(a)
//
Driftless area
9
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'
"1-.
9
,,
' i .
i i l .i i
!i i i i !i i !i ;i i i i i !:i !i i i i :i
I
Climate change in glacial and periglacial regions
625
(b) w
~
Prominent moraines I ~
~
Drift
~"
~
Illinoian and older drifts
Lake Michigan
,': :..:'..;..'~:::.::
.' .~' .->~' .' ::.: :. :':.: :.'.. >:
:.' .'.'.
() "'..'.':"':'." ". " "'" 50" ;:.'" ': :'.'. :',' :100miies
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0 ". ..... .'..." 100km :.'.''.'.': ..
E
0"
0O.
O- 300
-250 ~"
200 []
150
Figure 24.7. Glacial deposits at the southern end of Lake Michigan. (a) At least four lobes in the front of
the Laurentide ice sheet have formed this configuration (Frye and Willman, 1973))9 (b) Profile across some
till sheets in northern Illinois (Frye and Willman, 1973; Wickham and Johnson, 1981, in Chorley et al.
(1984), Figure 1999