172 DISCUSSIONS IN CLIMATOLOGY. 



can be obtained for the assumption of a periodical 

 alternation of warm and cold climates on the surface 

 of the earth." 



Evidence of Glaciation during the Tertiary Period. 

 — Evidence of glaciation during the Miocene period is, 

 I think, afforded by the well-known conglomerates 

 and erratics near Turin, first described by M. Gastaldi. 

 Beds of Miocene sandstone and conglomerate, with an 

 intercalated deposit containing large angular blocks of 

 greenstone and limestone have been found. Some of 

 these blocks are of immense size. Many of the stones 

 in the deposit are polished and striated in a manner 

 similar to those found in the boulder-clay of this 

 country. It has been shown by Gastaldi that these 

 blocks have all been derived from the outer ridge of 

 the Alps on the Italian side — namely, from the range 

 extending from Ivrea to the Lago Maggiore, and, 

 consequently, they must have travelled from twenty 

 to eighty miles. So abundant are these large blocks 

 that extensive quarries have been opened in the hills 

 for the sake of procuring them. The stratification of 

 the beds amongst which the blocks occur sufficiently 

 indicates aqueous action and the former presence of 

 the sea. That glaciers from the southern Alps 

 actually reached to the sea and sent adrift their 

 icebergs over what are now the sunny plains of 

 Northern Italy, is proof that during that cold period 

 the climate must have been very severe. One 

 remarkable circumstance, indicating not only the 

 glacial condition of the bed in which the blocks occur, 

 but also that this glaciation was the result of eccen- 

 tricity, is the fact that the bed is wholly destitute of 

 organic remains, while they are found abundantly both 

 in the underlying and overlying beds. 



Evidence of glaciation during the Eocene period, as 



