Great Lake Basins of the St. Lawrence. 253 
close of the era of the coal measures, generally under water, 
and unless Michigan has been the subject of extreme denu- 
dation, those portions of the State which surround the coal 
measures were dry land when these measures were de- 
posited. Since that period the State has been entirely above 
water, if we except any depression during quaternary 
times. Whatever the oscillations have been at different 
periods, the fact remains that the State is now in consider- 
able sections elevated between one thousand and two thou- 
sand feet above the sea, the areas between the central and 
northern portions of the State forming the highest levels. 
In the country on the immediate west side of Lake Michi- 
gan, the land has, with the same exception, been above 
water since about the period of the Niagara limestones and 
shales, and is now there, in many sections, also between one 
and two thousand feet above the sea. In the Ontario penin- 
ssula, on the east side of Lake Huron, there is an elevation 
reaching on the anticlinal at the Niagara escarpment as 
high as seventeen hundred feet. There is, however, good 
evidence, as will be shown farther on, that at some former 
time there have been certain marked disturbances in the 
general level of the Michigan, Krie, Huron and Ontario 
areas, operating probably simultaneously, and that these 
disturbances had much to do with the more general defining 
of the contours of these lakes. 
In following the history of the Great Lakes, the physical 
features of the lake bottoms afford some interesting chapters. 
The soundings undertaken by Cols. Meade, Comstock, and 
other engineers of the United States War Department, and 
those of Capt. Bayfield and Commander Bolton of the Cana- 
dian Marine Service, enable us to form some important con- 
clusions, especially when taken in connection with the physi- 
cal and geological features of the coasts of the lakes. That 
the lakes have to even a moderate extent a glacial origin does 
not appear to be borne out by the facts which these sound- 
ings reveal, however much icebergs and glaciers have con- 
tributed their quota of results to the outlines of some 
portions of the coasts and to the character and disposition 
of the material upon these coasts and upon the lake bottoms, 
