36 BULLETIN OP THE 



time of submarine volcanoes which supplied the vapor ; the cold 

 being due to that of the higher atmosphere brought down by the 

 snow from that region. 



He also remarked on the great irregularities, which were pro- 

 bable. Catastrophes may have occurred when there were sudden 

 eruptions of vapor, and great geological changes. 



Mr. HiLGARD referred to the rapid accumulation necessary to 

 account for animals overtaken and buried in the snow. The ac- 

 cumulation would be more or less rapid, and the time required 

 less or greater, as the precipitation in winter exceeded the evapo- 

 ration in summer. 



Mr. Bessels referred to the very slow changes in the glaciers 

 of the Arctic regions at the present time. 



Mr, Endlich spoke of the impossibility of determining whether 

 the glacial formations were rapid or slow ; and of the very long 

 time required for geological changes. 



Reference having been made to the elephants and mammoths 

 found embedded in frozen earth in Siberia, Mr. Gill remarked 

 that it was not necessary to suppose a warm climate as neces- 

 sary to their existence, as there were indications that these ani- 

 mals had become adapted to a quite cold climate ; and instanced 

 lions and tigers, usually regarded as tropical animals, as found 

 at the present day in the neighborhood of the Amoor River, and 

 adapted by a vigorous growth of hair to live in cold regions. 



He further remarked that from animal remains it would seem 

 that the preglacial period was warm, and that there followed a 

 diminution of temperature until a minimum was reached in the 

 glacial period. In the miocene period there was warm water 

 and a warm temperature in the north ; and there were, doubtless, 

 gradations while these mammoths existed ; and finally it became 

 too cold for their existence, and they died out. He concluded 

 that the transition from the miocene to the glacial period may 

 have been gradual. 



Mr. Dall remarked that the mammoths in Alaska must have 

 lived through the glacial period. The ice-cliffs in that region 

 must have been formed in a period of intense cold. Glaciation 

 was not the same in different regions of the north. 



He referred, also, to the source of ivory on the northern coast 

 of Siberia, remarking that the animals may have been caught in 



