ERIE PREGLACIAL OUTLET 231 



ually dissected the plateau into separated masses, such as those which 

 on subsequent submersion now form the island chain north of Lake 

 Huron. Similar preglacial features occur elsewhere now buried beneath 

 the mantle of drift. 



Concerning the preglacial Erie Outlet 

 At least three depressions below the Erie level cross the Niagara lime- 

 stone belt between it and Lake Ontario. These have been found by bor- 

 ings. The deepest of them is the Erigan Channel, situated 12 to 14 miles 

 west of Niagara Falls (A on map). This was the great preglacial out- 

 let of the upper valley. At its northern end may be observed one of the 

 deep indentations in the face of the Niagara escarpment; otherwise the 

 ancient valley is entirely concealed by drift for the remainder of the dis- 

 tance across the peninsula between the two lakes, but borings have been 

 made for almost every mile of the way. I regard the discovery of this 

 channel with considerable pride, as exceptionally complete results have 

 been obtained. These have been described in my book on Niagara. 2 

 However, since its publication additional borings have been made show- 

 ing its depth; which within the line of the escarpment reaches to a 

 depth at least 375 feet below the Erie level or 50 feet beneath the surface 

 of Lake Ontario. This one newly observed feature is worthy of record., 

 Thus this buried channel is sufficiently deep to have drained the Erie 

 basm without adding to it the effects of the recent earth-movements 

 These would reduce the floor of the channel to 500 feet below the present 

 lake level at Cleveland. Its breadth of a mile and a quarter to 2 miles 

 is small compared with that of the lake, but this is due to the protecting 

 effects of the harder capping rocks, while the channel itself was largely 

 made by the river flowing through it. 



Huron and Georgia Outlets 

 The connection between the Huron and Erie basins is entirely modern 

 the preglacial outlet of the upper valley having passed by way of Geor- 

 gian Bay to that of Lake Ontario (B on map), through a broad buried 

 valley, which I discovered in '1888.* This was excavated out of Hudson 

 River and Trenton formations; but the Huron drainage had also broken 

 across he Niagara belt (C on map). The outlet of the Huron Valley i, 

 now submerged between the Sangeen Peninsula and the islands, having a 

 breadth of 4 miles for the outer and 2 miles for the inner channel. H i 8 

 cut through the hard rocks into the softer strata, but here the channel is 

 more or less obstructed by drift. 



