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AN OUTLINE OF THE GEOLOGY OF ONTARIO, 



Based on a Sub-Division op the Pboyince into Six >rATU'EAL Districts. 



By E. J. CHAPMAN, Ph. D., 

 Professor of Mineralogy and Geology in University College, Toronto. 



Communicated to the Canadian Institute, March 27th; 1875. 



The Province of Ontario, regarded in its natural features, admits 

 of a sub-division into six areas, more or less distinct in their physical' 

 and geological characters. These areas or districts succeed each other 

 from east to west in the following order: — -(1) The Lower OttaAva 

 district; (2) The Gananoque and Back Townships district; (3) The 

 Lake Ontario district; (4) The Erie and Huron district; (5) The 

 Manitoulin district; and (6) The district of the Upper Lakes. 



The Lower Ottawa district is an essentially agricultural area, under- 

 laid by Palaeozoic rocks in comparatively undisturbed stratification. 

 It occupies the country between the right bank of the Ottawa and 

 the left bank of the St. Lawrence, extending to the Province bound- 

 ary near the junction of these rivers. On the west, it is bounded by 

 a line extending roughly from. Brockville to the vicinity of Perth, 

 and from the latter point to the Ottawa a little north of the mouth 

 of the Madawaska. It lies at an average height of from 250 to 

 300 feet above the. sea, and presents a generally level surface. 

 Here and there, however, some bold escarpments occur, especially 

 around Ottawa City. These are mostly connected with faults. 

 In other places, somewhat extensive swamps prevail; but viewed 

 generally, the district is well timbered and of good fertility. A 

 broad synclinal, with an intermediate fold, forms the floor of the 

 country between the two rivers. The strata of the district belong to • 

 the Lower Silurian Series, but they ai'e overlaid in many places by 

 Drift deposits and more recent superficial accumulations. The Lower 

 Silurian beds comprise representatives of the Potsdam, Calciferous, 

 Chazy, Trenton, Utica, and Hudson River formations. The Potsdam 

 strata are mostly sandstones and quartzose conglomerates, with a few 

 interstratified beds of dolomitic limestone. They form, a more or less 



