The Geology of Cincinnati. 51 
Within the past few years the researches of glacialists have 
shown that the present drainage system of the northern half 
of the Ohio drainage basin is very different from what it was 
before the advent of the Ice Age. The earlier drainage was 
COLS 
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ANCIENT CHANNELS --~~~ ! pee 
ARROWS POINT WIT! | Ag 
PRE-GLACIAL LOW. , i 
| Ze é 
| | HAMILTON Ba 
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| Ped mak \ mt 
x y/ = , ol af 
IM LAS fe =e 
if ye: us a\ 
t 
A Ids se r< Q <r, 
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4 
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LAWRENCEBURG oe Spd BX . 
MAYSVILLE 
J.M.M. Dol 9 FRANKFORT 
shaped by the sequence of geological events in paleozoic 
ages. This natural drainage, so to speak, was reformed by 
the advance of the ice sheet from the north, carrying with it 
a vast mass of debris from the lands corroded by it. The ice 
sheet and its debris, damming up ancient channels, backed 
the rivers up into lakes until the latter, breaking over the 
lower parts or cols of the bounding ridges, fashioned for the 
rivers new channels. The pre-glacial drainage of southwest- 
ern Ohio has been specially investigated by Mr. Gerard 
Fowke.* He considers that a col extended from the high- 
*Bull. Sci. Lab. Denison Univ., XI, 1899, pp. I-10; Ohio State Acad. Sci., Special 
Papers, No. 3. 1900, pp. 68-75. 
ies) 
