﻿G. 31. Daicson — Geology of British Columbia. 373 



Silurian age, aud they indicate certain theoretical conclusions which 

 follow from this determination. 



9. " On the Superficial Geology of British Columbia." By George 

 Mercer Dawson, Esq., F.G.S., Assoc, E.S.M., of the Geological 

 Survey of Canada. 



The author stated that the rock-striation and fluting on the south- 

 eastern peninsula of Vancouver's Island shows that at one time a 

 great glacier swept over it from N. to S., filling the Strait of Georgia, 

 50 miles broad in places, and having near Victoria a thickness of ice 

 of over 600 feet. Traces of this glacier also occur on San Juan 

 Island, and on the coast of the mainland. The deposits immediately 

 overlying the glaciated rocks, besides what may be moraine profonde, 

 locally developed, are sandy clays and sands, arranged in water, and 

 sometimes containing marine shells. The lower beds, at least, of 

 these, were probably formed at the foot of the retreating glacier, the 

 sea standing considerably higher than at present. The northern part 

 of the Strait of Georgia and the fjords opening into it, and the fjords 

 north of the Strait, show ice-action to a height of above 3000 feet. 

 Terraces on tho coast of the mainland are rare, and never at great 

 elevations. 



The interior plateau of British Columbia shows a system of 

 glaciation from. N. to S., traces of which have been observed above 

 3000 feet. Subsequent glaciation radiating from the mountains 

 also occurs. The superficial deposits here are either unmodified or 

 modified. The former, representing the Boulder-clay, occurs at 

 nearly all heights up to over 5000 feet; the latter chara.cterizes 

 nearly all localities below 3000 feet, and is most extensively 

 developed in the northern low country, where it forms a white 

 silt or loess. The interior is marked with shore-lines and terraces 

 up to 5270 feet. Moraines occur in great numbers, most of them 

 marking stages in the retreat of glaciers towards the mountains, 

 although some may have been formed in connexion with, the N-. and 

 S. glaciation. 



The sequence of events in the interior, according to the author, 

 seems to have been as follows :: — Glaciation from N. to S., with 

 deposit of Boulder-clay ; formation of terraces by lowering of water 

 surfaces, accompanied or followed by a warm period ; advance of 

 glaciers from, the mountains, and formation of lower terraces ; and 

 retreat of glaciers to their present limits. The glaciation of Van- 

 couver's Island may have occurred during both cold periods or during 

 the second only. 



The author considers the assumption of the production of the 

 N. to S. glaciation by an ice-cap. to be attended with great difficulties, 

 and seems to favour the notion of its being effected by the accumu- 

 lation of ice on the country itself, and especialty on the mountains 

 to the N.j filling the central plateau in going southward, and passing 

 seaward through the gaps and fjords of the coast range. 



10. " The Exploration of the Ossiferous Deposit at Windy Knoll, 

 Castleton. Derbyshire, by Eooke Pennington, Esq., LL.B.. F.G.S., 

 and Prof W. Boyd Dawkins." By Prof. W. Boyd Dawkins> M.A., 

 F.E.S., F.G.S. 



