8. V. Wood, j an. — American ancl British Surface- Geology. 537 
(such, I suppose, as that which blocked out the sea from the lake- 
basin cluring the depression which gave rise to the marine clays of 
the Lower St. Lawrence), or by the cutting away of barriers of 
drift, or even, he adds, by the “ warping of the earth’s crust.” It 
does not appear that any of these terraces, though possessing great 
constancy of level, present such visible regularity as the well-known 
roads of Glenroy ; but if, as is the more probable, the shrinkage of 
the lake-basin was due to the removal of an ice-dam, their origin 
would seem to be identical with that to which the inclination of 
modern opinion refers these roads. 
A very interesting feature in the geology of the lake region 
consists in the buried channels now filled with and concealed by 
Drift. Some of these form the waste weirs just referred to, but 
they occur also at various lower levels, even to levels beneath those 
of the existing lakes ; so that if opened again great modifications 
would take place in the hydrographical conditions of the St. Law- 
rence basin ; and indeed Prof. Newberry ventures to assert that 
buried channels of communication exist between Lake Erie and 
Lake Ontario. If such exist, then, of course, Niagara could by 
their opening be laid dry, and he dwells on the praetical Service to 
which the various buried channels might be turned for engineering 
purposes. He also insists on the soundness of the rock-basin 
erosion theory as applied to the entire valley of the St. Lawrence. 
This valley he describes as having been prior to the Glacial period, 
and when the elevation of that part of the North American con- 
tinent was considerably greater than now, the valley of a river- 
system which flowed at much lower levels than at present ; and 
which, instead of reaching the Atlantic as it now does by way of 
the Gulf of St. Lawrence, flowed between the Adirondack and 
Appalachian mountains, in the line of one of these buried channels, 
passing through the trough of the Hudson River, and emptying 
into the Atlantic about eighty miles south-east of New York. At 
this time, according to the Professor, that part of the St. Lawrence 
valley which is now formed by the basins of Lakes Michigan and 
Superior formed no part of the river-system to which they now 
belong, but part of a separate river-system emptying itself into the 
Mississippi, the Straits of Mackinau not being then opened ; and it 
is to the erosive action of the glacier-ice, which during the Glacial 
period crept down from the Laurentian highlands of Canada, and 
filled these pre-existing valley Systems, that he attributes their 
excavation and conversion into the one great basin which now 
receives so large a part of the drainage of North America, and is 
referred to under the name of the lake-basin, or basin of the St. 
Lawrence. 
Assuming that my suggestions as to the period and mode of 
origin of the Ohio Eskers have some good foundation, I propose, 
subject to the qualifving observations applied to each case, to 
suggest certain synchronisms between the Glacial and post-Glacial 
phenomena of the St. Lawrence basin and those of Britain, according 
to the view of the English beds to which their study has led me. 
