DESICCATION AS A PHASE OF THE GLACIAL EPOCH. 185 



been taking place, nor to connect these facts into a sequence the progression 

 of which indicates the constant action of cosmical agencies unbroken by 

 interruptions and antagonisms, for which no probable cause can be assigned, 

 and which are not in any degree in harmony with what, as we have abun- 

 dant evidence to prove, did take place during the preceding geological 

 periods. 



The view generally taken by geologists of the phenomena of desiccation, so 

 far as these are noticed at all, is, that they form a part of a series of events 

 which took place during the so-called " Glacial epoch;" or, rather, that they 

 are the necessary sequence of those events, and, so to speak, the " winding 

 up " of that epoch. 



The idea is, that at a certain period in the earth's history a refrigeration 

 of our planet caused the precipitation of certain regions to take the form of 

 snow exclusively, which being converted into ice became accumulated upon 

 the surface, and was thus laid away for use in future ages, just as the snow- 

 fall of the winter in high mountain regions, at the present time, furnishes a 

 supply of moisture by its melting during the succeeding summer. Accord- 

 ing to this view all indications of a former larger amount of moisture in any 

 particular region are referred, at once and without doubt, to the melting 

 of the " great glacier." If a lacustrine area exhibit signs of having dimin- 

 ished, it is because it was once larger, owing to the increased supply of 

 water to it during the melting of the ice of the Glacial period. So with 

 regard to all the other evidences of a larger amount of water carried off the 

 surface in various regions, such as is afforded by terraces and the like ; this 

 is all referred to the conclusion of the Glacial epoch, and considered as a 

 natural result of a more or less sudden melting of a great mass of snow and 

 ice previously stored away in the form of the " great ice-sheet." 



To illustrate the nature of tliis view, a few quotations may be introduced 

 from recent writers on this branch of geology. Mr. H. C Lewis, after de- 

 scribing the extensive deposits of rolled gravel of the valley of the Delaware, 

 and calling attention to the fact that the amount of water must once have 

 been much larger than it now is, says : " It is diflficult to imagine an origin 

 for such a flood as we have described other tlian the melting of a glacier. 

 We have shown that the flood was not an inroad fioni the sea, but tliat it 

 came down the valley. No rain-storms of modern experience could have 

 supplied such a flood. To call the time of this flood a ' Pluvial Epoch ' will 

 be of little assistance, since no origin for such extraordinary rains is sug- 



