584 AN OUTLINE OF THE GEOLOGY OF ONTARIO. 



an extinct species of elephant; and tlie mastodon, a related but en- 

 tirely extinct proboscidean genus. 



The Erie and Huron district is another agricultural region of great 

 fertility. It lies immediately west of the Lake Ontario region, and 

 is separated from the latter by the line of the great Niagara escarp- 

 ment, which runs from the Niagara River, by Queenstown, Thorold, 

 Hamilton, Dundas, etc., to Cabot's Head, on Goorgian Bay. It thus 

 forms, for the greater part, an elevated table-land, bounded on the 

 south by Lake Erie, and on the west by Lake Huron. Along its 

 eastern and north-eastern edge, as well as in its central portion, the 

 district lies at an average elevation of from 1,200 to 1,300 feet above 

 the sea; but the ground slopes gradually to Lake Erie, 565 feet, and 

 to Lake Huron, 578 feet above the sea-level. Its surface, except 

 where cut by river -valleys, is generally even; and it presents a marked 

 contrast to the lower region of Lake Ontario, by the almost total ab- 

 sence of inland bodies of v^ater. It is traversed, however, by many 

 important rivers — as the G-rand River, flowing into Lake Erie; the 

 Thames, flowing into Lake St. Clair; and the Maitland and Saugeen, 

 flowing into Lake Huron. The eastern and north-eastern escarpment 

 is also cut through by numerous smaller streams, which thus flow 

 through deep ravines, many of which are of a very wild and pictu- 

 resque character. The strata of the district consist of the Middle 

 and Upper Silurian, and various Devonian formations. These suc- 

 ceed each other generally from north-east to south-west, and comprise 

 In ascending order the Clinton, Niagara, Guelph, Onondaga or Gyp- 

 siferous, Lower Helderberg or Eurypterus, Oriskany, Corniferous, 

 Hamilton or Lambton, and Chemung-Portage formations. These 

 strata, although practically undisturbed, are afiected by several mod- 

 erate anticlinals running across the more central part of the district 

 in a general east and west or south-west direction; and it is thought 

 that the petroleum of this part of the region has been brought towards 

 the surface by fissures resulting from these anticlinals. A transverse 

 or nearly north and south fold, forming a trough or synclinal filled 

 with higher'Devonian strata (of the Hamilton or Lambton formation), 

 also occurs in the south-western portion of the district between Lake 

 Erie and the south point of Lake Huron. Finally, it may be ob- 

 served, that the strata of the district generally are much overlaid by 

 boulder-clays, sands and gravels of the Glacial and Post-Glacial 

 periods. These agree generally with deposits of the same age occur- 



