GEOLOGY. 181 



from the north, depositing boulder -drift in the north and 

 clay in the south of Russia. This state of things was finally 

 put an end to by the cutting of the channel of the Bospho- 

 rus, through which the waters found an exit southward. 



GLACIAL PHENOMENA AROUND LAKE ONTARIO. 



George J. Hinde has studied the Post-tertiary deposits near 

 Toronto, which throw new light on the geology of that re- 

 o-ion. The eroded Loraine or Cincinnati shales are here over- 

 laid by a considerable thickness of boulder-clay, including a 

 veritable pavement of striated boulders. Overlying this are 

 thinly stratified sands and clays, which have a maximum 

 thickness of 140 feet, and contain remains of plants, chiefly 

 mosses, with some mollusks and Crustacea, showing this to 

 have been a lacustrine deposit. These are conformably over- 

 laid by about forty feet of sand. Subsequent erosion has cut 

 in one case a valley in these stratified deposits to a depth of 

 more than one hundred feet, and the clay beds in the vicinity 

 of the erosion are often curiously contorted. Over this is a 

 second boulder-clay, filling up the depressions, and covering 

 over the higher portions to a depth of seventy feet. This is, 

 in its turn, overlaid by a second series of stratified clays with- 

 out observed organic remains, upon which appears in one 

 place a stratum of about thirty feet of what is regarded as a 

 third deposit of boulder-clay, succeeded by stratified sands 

 and gravels. 



To correlate these deposits, studied by Mr. Hinde, with the 

 clays of the regions farther south and west will require 

 further' study. The evidence of more than one period of 

 erosion was many years since pointed out by the present 

 writer, who showed the existence of a vast rock-basin cut 

 out of the Devonian strata, and filled up with clays, out of 

 which latter deposit the basin of Lake St. Clair and that of the 

 southwestern half of Lake Erie were subsequently eroded, the 

 stratified clays on the shores of the latter reaching to depths 

 far below the bottom of the lake. 



GLACIAL PHENOMENA IN LABRADOR. 



Henry Youle Hind has studied the joint action on the 

 Labrador coast of the polar current and of the sheets of ice 

 called by the fishermen pans (/. e., panes). These are great 



