1826.] Geological Society. 461 



are new, and of these nearly 300 are of the first class. He 

 extends the examination to all stars of the 8th and (8"9) mag- 

 nitude. 



The author, after detailing a few more preliminary remarks, 

 enters into a comparison of many of his observations with those 

 of Sir W. Herschel, and of Messrs. Herschel and South, point- 

 ing out many cases in which their coincidence is truly re- 

 markable ; — others in which there are discrepancies, evidently 

 attributable to the relative or real motions of the stars in the 

 intervals between the observations ; — others in which the di- 

 versities seem occasioned by the instruments employed ; — and 

 others in which there are anomalies which do not, as yet, admit 

 of explanation. This part of M. Struve's communication is 

 not susceptible of abridgement. 



GEOLOGICAL SOCIETY. 



May 5. — The reading of Dr. Bigsby's paper, on the Geology 

 of the Valley of the St. Lawrence, was continued and coa- 

 cluded. 



In the first part of this paper, the author describes the general 

 form of the country, in which are placed the great lakes of 

 Superior, Huron, Erie, and Ontario, with a sketch of some of 

 the rocks occurrnig in their vicinity. 



He then examines the question of the present level of their 

 waters, as compared with their ancient level, and enumerates 

 many circumstances to prove that no recent alteration has taken 

 place. He then endeavours to establish, that the Canadian 

 lakes are monuments of the last flood, by the features of the 

 country, the abrasion of its rocks, and the nature of the trans- 

 ported matter. He ascribes the shape of the Islands of Lake 

 Superior, and of the Promontory of Keweewoonan, to diluvial 

 denudation. The Manitouline gaps are adduced as effects of 

 one simultaneous deluge. 



Dr. Bigsby divides the debris of the St. Lawrence Valley 

 into four classes: — 1. Diluvial; 2. Messalluvial ; 3. Alluvial; 

 4. Native, 



1 . The diluvium lies usually in extensive flattened heaps. 

 Cape Tourment, 1800 feet above the level of the sea, is covered 

 with it. Marine shells, of the genus Saxicava, are found in the 

 Ottawa, 300 miles N.N.W. of Montreal. 



The actual position of numerous primitive bowlders on the 

 plains being south and south-east of their original sites, in- 

 dicates that the flood proceeded from the north and north-west, 

 or, in a direction contrary to the present course of the St. Law- 

 rence. The trap of Montreal is found at Lake Champlain, and 

 bowlders of tabular spar (one of which vveiglis (500 pounds) are 

 traced to the west end of Ontario, where the Ophicalcic rock 

 is also seen in broken masses. The chalcedonies from Lake 

 Superior have been transported south-west to Lake Pepin. The 



