582 AN OUTLINE OF THE GEOLOGY OF ONTARIO. 



district are as a rule practically free from titanium. Again, tlie over- 

 lying Huronian and copper-holdiiig rocks of Lake Huron and Lake 

 Superior, with their associated beds and dykes of trappean rock, have 

 have not been recognized in the Gananoque district. The mean ele- 

 vation of the latter above the sea is probably about 800 feet. Its 

 surface throughout is more or less of a broken, hilly character, with 

 vast masses of bare Laurentian rock standing in many places high 

 above the ground ; and numerous lakes occur along its southern bor- 

 der, and within its area generally. Although not favorably adapted, 

 as a rule, for agricultural occupation, the district contains valuable 

 economic minerals, The principal of these comprise: the iron ores 

 of MclSTabb, Bedford, Crosby, Sherbrook, Madoc, Marmora, Belmont, 

 Minden, Snowdon, etc.; the auriferous mispickel of Marmora and' 

 adjacent townships; the galena of Frontenac, Gal way, etc.; the apa- 

 tites of Burgess and Elmsley; the mica of Burgess; and the marbles 

 of the townships of Barrie, Elzevir, and surrounding country. 



In the Lake Ontario District we come again upon an agricultural 

 area, underlaid by limestones, shales, etc., in comparatively undis- 

 turbed stratification. This district ranges along the entire . north 

 and west sides of Lake Ontario. Its eastern and northern limits 

 are bounded by the crystalline Gananoque district described above. 

 Its western boundary is the high escarpment which runs from the 

 Niagara River by Queenston, Hamilton, Dundas, Georgetown, etc., 

 to Cabot's Head on Georgian Bay. From that point the district 

 forms the shore of the bay to a little beyond the mouth of the River 

 Severn. As regards surface features, it presents btit few marked ine- 

 qualities of level. The ground rises gradually from Lake Ontario 

 (232 feet above the sea) in a series of ridges or terraces running in a 

 general east and west direction. These ridges are composed of Drift 

 materials, mostly sand and gravels filled with boulders of various 

 kinds, brought down from northern sources during the Glacial Epoch, 

 probably by floating icebergs. The highest ridge in Albion and King 

 townships has an elevation of from 700 to 750 feet above Lake On- 

 tario, but becomes gradually lower in its eastern extension. Lake 

 Simcoe to the north is 704 feet above the sea, and Balsam Lake (the 

 northern part of which runs into the ciystallin.e area already des- 

 cribed) is still higher, its elevation being 820 feet above the sea. Bel- 

 mont Lake and Bice Lake are each nearly 600 feet, and Scugog Lake 

 (ill the midst of the drift ridges) nearly 800 feet above the sea level, 



