102 Glacial Action ceased at North Latitude 35°. 



Moreover, there is no ground, at present, to doubt the 

 simultaneous dispersion of the erratics over Northern Europe 

 and Northern America. So that the cause which transported 

 them, vrhatever it may be, must have acted simultaneously 

 over the whole tract of land west of the Ural Mountains, and 

 east of the Rocky Mountains, without assuming anything re- 

 specting Northern Asia, which has not yet been studied in 

 this respect ; that is to say, at the same time, over a space 

 embracing two hundred degrees of longitude. 



Again, the action of this cause must have been such, and 

 I insist strongly upon this point, as a fundamental one, the 

 momentum with which it acted must have been such, that 

 after being set in motion in the north, with a power sufficient 

 to carry the large boulders which are found everywhere over 

 this vast extent of land, it vanished, or was stopped, after 

 reaching the thirty -fifth degree of northern latitude. 



Now it is my deliberate opinion that natural philosophy 

 and mathematics may settle the question, whether a body of 

 water of sufficient extent to produce such phenomena can 

 be set in motion with sufficient velocity to move all these 

 boulders ; and nevertheless stop before having swept over 

 the whole surface of the globe. Hydrographers are fami- 

 liar with the action of currents, with their speed, and with 

 the power with which they can act. They know also how 

 they are distributed over the globe. And, if we institute a 

 comparison, it will be seen that there is nowhere a current 

 running from the poles towards the lower latitudes, either in 

 the northern or southern hemisphere, covering a space equal 

 to one-tenth of the currents which should have existed to 

 carry the erratics into their present position. The widest 

 current is west of the Pacific, which runs parallel to the 

 equator, across the whole extent of that sea from east to 

 west, and the greatest width of which is scarcely fifty de- 

 grees. This current, as a matter of course, establishes a 

 regular rotation between the waters flowing from the polar 

 regions towards lower latitudes. 



The Gulf Stream, on the contrary, runs from west to east, 

 and dies out towards Europe and Africa, and is compensated 

 by the currents from Baffin's Bay and Spitzbergen emptying 



