19 



Thomas Workman, Esq., in the Chair. 



A Paper was read by Joseph John Mubphy, Esq., F.G.S., on 

 THE PROBLEM OF GEOLOGICAL CLIMATES. 



It has long been known that fossil remains of plants and 

 animals are found in the temperate and colder regions of the 

 earth, of similar species to those which are now found living in 

 much warmer climates, thus proving that, in remote geological 

 periods, what are now the temperate and cold latitudes were 

 much warmer than they are at present ; and evidence, mostly 

 of a different kind, consisting of ice-borne boulders and glacial 

 scratches on rock, has now made it equally certain that, in 

 comparatively recent geological periods, icebergs and glaciers 

 had a much greater than their present range. 



Various causes have been suggested for these changes of 

 climate. It was formerly a favourite idea, that in the early 

 geological periods the cold crust of the earth was thinner than 

 at present, and that the air was warmed by the earth's internal 

 heat. This, however, is now, I believe, universally abandoned. 

 Sir William Thomson and all the best authorities are agreed 

 that, so soon as the earth's surface was sufficiently cool and 

 consolidated to admit of vegetable and animal life on the land, 

 the escape of internal heat would be too small to have any 

 perceptible effect on the temperature of the air. 



It has been suggested that the solar system may be moving, 

 in the course of successive ages, through hotter and colder 



