IT" I'ke American Geoloytsi. ^eptcinbor, i896 
now ijusses arouiul tlie south and west sides of the Laurentian 
lakes, extended instead during i\\\ the Tertiaiy era, and in the 
early C^uaternary u]> to the Ice Age, along the Allegheny 
mountain belt and directly onward northeasterly to the Adi- 
rondacks, turning thence northwesterly across the Ontario 
higiilands east of Georgian hay to the present hight of land 
nortli of lake Superior. The preglacial Laurentian river of 
Spencer, which he supposes to have received the drainage of 
tlie present Laurentian lakes area. api)ears to nie raore proba- 
lil}" to have been limited to head streams which are now rep- 
resented by lake Chanii)lain, the Ottawa river, and the 
Saguenay. We certainly owe much to Spencer for his valuable 
pioneer studies of the preglacial channels of connection be- 
tween the several Laurentian lake basins; but I believe that 
the grand topographic features of the region, with' our knowl- 
edge of the epeirogenic movements ending the Tertiary and 
bringing in the Quaternary era, should lead us to look for the 
Tertiary lower course of the river draining the area of the 
present Laurentian lakes along some route southerly from 
lake Michigan, rather than either easterly from lake Ontario 
along the Mohawk valley or northeasterly along the St. Law- 
rence valle}''. 
Since the elevation of the interior of our continent from its 
mediterranean Cretaceous sea, and since tlie ajiproximately 
contemporaneous uplift of the Jura-Cretaceous or Schooley 
l)eneplain, which had occupied the country eastAvard, so well 
studied by Davis, Wood, Hershey and others, vast denudation 
and broad and deep valley erosion have sculptured the Colo- 
rado plateaus and canon, have cut down the surface of the 
great western jilains hundreds and in part thousands of feet, 
have eroded the broad Appalachian valleys, and have chan- 
neled the fjords of Greenland (as is demonstrabh^ notably for 
the VVaigat passage setting off the island of Disco), besides 
probably also eroding the greater part of the straits, sounds, 
gulfs and bays of the Arctic archipehigo and the Hudson bay 
region. Amid sucli slu])endous subaerial erosion, tlie basins 
of the Laurentian lakes received essentially their present 
forms, but with continuous and free drainage, as I believe, 
toward tlie west and south. A great trunk stream Howing 
south along the bed of lake Michigan drew its chief trihuta 
