leve

l was

ab

out 1

0-15

met

ers

low

er th

an a

t pre

sent

, prio

r to

depo

sitio

n of

the

shal

low

er 3

500

year

s bef

ore

pres

ent t

o pr

esen

t san

ds o

n th

e Po

int P

elee

Rid

ge.

If th

is fa

n is

in fa

ct a

re

lict s

hore

line

feat

ure,

it m

ay h

ave

been

form

ed b

y th

e D

etro

it R

iver

whe

n th

e Po

rt H

uron

out

let f

rom

Lak

e H

uron

was

firs

t ope

ned

up a

nd th

e ne

wly

for

med

Det

roit

Riv

er w

as e

rodi

ng it

s cha

nnel

and

brin

ging

a h

eavy

load

of s

edim

ent i

nto

Lake

Erie

.

LON

G P

OIN

T-ER

IE R

IDG

E

The

Long

Poi

nt- E

rie R

idge

is a

bro

ad (1

4-22

kilo

met

ers)

arc

uate

ridg

e of

5-1

0 m

eter

s ov

eral

l re

lief,

capp

ed b

y co

mpl

ex to

pogr

aphy

, ext

endi

ng u

pwar

d to

min

imum

dep

ths

of 1

0-15

met

ers,

and

exte

ndin

g ac

ross

the

lake

floo

r fro

m n

ear t

he in

shor

e en

d of

the

Long

Poi

nt S

pit,

alm

ost t

o th

e Pr

esqu

e Is

le S

pit a

t Erie

, PA

. Thi

s fe

atur

e ha

s be

en in

terp

rete

d as

an

end

mor

aine

form

ed

durin

g th

e la

st m

ajor

re-

adva

nce

of g

laci

al ic

e in

to th

e Ea

ster

n Er

ie B

asin

. O

vera

ll sh

ape

of

the

East

ern

Erie

Bas

in, a

nd th

e ar

cuat

e sh

ape

and

topo

grap

hy o

f the

Lon

g Po

int-E

rie R

idge

, as

seen

in th

is n

ew b

athy

met

ry, s

treng

then

s the

inte

rpre

tatio

n th

at th

is fe

atur

e is

an

end

mor

aine

.

PEN

NSY

LVA

NIA

CH

AN

NEL

A ri

dge

exte

ndin

g w

estw

ard

alon

g th

e no

rth w

all o

f the

Pen

nsyl

vani

a C

hann

el su

gges

ts

a “n

atur

al le

vee”

in w

hich

sed

imen

ts e

rode

d fr

om th

e so

uthe

rn e

nd o

f the

Lon

g Po

int-

Erie

Rid

ge a

re c

arrie

d w

estw

ard

and

depo

site

d as

ove

rban

k de

posi

ts.

This

cha

nnel

is

the

loca

tion

of st

rong

retu

r n fl

ow fr

om th

e Ea

ster

n Er

ie B

asin

to th

e C

entra

l Erie

Bas

in,

whi

ch i

s se

t up

dur

ing

and

follo

win

g pe

riods

of

stro

ng f

ront

al w

inds

blo

win

g fr

om

wes

t to

east

long

itudi

nally

dow

n th

e le

ngth

of t

he la

ke s

urfa

ce.

Such

win

ds tr

ansp

ort

surf

ace

wat

er e

astw

ard,

rai

sing

lak

e le

vels

in

east

ern

Lake

Erie

and

req

uirin

g a

com

pens

atin

g w

estw

ard

flow

at

dept

h on

ce e

quili

briu

m i

s re

ache

d, o

r fo

llow

ing

rela

xatio

n of

the

stro

ng w

inds

. Th

is p

atte

rn o

f wat

er fl

ow o

ccur

s at p

rese

nt, b

ut it

may

ha

ve b

een

stro

nger

whe

n la

ke le

vels

wer

e lo

wer

.

LON

G P

OIN

T SP

IT

This

is

one

of t

he m

ost

prom

inen

t to

pogr

aphi

c fe

atur

es i

n La

ke E

rie,

exte

ndin

g ab

out

35

kilo

met

ers e

ast-s

outh

east

war

d fr

om th

e O

ntar

io sh

ore

out i

nto

the

East

ern

Erie

Bas

in. T

he sp

it is

a

late

Hol

ocen

e to

rec

ent d

epos

ition

al f

eatu

re c

onst

ruct

ed o

f sa

nd e

rode

d fr

om th

e O

ntar

io s

hore

cl

iffs

to th

e w

est a

nd b

roug

ht e

astw

ard

and

depo

site

d by

long

sho

re d

rift.

Ste

ep s

lope

s an

d 55

m

eter

s of

relie

f, th

e hi

ghes

t lak

e flo

or re

lief i

n La

ke E

rie, s

epar

ate

the

Spit

from

the

floor

of t

he

East

ern

Erie

Bas

in, d

irect

phy

sica

l evi

denc

e of

its r

ecen

t dep

ositi

onal

orig

in.

LAK

E SA

INT

CLA

IR

The

floor

of

Lake

Sai

nt C

lair

is v

ery

shal

low,

with

the

deep

est p

oint

lyin

g ju

st i

n ex

cess

of

6 m

eter

s. D

eep

wat

er s

ea l

anes

are

the

refo

re d

redg

ed

chan

nels

acr

oss

the

exte

nt o

f th

e La

ke.

Mic

roto

pogr

aphy

for

med

by

dum

ping

of

dred

ge s

poils

is p

rese

nt o

n ei

ther

sid

e of

the

dred

ged

sea

lane

ch

anne

l. O

ther

sm

all-s

cale

top

ogra

phy,

inc

ludi

ng a

nor

th-s

outh

rid

ge

exte

ndin

g no

rthw

ard

from

the

sout

h sh

ore,

may

be

anth

ropo

geni

c in

orig

in.

The

delta

of t

he S

aint

Cla

ir R

iver

is th

e do

min

ant f

eatu

re o

f the

Lak

e. T

his

plat

form

of d

elta

ic d

epos

its h

as b

een

built

out

into

the

Lake

, the

out

er e

dge

of w

hich

is b

ound

ed b

y fo

rese

t slo

pes

exte

ndin

g do

wnw

ard

from

pla

tform

de

pths

of l

ess t

han

one

met

er to

mor

e th

an 3

met

ers d

epth

.

CLE

AR

CR

EEK

RID

GE

A s

mal

l, na

rrow

arc

uate

rid

ge h

avin

g a

few

met

ers

relie

f oc

curs

8-

15 k

ilom

eter

s w

est

of,

and

appr

oxim

atel

y pa

ralle

l to

, th

e Lo

ng

Poin

t-Erie

Rid

ge.

Thi

s rid

ge,

prob

ably

gla

cial

in

orig

in,

is

unus

ually

lin

ear

for

a to

pogr

aphi

c fe

atur

e.

It ex

tend

s so

uthw

ard

from

the

Ont

ario

coa

st a

cros

s m

ore

than

hal

f the

wid

th o

f the

Lak

e.

Alth

ough

its

exa

ct o

rigin

rem

ains

a m

yste

ry,

it ha

s so

me

of t

he

mor

phol

ogic

al c

hara

cter

istic

s of a

n es

ker.

PELE

E-LO

RA

IN R

IDG

E

The

Pele

e-Lo

rain

Rid

ge e

xten

ds s

outh

east

war

d fr

om P

elee

Isla

nd a

lmos

t to

the

Ohi

o sh

ore.

Pr

evio

usly

it w

as a

ssum

ed th

at th

is lo

w ri

dge

was

con

tinuo

us b

etw

een

Poin

t Pel

ee a

nd it

s so

uthe

rn te

rmin

us n

ear t

he O

hio

Shor

e. T

his

new

bat

hym

etry

sho

ws

clea

rly, h

owev

er, t

hat

the

Pele

e-Lo

rain

Rid

ge is

not

con

tinuo

us w

ith P

oint

Pel

ee, b

ut is

inst

ead

cont

inuo

us w

ith

Pele

e Is

land

, 20

kilo

met

ers

to t

he s

outh

wes

t! T

his

ridge

has

bee

n in

terp

rete

d as

an

end

mor

aine

pro

babl

y as

soci

ated

with

a r

e-ad

vanc

e of

the

retre

atin

g W

isco

nsin

Ice

She

et, a

nd

prob

ably

cor

rela

ting

with

the

prog

laci

al L

ake

Mau

mee

II.

EXPO

SED

BED

RO

CK

IN W

ESTE

RN

LA

KE

ERIE

Are

as o

f ex

pose

d be

droc

k, c

hara

cter

ized

by

a fin

e-sc

ale

topo

grap

hy, h

ave

been

id

entif

ied

off

the

sout

hern

sho

relin

e w

est

and

east

of

Verm

ilion

, an

d ea

st o

f Lo

rain

, Ohi

o.

Seve

ral l

edge

s ar

e cl

early

del

inea

ted;

as

man

y as

thre

e se

para

te

ledg

es o

ccur

in p

arts

of

bot h

are

as.

Thes

e le

dges

are

pre

sum

ably

the

eros

iona

l su

rfac

e ex

pres

sion

of s

tratif

icat

ion

or jo

intin

g in

the

unde

rlyin

g up

per D

evon

ian

shal

es. O

ther

are

as o

f ex

pose

d be

droc

k oc

cur

arou

nd th

e la

ke, e

spec

ially

alo

ng

the

shor

elin

e of

the

East

ern

Erie

Bas

in.

SOU

THER

N S

HO

RE

OF

EAST

ERN

BA

SIN

The

sout

hern

sho

re b

orde

ring

the

East

ern

Erie

B

asin

is st

raig

hter

than

the

north

ern

shor

e an

d is

re

lativ

ely

free

of c

oves

and

inle

ts.

Mid

dle

and

uppe

r D

evon

ian

mar

ine

shal

es a

nd t

errig

enou

s si

ltsto

nes

of t

he H

amilt

on,

Gen

esee

, So

nyea

, W

est

Falls

, Ja

va,

and

Can

adaw

ay G

roup

s, in

as

cend

ing

orde

r, cr

op o

ut a

long

the

shor

e. T

hese

D

evon

ian

stra

ta i

nter

sect

the

sho

re a

t a

low

an

gle

and

exte

nd w

estw

ard

bene

ath

the

Lake

.

Coop

erat

ive

Insti

tute

for L

imno

logy

an

d Ec

osys

tem

s Res

earc

hU

nive

rsity

of M

ichi

gan

Ann

Arbo

r, M

ichi

gan

C

ILER

CIR

ESC

IRES

Coop

erat

ive

Insti

tute

for R

esea

rch

in E

nviro

nmen

tal S

cien

ces

Uni

vers

ity o

f Col

orad

o Bo

ulde

r, Co

lora

do

Wor

ld D

ata

Cen

ter A

for M

arin

e G

eolo

gy a

nd G

eoph

ysic

s Rep

ort M

GG

-13

1998

Publ

ished

by

the

Nat

iona

l Geo

phys

ical

Dat

a C

ente

rC

ode

E/G

C3,

325

Bro

adw

ay, B

ould

er, C

O 8

0303

-332

8in

fo@

ngdc

.noa

a.go

vht

tp://

ww

w.ng

dc.n

oaa.

gov/

mgg

/gre

atla

kes/

grea

tlake

s.htm

l

NO

RTH

ERN

SH

OR

E O

F EA

STER

N E

RIE

BA

SIN

An

irreg

ular

sho

relin

e un

derla

in b

y re

lativ

ely

resi

stan

t be

droc

k, c

appe

d by

onl

y a

thin

man

tle o

f gl

acia

l drif

t, ch

arac

teri z

es th

e no

rther

n sh

ore

of th

e Ea

ster

n Er

ie B

asin

. B

edro

ck o

utcr

ops

occu

r at

seve

ral l

ocat

ions

alo

ng th

e sh

ore.

Th

e irr

egul

ariti

es o

f th

e sh

orel

ine

are

cont

inuo

us w

ith N

E-SW

tre

ndin

g rid

ges

and

valle

ys w

hich

ext

end

offs

hore

. Th

ese

ridge

s ar

e fo

rmed

in r

elat

ivel

y re

sist

ant

basa

l lim

esto

nes

of t

he D

evon

ian

(Boi

s B

lanc

and

Dun

dee

Lim

esto

nes

in O

ntar

io;

cont

inui

ng

east

war

d as

Boi

s Bla

nc a

nd O

nond

aga

Lim

esto

nes i

n N

ew Y

ork

Stat

e).

Revi

ewer

s:J.

P. C

OA

KLE

Y, N

atio

nal W

ater

Res

earc

h In

stitu

te,

Burl

ingt

on O

nt.,

L7R

4A6

C. E

. HER

DEN

DO

RF,

Dep

artm

ent o

f Geo

logi

cal S

cien

ces,

The

Ohi

o St

ate

Uni

vers

ity,

Col

umbu

s OH

, 432

10

Proj

ect C

oord

inat

ors:

T. L

. HO

LCO

MBE

, NO

AA

Nat

iona

l Geo

phys

ical

Dat

a C

ente

r, B

ould

er C

O, 8

0303

D. F

. REI

D, N

OA

A G

reat

Lak

es E

nvir

onm

enta

l Res

earc

h La

bora

tory

, A

nn A

rbor

MI,

4810

5

Bath

ymet

ric C

ompi

latio

n:L.

A. T

AYLO

R, N

OA

A N

atio

nal G

eoph

ysic

al D

ata

Cen

ter,

Bou

lder

CO

, 803

03P.

VIN

CEN

T, C

oope

rativ

e In

stitu

te fo

r Lim

nolo

gy a

nd E

cosy

stem

s Res

earc

h, U

nive

rsity

of M

ichi

gan,

Ann

Arb

or M

I, 48

105

J. S

. WA

RR

EN, C

anad

ian

Hyd

rogr

aphi

c Se

rvic

e,

Imag

ery:

G. J

. SC

HW

AR

TZ, C

oope

rativ

e In

stitu

te fo

r Res

earc

h in

Env

iron

men

tal S

cien

ces,

Uni

vers

ity o

f Col

orad

o, B

ould

er C

O, 8

0309

L. A

. TAY

LOR

, NO

AA

Nat

iona

l Geo

phys

ical

Dat

a C

ente

r, B

ould

er C

O, 8

0303

015

3045

6460

Scal

e 1

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,000�

Tra

nsve

rse

Mer

cato

r Pro

ject

ion�

Con

tour

Inte

rval

: 1 m

eter�

Dep

th in

Met

ers

Thi

s map

is in

tend

ed to

show

lake

floo

r top

ogra

phy

and

is n

ot to

be

used

for n

avig

atio

n.

050

km

15

10

20

3

4

5

5

5 4

2 3

4

5

5

10

10

10

10

5

15

15

20

15

20

24

24

20

15

10

20

15

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20

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105

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15

15

10

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40

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60

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30

25 20

35

40

35

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20

15

10

5

5

10

10

20

15

20

40

We

ste

rn

Eri

e

Mau

mee

Bay

Ea

ste

rn E

rie

Ba

sin

Ce

ntr

al

Eri

e

Ba

sin

Ba

sin

Kelle

ys I.Pe

lee

Isla

nd

Poin

t Pe

lee Point P

elee Ridge

Po

int P

elee

Fan

San

dusk

y

B

ay

Pe l

ee -

Lora

in R

idge

Cana

da

Unite

d St

ates

Lora

in B

ank

Fa

i rp

or t

Ri d

ge

Con

neau

t

Ban

k

Pe

nn

sy

lva

nia

Ch

anne

l

C l e a r C r e e k Ri d

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L on g Poi nt -Er ie

Ridg e

Lo

ng

Po

int

Es

ca

rpm

en

t

Por

t M

aitla

nd

B

ank

Ga

sli

ne

R

idg

e

Pres

que

Isle

Spi

t

Van

Bure

n Po

int

Stur

geon

Poi

nt

Sai

nt C

lair

Del

ta

Poin

te A

ux

P

ins

Long

Poi

nt B

ay

Bu

ffa

loK

no

ll

Du

nki

rkB

an

k

Mar

bleh

ead

Peni

nsul

a

La

ke

Sa

int

Cla

ir

Du

nk

irk

Es

ca

rp

me

nt

Long

Poi

nt S

pit

B ass I s l ands

Wes

t Sis

ter I

.Mid

dle

Sist

er I.

Erieau R idge

Det

roit

Win

dsor

Tole

do

Sand

uskyLe

amin

gton

Lora

in

Verm

ilion

Erie

au

Cle

vela

nd

Asht

abul

a

Erie

Dun

kirk

Buffa

loFo

rt Er

iePo

rt C

olbo

urne

Port

Dov

er

Port

Burw

ell

Cleveland Ridge

83∞

30'

W

83∞

30'

W

83∞

00'

W

83∞

00'

W

82∞

30'

W

82∞

30'

W

82∞

00'

W

82∞

00'

W

81∞

30'

W

81∞

30'

W

81∞

00'

W

81∞

00'

W

80∞

30'

W

80∞

30'

W

80∞

00'

W

80∞

00'

W

79∞

30'

W

79∞

30'

W

79∞

00'

W

41∞

30'

N41

∞ 3

0'N

42∞

00'

N42

∞ 0

0'N

42∞

30'

N42

∞ 3

0'N

43∞

00'

N43

∞ 0

0'N

79∞

00'

W

Dat

a C

over

age

Can

adia

n H

ydro

grap

hic

Serv

ice

(CH

S)

surv

eys:

trac

k sp

acin

g <

500

m

CH

S su

rvey

s: t

rack

spa

cing

from

18

0 to

200

m

CH

S su

rvey

s: t

rack

spa

cing

< 2

50 m

CH

S su

rvey

s: t

rack

spa

cing

fro

m 1

5 to

60

m

Dig

ital U

.S. N

atio

nal O

cean

Ser

vice

(N

OS)

hyd

rogr

aphi

c so

undi

ngs

NO

S su

rvey

s: t

rack

spa

cing

< 5

00 m

Lake

floo

r fea

ture

nam

es h

ave

been

app

rove

d by

the

U.S

. Boa

rd o

n G

eogr

aphi

c N

ames

.

For F

urth

er R

eadi

ng:

LAR

SEN

, C

. E.

, 19

87.

Geo

logi

cal

hist

ory

of g

laci

al L

ake

Algo

nqui

n an

d th

e up

per

Gre

at L

akes

. U

.S.

Geo

logi

cal

Surv

ey B

ulle

tin 1

801-

35.

LEW

IS, C

. F. M

., A

ND

ERSO

N, T

. W.,

and

BER

TI, A

. A.,

1966

. G

eolo

gica

l a

nd p

alyn

olog

ical

stu

dies

of

early

Lak

e Er

ie d

epos

its. I

n Pr

ocee

ding

s of

the

9th

Con

fere

nce

on G

reat

La

kes

Rese

arch

, pp.

176

-191

. The

Uni

vers

ity o

f M

ichi

gan,

G

reat

Lak

es R

esea

rch

Div

isio

n Pu

blic

atio

n no

. 15.

LEW

IS,

T.

L.,

and

HER

DEN

DO

RF,

C

. E.

, 19

74.

Sedi

men

tolo

gy o

f th

e G

reat

Lak

es.

In L

imno

logy

of

Lake

s an

d Em

baym

ents

, ed

. A

. Pi

nsak

, G

reat

Lak

es F

ram

ewor

k St

udy,

Gre

at L

akes

Bas

in C

omm

issi

on.

MO

RTIM

ER,

C.

M.,

1987

. La

ke E

rie (

1929

-197

8):

Fifty

ye

ars

of

phys

ical

lim

nolo

gy.

Jour

nal

of

Gre

at

Lake

s Re

sear

ch 1

3(4)

:407

-435

.

SAY

LOR

, J. H

., an

d M

ILLE

R, G

. S.,

1987

. Stu

dies

of l

arge

-sc

ale

curr

ents

in L

ake

Erie

, 197

9-80

. Jou

rnal

of G

reat

Lak

es

Rese

arch

13(

4):4

87-5

14.

SLY,

P.

G,

1976

. La

ke E

rie a

nd i

ts b

asin

. Jo

urna

l of

the

Fi

sher

ies R

esea

rch

Boar

d of

Can

ada

33 (3

):355

-370

.

BO

LSEN

GA

, S. J

. , a

nd H

ERD

END

OR

F, C

. E.,

1993

. Lak

e Er

ie a

nd L

ake

St. C

lair

Han

dboo

k. W

ayne

Sta

te U

nive

rsity

Pr

ess,

Det

roit,

467

p.

CO

AK

LEY,

J. P

., 19

92. H

oloc

ene

trans

gres

sion

and

coa

stal

-la

ndfo

rm e

volu

tion

in n

orth

east

ern

Lake

Erie

, C

anad

a. I

n Q

uate

rnar

y C

oast

s of

the

Uni

ted

Stat

es:

Mar

ine

and

Lacu

stri

ne

Syst

ems,

pp.

415

-426

. SE

PM (

Soci

ety

for

Sedi

men

tary

Geo

logy

) Spe

cial

Pub

licat

ion

no. 4

8.

HER

DEN

DO

RF,

C

. E.

, 19

89.

Pale

ogeo

grap

hy

and

geom

orph

olog

y of

Lak

e Er

ie.

In L

ake

Erie

Est

uari

ne

Syst

ems:

Iss

ues,

Reso

urce

s, St

atus

, an

d M

anag

emen

t, pp

. 35

-70,

NO

AA

Est

uary

-of-

the-

Mon

th S

emin

ar S

erie

s no.

14.

HER

DEN

DO

RF,

C

. E.

, an

d B

AIL

EY,

M.

L.,

1989

. Ev

iden

ce f

or a

n ea

rly d

elta

of

the

Det

roit

Riv

er in

wes

tern

La

ke E

rie. O

hio

Jour

nal o

f Sci

ence

89:

16-2

2.

HER

DEN

DO

RF,

C.

E.,

and

BR

AID

ECH

, L.

L.,

1972

. Ph

ysic

al c

hara

cter

istic

s of

the

ree

f ar

ea o

f w

este

rn L

ake

Erie

. O

hio

Dep

artm

ent

of N

atur

al R

esou

rces

Div

isio

n of

G

eolo

gica

l Su

rvey

Rep

ort

of I

nves

tigat

ions

no.

82-

90,

map

s.

1)

A s

ucce

ssio

n of

Pal

eozo

ic (2

50-5

00 m

illio

n ye

ars

befo

re p

rese

nt) s

trata

wer

e de

posi

ted

over

the

reg

ion,

inc

ludi

ng t

he e

asily

ero

dibl

e D

evon

ian

(350

-400

mill

ion

year

s be

fore

pr

esen

t) sh

allo

w w

ater

mar

ine

shal

es a

nd c

arbo

nate

s int

o w

hich

the

Lake

Bas

in w

as e

rode

d.

2)��

An

elab

orat

e sy

stem

of d

rain

age

chan

nels

was

inci

sed

into

the

Pale

ozoi

c be

droc

k du

ring

post

-Pal

eozo

ic, p

re-g

laci

al ti

me

whe

n th

e re

gion

was

ele

vate

d ab

ove

sea

leve

l.

3) R

epea

ted

epis

odes

of g

laci

al e

rosi

on e

xcav

ated

the

lake

bas

in d

urin

g Pl

eist

ocen

e tim

e (0

-2

mill

ion

year

s bef

ore

pres

ent).

4) F

inal

retre

at o

f gla

cial

ice

from

the

area

abo

ut 1

3,00

0 ye

ars

befo

re p

rese

nt le

ft in

pla

ce a

to

pogr

aphi

c su

rfac

e fo

rmed

by

eros

ion

of b

edro

ck a

nd b

y de

posi

tion

of s

edim

ents

un

dern

eath

and

nea

r the

mar

gins

of t

he ic

e sh

eet.

5)

Lake

flo

or to

pogr

aphy

was

mod

ified

fol

low

ing

degl

acia

tion

by d

epos

ition

and

cur

rent

sc

ulpt

ing

of se

dim

ents

on

the

lake

floo

r. A

nthr

opog

enic

effe

cts o

f dre

dgin

g an

d m

inin

g al

so

cont

ribut

ed to

topo

grap

hic

mod

ifica

tion.

Lake

Evo

lutio

nBa

thym

etri

c C

ompi

latio

n

Con

tinui

ng c

oope

rativ

e ef

fort

betw

een

NO

AA

and

th

e C

anad

ian

Hyd

rogr

aphi

c Se

rvic

e ha

s re

sulte

d in

th

e co

mpl

etio

n of

this

bat

hym

etry

. Th

e ba

thym

etry

w

as

com

pile

d m

ostly

at

sc

ales

ra

ngin

g fr

om

1:2,

500

to 1

:100

,000

, us

ing

the

entir

e hi

stor

ic

hydr

ogra

phic

sou

ndin

g da

ta b

ase

from

the

Uni

ted

Stat

es a

nd C

anad

a.

The

cont

ours

hav

e be

en

regi

ster

ed t

o th

e N

OA

A n

omin

al s

cale

1:8

0,00

0 d i

gita

l vec

tor s

hore

line.

In s

ome

area

s, su

ch a

s al

ong

the

Can

adia

n sh

ore,

gr

eate

r de

tail

is s

een

in th

e co

ntou

rs th

an in

oth

er

area

s. T

his

is a

nat

ural

con

sequ

ence

of d

iffer

ence

s in

the

track

line

spac

ing

of th

e ba

thym

etric

sur

veys

us

ed in

the

com

pila

tion.

The

bat

hym

etry

has

bee

n ra

ster

sca

nned

and

vec

toriz

ed,

and

will

soo

n be

av

aila

ble

in th

e fo

rm o

f dig

ital d

ata

and

imag

ery.

83∞ 30'W 83∞ 30'W

83∞ 00'W 83∞ 00'W

82∞ 30'W

82∞ 30'W

82∞ 00'W

82∞ 00'W

81∞ 30'W

81∞ 30'W

81∞ 00'W

81∞ 00'W

80∞ 30'W

80∞ 30'W

80∞ 00'W

80∞ 00'W

79∞ 30'W

79∞ 30'W

79∞ 00'W

79∞ 00'W

41∞ 30'N41∞ 30'N

42∞ 00'N42∞ 00'N

42∞ 30'N42∞ 30'N

43∞ 00'N43∞ 00'N

LON

G PO

INT ESC

AR

PMEN

T

This north-facing escarpment is surrounded by irregular topography w

hich has a relief of 1-5 meters and a dom

inant N

E-SW lineation running at a diagonal to the escarpm

ent. Possibly, the escarpment lies along the boundary

separating gently southward dipping, m

ore resistant upper Devonian deltaic sands and silts, or an upper D

evonian lim

estone bed which is m

ore resistant than the marine shales to the north. A

lternately, the escarpment could have been

formed along a preexisting fault, w

hich had juxtaposed more resistant and less resistant strata. The escarpm

ent is parallel to the inferred direction of flow

of glacial ice advancing down the axis of the lake floor. Lack of large-scale

irregularities along the edge of the escarpment probably reflects the likelihood that in the subglacial regim

e of erosion, any northw

ard projections of the resistant eroding strata were sheared off due to the eroding pow

er of the ice.

BATHY

METR

Y O

F LAK

E ERIE A

ND

LAK

E SAIN

T CLA

IR

Nautical Charting D

ivisionCanadian H

ydrographic ServiceD

epartment of Fisheries and O

ceansO

ttawa, Canada

National G

eophysical Data Center

National Environm

ental Satellite, Data, and Inform

ation ServiceN

ational Oceanic and Atm

ospheric Administration

Boulder, Colorado

NATIONAL OCEANIC A

ND

AT

MO

SP

HE

RIC ADMINISTRATION

U.S. DEPAR

TM

EN

T O

F C

OM

MERCE

Great Lakes Environm

ental Research LaboratoryO

ffice of Oceanic and Atm

ospheric ResearchN

ational Oceanic and Atm

ospheric Administration

Ann Arbor, Michigan

THE ISLA

ND

S AR

EA

The islands and reefs bordering and lying within the w

estern basin have bedrock cores w

hich are erosional remnants of the

more resistant rock strata. The islands and reefs occur m

ainly in tw

o north-south bands, the western band (B

ass Islands, Cataw

ba Island, M

iddle and East Sister Islands) formed on erosional

remnants of resistant upper Silurian dolom

ites of the Put-in-Bay

and Raisin R

iver Formations, and the eastern band (M

arblehead Peninsula, K

elleys Island, Pelee Island) formed on erosional

remnants

of resistant

lower

Devonian

limestones

of the

Colum

bus Formation. The natural channels w

hich occur in the straits betw

een the Bass Islands and adjacent to these islands to

the west are over deepened and have eroded/corroded through

the limestone and dolom

ite bedrock. The deepest channel depth is the 19-m

eter Starve Island Deep located betw

een the southern- m

ost Bass Island and M

arblehead Peninsula.

POIN

T PELEE RID

GE

Point Pelee Ridge includes Point Pelee and

extends offshore south-southeastward for a

distance of about 10 kilometers, w

here it ends abruptly. This ridge has 6-8 m

eters of total relief and extends up to depths of less than 5 m

eters. Previous interpretations have presented Point Pelee together w

ith Point Pelee R

idge as moraine associated w

ith the Pelee-Lorain R

idge on which 3500 years

before present-to-recent sand deposits have been concentrated. Since 3500 years before present, the subaerial extent of Point Pelee has

diminished

as a

consequence of

continued rising water levels.

POIN

T PELEE FAN

Extending to the east of the Point Pelee Ridge is the Point Pelee Fan, a fan-shaped

delta-like body of sediments w

hich crests at 11-12 meters below

present lake level. This fan is recognizable dow

n slope to a depth of 18 m and it extends as far south as

the Pelee-Lorain Ridge. B

ecause of its crestal depth of 11-12 meters, w

e believe that this fan m

ay have been principally formed at the tim

e when the lake level w

as about 10-15 m

eters lower than at present, prior to deposition of the shallow

er 3500 years before present to present sands on the Point Pelee R

idge. If this fan is in fact a relict shoreline feature, it m

ay have been formed by the D

etroit River w

hen the Port H

uron outlet from Lake H

uron was first opened up and the new

ly formed D

etroit R

iver was eroding its channel and bringing a heavy load of sedim

ent into Lake Erie.

LON

G PO

INT-ER

IE RID

GE

The Long Point- Erie Ridge is a broad (14-22 kilom

eters) arcuate ridge of 5-10 meters overall

relief, capped by complex topography, extending upw

ard to minim

um depths of 10-15 m

eters, and extending across the lake floor from

near the inshore end of the Long Point Spit, almost to

the Presque Isle Spit at Erie, PA. This feature has been interpreted as an end m

oraine formed

during the last major re-advance of glacial ice into the Eastern Erie B

asin. Overall shape of

the Eastern Erie Basin, and the arcuate shape and topography of the Long Point-Erie R

idge, as seen in this new

bathymetry, strengthens the interpretation that this feature is an end m

oraine.

PENN

SYLVA

NIA C

HA

NN

EL

A ridge extending w

estward along the north w

all of the Pennsylvania Channel suggests

a “natural levee” in which sedim

ents eroded from the southern end of the Long Point-

Erie Ridge are carried w

estward and deposited as overbank deposits. This channel is

the location of strong return flow from

the Eastern Erie Basin to the C

entral Erie Basin,

which is set up during and follow

ing periods of strong frontal winds blow

ing from

west to east longitudinally dow

n the length of the lake surface. Such winds transport

surface water eastw

ard, raising lake levels in eastern Lake Erie and requiring a com

pensating westw

ard flow at depth once equilibrium

is reached, or following

relaxation of the strong winds. This pattern of w

ater flow occurs at present, but it m

ay have been stronger w

hen lake levels were low

er.

LON

G PO

INT SPIT

This is one of the most prom

inent topographic features in Lake Erie, extending about 35 kilom

eters east-southeastward from

the Ontario shore out into the Eastern Erie B

asin. The spit is a late H

olocene to recent depositional feature constructed of sand eroded from the O

ntario shore cliffs to the w

est and brought eastward and deposited by long shore drift. Steep slopes and 55

meters of relief, the highest lake floor relief in Lake Erie, separate the Spit from

the floor of the Eastern Erie B

asin, direct physical evidence of its recent depositional origin.

LAK

E SAIN

T CLA

IR

The floor of Lake Saint Clair is very shallow, w

ith the deepest point lying just in excess of 6 m

eters. Deep w

ater sea lanes are therefore dredged channels across the extent of the Lake. M

icrotopography formed by

dumping of dredge spoils is present on either side of the dredged sea lane

channel. Other sm

all-scale topography, including a north-south ridge extending northw

ard from the south shore, m

ay be anthropogenic in origin. The delta of the Saint C

lair River is the dom

inant feature of the Lake. This platform

of deltaic deposits has been built out into the Lake, the outer edge of w

hich is bounded by foreset slopes extending downw

ard from platform

depths of less than one m

eter to more than 3 m

eters depth.

CLEA

R C

REEK

RID

GE

A sm

all, narrow arcuate ridge having a few

meters relief occurs 8-

15 kilometers w

est of, and approximately parallel to, the Long

Point-Erie Ridge. This ridge, probably glacial in origin, is

unusually linear for a topographic feature. It extends southward

from the O

ntario coast across more than half the w

idth of the Lake. A

lthough its exact origin remains a m

ystery, it has some of the

morphological characteristics of an esker.

PELEE-LOR

AIN

RID

GE

The Pelee-Lorain Ridge extends southeastw

ard from Pelee Island alm

ost to the Ohio shore.

Previously it was assum

ed that this low ridge w

as continuous between Point Pelee and its

southern terminus near the O

hio Shore. This new bathym

etry shows clearly, how

ever, that the Pelee-Lorain R

idge is not continuous with Point Pelee, but is instead continuous w

ith Pelee Island, 20 kilom

eters to the southwest! This ridge has been interpreted as an end

moraine probably associated w

ith a re-advance of the retreating Wisconsin Ice Sheet, and

probably correlating with the proglacial Lake M

aumee II.

EXPO

SED BED

RO

CK

IN W

ESTERN

LAK

E ERIE

Areas of exposed bedrock, characterized by a fine-scale topography, have been

identified off the southern shoreline west and east of Verm

ilion, and east of Lorain, O

hio. Several ledges are clearly delineated; as many as three separate

ledges occur in parts of both areas. These ledges are presumably the erosional

surface expression of stratification or jointing in the underlying upper Devonian

shales. Other areas of exposed bedrock occur around the lake, especially along

the shoreline of the Eastern Erie Basin.

SOU

THER

N SH

OR

E OF EA

STERN

BASIN

The southern shore bordering the Eastern Erie B

asin is straighter than the northern shore and is relatively free of coves and inlets. M

iddle and upper D

evonian marine shales and terrigenous

siltstones of the Ham

ilton, Genesee, Sonyea,

West Falls, Java, and C

anadaway G

roups, in ascending order, crop out along the shore. These D

evonian strata intersect the shore at a low

angle and extend westw

ard beneath the Lake.

Cooperative Institute for Limnology

and Ecosystems Research

University of M

ichiganAnn Arbor, M

ichigan C

ILER

CIR

ESC

IRES

Cooperative Institute for Researchin Environm

ental SciencesU

niversity of Colorado Boulder, Colorado

World D

ata Center A for M

arine Geology and G

eophysics Report M

GG

-131998

Published by the National G

eophysical Data C

enterC

ode E/GC

3, 325 Broadw

ay, Boulder, C

O 80303-3328

info@ngdc.noaa.gov

http://ww

w.ngdc.noaa.gov/mgg/greatlakes/greatlakes.htm

l

NO

RTH

ERN

SHO

RE O

F EASTER

N ER

IE BASIN

An irregular shoreline underlain by relatively resistant bedrock, capped by only a thin m

antle of glacial drift, characterizes the northern shore of the Eastern Erie B

asin. Bedrock outcrops occur at

several locations along the shore. The irregularities of the shoreline are continuous with N

E-SW

trending ridges and valleys which extend offshore. These ridges are form

ed in relatively resistant basal lim

estones of the Devonian (B

ois Blanc and D

undee Limestones in O

ntario; continuing eastw

ard as Bois B

lanc and Onondaga Lim

estones in New

York State).

Reviewers:J. P. C

OA

KLEY, N

ational Water R

esearch Institute, Burlington Ont., L7R

4A6

C. E. H

ERD

END

OR

F, Departm

ent of Geological Sciences, The O

hio State University, C

olumbus O

H, 43210

Project Coordinators:T. L. H

OLC

OM

BE, NO

AA N

ational Geophysical D

ata Center, Boulder C

O, 80303

D. F. R

EID, N

OA

A Great Lakes Environm

ental Research Laboratory, A

nn Arbor M

I, 48105

Bathymetric Com

pilation:L. A

. TAYLO

R, N

OA

A National G

eophysical Data C

enter, Boulder CO

, 80303P. V

INC

ENT, C

ooperative Institute for Limnology and Ecosystem

s Research, U

niversity of Michigan, A

nn Arbor M

I, 48105J. S. W

AR

REN

, Canadian H

ydrographic Service,

Imagery:

G. J. SC

HW

AR

TZ, Cooperative Institute for R

esearch in Environmental Sciences, U

niversity of Colorado, Boulder C

O, 80309

L. A. TAY

LOR

, NO

AA N

ational Geophysical D

ata Center, Boulder C

O, 80303

015

3045

6460

Scale 1:350,000� Transverse M

ercator Projection� Contour Interval: 1 m

eter�

Depth in M

eters

This map is intended to show

lake floor topography and is not to be used for navigation.

050

km

15

10

20

3

4

5

5

5 4

2 3

4

5

5

10

10

10

10

5

15

15

20

15

20

24

24

20

15

10

20

15

105

20

15

105

20

510

15

15

10

25 30

35

40

45

60

5550

45 40

35

3025

63

55

45

30

2520

35

40

35

2520

15

3025

20

10

20

15

10

5

5

10

10

20

15

20

40

We

ste

rn E

rie

Maum

ee B

ay

Ea

ste

rn E

rie

Ba

sin

Ce

ntra

l Erie

Ba

sin

Ba

sin

Kelleys I. PeleeIsland

Point Pelee

Point Pelee Ridge

Po

intP

elee

Fan

Sandusky B

ay

Pelee - Lorain Ridge

Canada

United States

Lorain Bank

Fa

irpo

rtR

idg

e

Conneaut

Bank

Pe

nn

sy

l va

ni a

Ch

an n e

l

Clear Creek Ridge

Long Point -Erie Ridge

Lo

ng

Po

i nt E

sc

ar p

me

nt

Port M

aitland B

ank

Ga

sl i n

e R

i dg

e

PresqueIsle Spit

Van Buren Point

Sturgeon Point

Saint C

lair D

elta

Pointe Aux Pins

Long Point Bay

Bu

ffalo

Kn

oll

Du

nkirk

Ba

nk

Marblehead Peninsula

La

ke

Sa

int C

lair

Du

nk

i r k E

sc

ar

pm

en

t

Long Point Spit

Bass Islands

West Sister I. M

iddle Sister I.

Erieau Ridge

Detroit

Windsor

Toledo

Sandusky

Leamington

Lorain

Vermilion

Erieau

Cleveland

Ashtabula

Erie

Dunkirk

BuffaloFort Erie

Port Colbourne

Port Dover

Port Burwell

Cleveland Ridge

83∞ 30'W

83∞ 30'W

83∞ 00'W

83∞ 00'W

82∞ 30'W

82∞ 30'W

82∞ 00'W

82∞ 00'W

81∞ 30'W

81∞ 30'W

81∞ 00'W

81∞ 00'W

80∞ 30'W

80∞ 30'W

80∞ 00'W

80∞ 00'W

79∞ 30'W

79∞ 30'W

79∞ 00'W

41∞ 30'N41∞ 30'N

42∞ 00'N42∞ 00'N

42∞ 30'N42∞ 30'N

43∞ 00'N43∞ 00'N

79∞ 00'W

Data C

overage

Canadian H

ydrographic Service (CH

S) surveys: track spacing < 500 m

CH

S surveys: track spacing from

180 to 200 m

CH

S surveys: track spacing < 250 m

CH

S surveys: track spacing from

15 to 60 m

Digital U

.S. National O

cean Service (N

OS) hydrographic soundings

NO

S surveys: track spacing < 500 m

Lake floor feature names have been approved by the U

.S. Board on Geographic N

ames.

For Further Reading:

LAR

SEN, C

. E., 1987. Geological history of glacial Lake

Algonquin and the upper Great Lakes. U

.S. Geological

Survey Bulletin 1801-35.

LEWIS, C

. F. M., A

ND

ERSO

N, T. W

., and BERTI, A

. A.,

1966. Geological and palynological studies of early Lake

Erie deposits. In Proceedings of the 9th Conference on G

reat Lakes Research, pp. 176-191. The U

niversity of Michigan,

Great Lakes R

esear ch Division Publication no. 15.

LEWIS,

T. L.,

and H

ERD

END

OR

F, C

. E.,

1974. Sedim

entology of the Great Lakes. In Lim

nology of Lakes and Em

bayments, ed. A

. Pinsak, Great Lakes Fram

ework

Study, Great Lakes B

asin Com

mission.

MO

RTIMER

, C. M

., 1987. Lake Erie (1929-1978): Fifty years

of physical

limnology.

Journal of

Great

Lakes Research 13(4):407-435.

SAYLO

R, J. H

., and MILLER

, G. S., 1987. Studies of large-

scale currents in Lake Erie, 1979-80. Journal of Great Lakes

Research 13(4):487-514. SLY, P. G

, 1976. Lake Erie and its basin. Journal of the Fisheries Research Board of C

anada 33 (3):355-370.

BO

LSENG

A, S. J. , and H

ERD

END

OR

F, C. E., 1993. Lake

Erie and Lake St. Clair H

andbook. Wayne State U

niversity Press, D

etroit, 467 p.

CO

AK

LEY, J. P., 1992. Holocene transgression and coastal-

landform evo lution in northeastern Lake Erie, C

anada. In Q

uaternary Coasts of the U

nited States: Marine and

Lacustrine System

s, pp. 415-426. SEPM (Society for

Sedimentary G

eology) Special Publication no. 48.

HER

DEN

DO

RF,

C.

E., 1989.

Paleogeography and

geomorphology of Lake Erie. In Lake Erie Estuarine

Systems: Issues, Resources, Status, and M

anagement, pp.

35-70, NO

AA

Estuary-of-the-Month Sem

inar Series no. 14 .

HER

DEN

DO

RF,

C.

E., and

BA

ILEY, M

. L.,

1989. Evidence for an early delta of the D

etroit River in w

estern Lake Erie. O

hio Journal of Science 89:16-22.

HER

DEN

DO

RF, C

. E., and BR

AID

ECH

, L. L., 1972. Physical characteristics of the reef area of w

estern Lake Erie. O

hio Departm

ent of Natural R

esources Division of

Geological Survey R

eport of Investigations no. 82-90, m

aps.

1) A succession of Paleozoic (250-500 m

illion years before present) strata were deposited

over the region, including the easily erodible Devonian (350-400 m

illion years before present) shallow

water m

arine shales and carbonates into which the Lake B

asin was eroded.

2)�� An elaborate system

of drainage channels was incised into the Paleozoic bedrock during

post-Paleozoic, pre-glacial time w

hen the region was elevated above sea level.

3) Repeated episodes of glacial erosion excavated the lake basin during Pleistocene tim

e (0-2 m

illion years before present).

4) Final retreat of glacial ice from the area about 13,000 years before present left in place a

topographic surface formed by erosion of bedrock and by deposition of sedim

ents underneath and near the m

argins of the ice sheet.

5) Lake floor topography was m

odified following deglaciation by deposition and current

sculpting of sediments on the lake floor. A

nthropogenic effects of dredging and mining also

contributed to topographic modification.

Lake EvolutionBathym

etric Com

pilation

Continuing cooperative effort betw

een NO

AA

and the C

anadian Hydrographic Service has resulted in

the completion of this bathym

etry. The bathymetry

was

compiled

mostly

at scales

ranging from

1:2,500 to 1:100,000, using the entire historic hydrographic sounding data base from

the United

States and Canada. The contours have been

registered to the NO

AA

nominal scale 1:80,000

digital vector shoreline. In som

e areas, such as along the Canadian shore,

greater detail is seen in the contours than in other areas. This is a natural consequence of differences in the trackline spacing of the bathym

etric surveys used in the com

pilation. The bathymetry has been

raster scanned and vectorized, and will soon be

available in the form of digital data and im

agery.