66 



lomitic deposits, and adopts in part the theory which derives them 

 from the mechanical destruction of the rocks of the carboniferous 

 order. He states however two facts, which seem to imply that the 

 waters of the ocean had a power of separating carbonate of mag- 

 nesia from the pre-existing rocks, in a manner which is not ex- 

 plained by the mere mechanical hypothesis : — 1st, the greater abun- 

 dance of magnesia than could have been supplied by the dolomites of 

 the carboniferous limestone j 2ndly, the fact that some beds contain a 

 greater proportion of magnesia than is found in true dolomites. — 

 Whatever may have been the origin of the whole system ; its extent, 

 regular subdivisions, and characteristic organic remains, seem to 

 prove, that it originated in the long continued and consistent opera- 

 tion of powerful causes, acting simultaneously in distant parts of the 

 earth. 



March 21. — Benjamin Silliman, M.D. LL.D. of Yale College, 

 North America, was elected a Foreign Member of this Society. 

 Francis Finch, Esq. and Thomas Winter, Esq., both of West Brom- 

 wich, Staffordshire, were elected Fellows of this Society. 



A Paper was read, entitled " Topographical and Geological No- 

 tices, from information collected during the Expedition to the North- 

 west coast of America under the command of Captain Franklin ; by 

 John Richardson, M.D. F.R.S., &c." 



The expedition under Captain Franklin having arrived at their in- 

 tended winter quarters on the shore of Great Bear Lake, examined 

 in 1825 the vicinity of that lake, and the course of the Mackenzie 

 River from thence to the sea. The author subsequently accompanied 

 Captain Franklin down the river, as far as Point Separation, in lat. 

 67° 38' ; from whence the latter proceeded westward to lat. 70° 26', 

 long. 148° 52' : — the extreme western point seen by the expedition 

 being in long. 149° 37' west. Dr. Richardson at the same time 

 went eastward to the mouth of the Copper Mine River, and thence 

 returned overland and across the Great Bear Lake, to the head- 

 quarters. 



This Paper contains an account of the specimens collected, and the 

 geological observations made by both divisions of the party ; and 

 gives in considerable detail a description of the vicinity of Great Bear 

 Lake, with a more general one of the banks of the Mackenzie and 

 of the coast to the East of it ; to which are subjoined some observa- 

 tions respecting the country previously passed over by the expedi- 

 tion, between Lake Superior and Fort Franklin. The distances 

 traversed being, in latitude, about 23 degrees N. of Lake Supe- 

 rior ; and in longitude, altogether about 80 degrees ; — 60 degrees 

 to the west of Lake Superior, and 20 degrees on the coast, east- 

 ward from the mouth of the Mackenzie. The total extent passed 

 over in America by the expedition, in going and returning, was about 

 14,000 miles ; and that surveyed and laid down for the first time on 

 the maps, is about 5000 miles. 



The author however mentions, that a very limited portion of his 

 time could be devoted to geological researches ; the ground being for 



