Mineralogy and Geology. 267 
. On Old Water Courses ; by Dr. J. 8. Newserry.—(To the 
citations from the memoir of Dr. Newberry on Surface Geology 
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nd lo 
uced without a continental elevation of several hundr et. 
few examples will suffice to show on what evidence this assertion 
is based. 
Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario are 
basins excavated in undisturbed sedimentary rocks. Of these, 
Lake Michigan is 600 feet deep, with a surface level of 578 feet 
above tides; Lake Huron is 500 feet deep, with a surface level of 
574 feet; Lake Erie is 204 feet deep, with a surface level of 565 
feet; Lake Ontario is 450 feet deep, with a surface level of 234 
feet above the sea. ; 
n old, excayated, now-filled channel connects Lake Erie and 
Lake Huron. At Detroit the rock surface is 130 feet below the 
city. In the oil region of Bothwell, &c., from 50 to 200 feet of 
clay overlie the rock. What the greatest depth of this channel is, 
Is not known. 
An excavated trough runs south from Lake Michigan—filled 
with clay, sand, tree trunks, &c.—penetrated at Bloomington, I., 
to the depth of 230 feet. See : : 
e rock bottoms of the troughs of the Mississippi and Missouri, 
hear their junction or below, have never been reached ; but they 
are many feet, perhaps some hundreds, beneath the present 
stream-beds, 
The Ohio throughout its entire course runs in a valley which 
has been cut ieetan less than 150 feet below the.present river. 
yahoga enters Lake Erie at Cleveland, more than, 100 
: f its excavated trough. ihe Una- 
ape ceaipe ine into Lake Erie exhibit 
_ The bottom of the excavated nel in whi 
is situated, and the Salina salt-wells bored, is at least 414 og 4 
low the surface level of the lake and 4 feet below the sea leve 
(Geddes. Trans, New York State Agric : 
The old cabhies of the Genesee River at Portage, described by 
