38 THE CANADIAN NATURALIST. [Vol. ix, 



come from the mainland. Along the eastern shore of Graham 

 Island, a long line of cliffs displays deposits of clays and sands- 

 similar to those previously described as occurring in the southern 

 part of Vancouver Island. Many of the beds contain boulders 

 and some hold marine shells of the species found in the deposits 

 just referred to, with occasional fragments of wood. 



Quite recently, a great addition to our knowledge of western 

 geology has been made by the publication by Clarence King of 

 the volume of his series on the fortieth parallel, devoted to sys- 

 tematic geology. In this the quaternary period is treated at 

 some length, and in a comprehensive manner, enabling compari- 

 sons to be drawn between the condition during the glacial period 

 of that part of the Cordillera system included in British Colum- 

 bia, and its southern continuation in the vicinity of the fortieth 

 parallel. 



King has failed to find any evidence of a great southward- 

 moving ice-mass, or general glaciating agent, and no sheet of 

 boulder-clay covers the region ; the superficial deposits being 

 either directly due to the descent of torrents from the mountains 

 and high lands, or to the rearrangement of these by water action 

 in lakes. Two great sheets of water which have been called Lakes 

 Lahontain and Bonneville, spread widely in the high plateau 

 region between the Sierra Nevada and the Rocky Mountains. 

 Local glaciers were, however, extensively developed, coming down 

 to altitudes of 2000 to 5000 feet above the sea in the Sierra 

 Nevada, which was exposed to the moisture-bearing winds of the 

 Pacific, but seldom reaching below a height of 7000 to 8000 feet 

 in the dryer eastern ranges. These constitute the local expres- 

 sions of the general change which further north produced great 

 ice-fields, but at no time was more than about one-thirtieth of the 

 area embraced in the fortieth parallel survey covered with ice. 



The most interesting point established by King, however, is 

 the existence of two periods of moisture and flooding of the lake 

 basins, alternating with two of extreme drought, the latter of 

 which still continues. The evidence of these is found both in 

 the relative arransjement of the stratified and unstratified mate- 

 rials of the old lake bottoms, and in the chemical character of 

 the deposit from their waters. These periods of great precipi- 

 tation are correlated with great probability with the two epochs 

 of glaciation proved in British Columbia. King, however^ 

 adopts extreme views as to the power of glaciers in eroding 



