3 io POPULAR SCIENCE MONTHLY 



as it must have been to account for the various observed phenomena — 

 such phenomena as would necessitate the occurrence of water loaded 

 with ice and detritus floating for centuries at least over a large part 

 of the earth's surface. 



His paper showed a very clear insight into what had taken place, 

 but an inability, with the information at that time available, to account 

 for it in a satisfactory manner. Thus, in describing the striae found 

 by himself on the top of hills and mountains like Monadnoc, he wrote : 



Could immense icebergs have been stranded on the northern slope of the 

 hills and afterwards, by the force of currents, have been driven over the sum- 

 mits; or would it be necessary to suppose that, after the stranding, the water 

 must have, risen so as to lift the iceberg; or would a vast sheet of ice lying 

 upon the earth's surface, by mere expansion, without the presence of water, 

 have been able to produce the smoothing and furrowing in question? 



After considering the phenomena and weighing all the theories 



advanced from time to time by the authorities quoted, he summed up 



the matter in the following words : 



Is it not possible that the phenomena of the drift may have resulted from 

 all the causes advanced in the theories under consideration? I feel . . . that 

 the proximate cause of the phenomena of drift has at last been determined, 

 namely, the joint action of water and ice. 



In 1836 there was organized a state geological survey of New York, 

 which was placed in charge of W. W. Mather, Ebenezer Emmons, 

 Lardner Vanuxem and James Hall — men whose names have since 

 become too thoroughly identified with American geology to ever become 

 eradicated. Naturally drift phenomena attracted the attention of 

 these workers, and each expressed opinions, some of which may be 

 referred to in detail. 



Seventy-five pages of Mather's report, as published in 1843, were 

 given up to descriptions and discussions of drift phenomena. He 

 concluded that the transport of the material and the production of 

 scratched surfaces were contemporaneous, the drift itself being trans- 

 ported in part by currents and in part by ice itself drifted by the cur- 

 rents. The period of the drift and that of the quaternary deposits 

 were separated by a partial submergence of the land, and, further, the 

 periods of the drift were periods when the currents were stronger than 

 at the present time. He conceived this to be due to a collapse of the 

 crust of the globe upon its nucleus, causing an acceleration of the 

 velocity of rotation, and this causing, in its turn, a disturbance of the 

 form of equilibrium of the spheroid of rotation which had been com- 

 pensated by the flow from the polar regions and an accelerated flow 

 to the equatorial regions. This sudden acceleration of the ocean cur- 

 rents he felt would be sufficient to cause the transportation of vast 

 quantities of detritus-laden ice from the polar regions southward. 

 The large amount of drift scattered over the central and northern 

 Mississippi region he ascribed incidentally to ice-laden currents from 



