No. 5.] SPENCER — SURFACE GEOLOGY. 279 



above all the great lakes, and even reaching in the region of our 

 Upper Great Lakes to a height of 1,000 feet above the sea, at 

 Maganetawan river (Bell). It occurs along Lake Ontario at the 

 mouth of Niagara river, at Thorold ond westward. In the eastern 

 part of the Dundas valley it has been pierced to the depth of 78 

 i'eet (6(» of which are below the level of the lake.) I am not cer- 

 tain of its occurrence in the upper part of the Dundas valley. 

 South of Brantford, Professor Bell estimates that it must have a 

 thickness of 70 feet, but in Walpole, some miles east of Brant- 

 ford, the coruiferous limestone comes generally to within a few 

 feet of the surface, whose soil is more or less of a clayey charac- 

 ter, filled with fragments of corniferous limestone (richly fossil- 

 iferousj. brought to the surface by frost. This clay also occurs 

 largely about Lake Erie. 



The Leda clay of the St. Lawrence valley was more or less 

 denuded before the deposition of the Saxicava sand. So also 

 the surface of the Erie clay was water worn or denuded by 

 subaerial actions. It is then overlaid (often unconformably) by 

 the S'fugeen day, which is brownish, in very thin beds (one 

 inch, often separated by sand or gravel, or deposited with inter- 

 calated beds of sand. This clay forms a heavy soil. In the 

 neighborhood of the Niagara river and elsewhere it contains 

 fresh- water shells. In the region about the western end of Lake 

 Ontario, much of the country is covered with this clay, or where it 

 is removed by Erie clay. But in the localities immiHliately in the 

 vicinity of the Niagara escarpment, and often in the Dundas 

 valley, we have the soils formed from the more modern ruins of 

 the Silurian rocks. 



In noticing the occurrence of the general deposit^ in Canada, 

 the boultlcr clay of the St. Lawrence appears to be wanting in 

 the western portion of the Province of Ontario. Tl^t- Erie clay, 

 containing boulders, and also angular fragments in part, has been 

 provisionally assigned as the equivalent of both the Boulder and 

 J^eda clays of the St. Lawrence valley. The Boulder clay is 

 unstratitied (or there are only very few feeble indications of stra- 

 tification), while the Erie clay is always stratified, showing differ- 

 ent conditions of deposits. Yet the Erie clay generally rests on 

 the striated Palaeozic rocks in Western Ontario. 



In the Dundas valley there is a deposit older than the terraces 

 {Jov terraces and sea-beaches occur above it), and possibly older 

 than the Erie clay, unless we consider this a hiirher ixTtion of it. 



