54 



\oth January, 1882. 



The President, Robert Lloyd Patterson, Esq., in the Chair. 



A Paper was read by Joseph J. Murphy, Esq., F.G.S., on 

 THE RAINY OR POST-GLACIAL PERIOD. 



The views of the lecturer on the nature and cause of the glacial 

 climate were submitted to the Society, on the 1st Dec, 1875, 

 and on the 21st December, 1880;— both papers were fully 

 printed in the Proceedings, so that it is not necessary to say 

 anything here respecting the astronomical causes of glaciation. 

 It is enough to repeat the conclusion there stated, that glacia- 

 tion was due neither to great winter cold nor to low mean 

 annual temperature, but chiefly to a cold summer which left 

 the snow of winter unmelted, and partly to a great snowfall 

 during winter. If any form of the astronomical theory of 

 glaciation is true, the whole earth was never glaciated at the 

 same time, but the northern and southern hemispheres were 

 glaciated alternately ; the epochs of maximum glaciation of the 

 two hemispheres being separated from each other by an interval 

 of 10,500 years. In each hemisphere there was consequently a 

 succession of glacial periods, with a succession of non-glacial 

 periods alternate with the glacial ones. Mr. Croll, in his work 

 on Climate and Time, has submitted evidence of this inter- 

 mittent character of the glacial climate. 



On the astronomical theory of the glacial climate, these alter- 

 nate glacial periods in the two hemispheres succeeded each 

 other during the continuance of a much longer period, during 



