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INTRODUCTION. 



The sharp escarpment (Niagara cuesta) which separates 

 the upland of western Ontario from the lowland to the 

 east extends from Queenston on the Niagara river to 

 Hamilton at the head of Lake Ontario and thence north- 

 ward into Bruce peninsula between Lake Huron and 

 Georgian bay. As the difference in elevation between 

 lowland and upland is about 350 feet (106 m.) excellent 

 rock exposures are presented where the face of the escarp- 

 ment is abrupt. The strata revealed in the southern part 

 of the escarpment consist of the uppermost member of 

 the Ordovician (Richmond) and the lower beds of the 

 Silurian. Towards the north still lower Ordovician 

 strata are exposed. The more favourable points for the 

 study of sections are the following: — 



Niagara gorge. (See Excursion B 1.) 



Grimsby, half way between Niagara and Hamilton. 

 (Present Excursion). 



Hamilton, at the head of Lake Ontario. (Present 

 Excursion). 



Credit Forks, about 50 miles (80 km.)north of Toronto. 

 (See Excursion B). 



Collingwood, on Georgian bay. (See Excursion C 5). 



A generalized section of the cuesta showing the 

 actual strata is indicated in the central column of the 

 accompanying table. The stratigraphic classification 

 adopted in the latest publications of the State of New 

 York is shown on the left. The right hand column pre- 

 sents a classification which has been recently proposed. 



