245 [Jackson. 



such case of groups of large rocky masses lying at the foot of the 

 Valdai Hills in Russia, some seven hundred miles from their ascer- 

 tainable source in Northern Sweden, or perhaps Lapland. 



I can add that I am familiar with the frequent occurrence of laro-e 

 sharply angular, wholly unworn blocks of stone imbedded in the fine 

 grained brick-clay of the Clyde Valley in Scotland, resting in the 

 undisturbed clay, and environed by fragile fossils, bearing no marks 

 of any commotion in the waters, and amid all the signs and proofs of 

 their having been freighted to where they rest, by ice rafts, and 

 let gently down into the clay by the gradual melting of the stranded 

 ice. 



Dr. C. T. Jackson fully concuiTed with the observations of 

 Prof. Rogers concerning the causes of the drift scratches, stat- 

 ing that there was no proof of their radiating from mountain 

 groups of small extent in Korth America. In the State 

 of Maine he had observed that the scratches inin around the 

 sides of the mountains, and were deflected into the valleys, on 

 the principle that the angle of reflection is equal to the angle 

 of incidence. In Rhode Island he had noticed boulders con- 

 taining iron ore that could only have come fi-om Cumberland 

 of that State, which were scattered on both sides of the 

 Providence River; that they diminished in size towards 

 the south, and had evidently been rolled and pushed for- 

 wards by strong aqueous currents. He had lately seen how 

 greatly the climate of a country could be lowered by cold 

 northern currents during his visit to the coast of California 

 The coast about San Francisco was chilled by the arctic cur- 

 rent flowing southward from Russian America, for while one 

 hundred miles in the interior the thermometer ranged from 

 105° to 110° during the summer, the same days in San Fran- 

 cisco it stood at 54° — 65°. The temperature was thus locally 

 lowered by the arctic currents impinging on this jDoint. 

 But four hundred miles southward, where Point Conception 

 deflects the arctic currents from Santa Barbara and Los 

 Angeles, he had experienced the midsummer temperature of 

 Naples. 



He said the rocks of the northern part of the country 

 were scratched and polished by the action of grounded ice- 

 bergs, and that the scratching and polishing could not be ac- 

 counted for by the glacial theory. Sir John Richardson had 



