CHAP, v.] CLIMATAL AND GEOGRAPHICAL CHANGES. 119 



4. A Reversion to a Severe Climate. 



The next change was one of climate, which reverted 

 to the cold condition of the second of these divisions. 

 Glaciers again covered the higher grounds, and icebergs 

 again floated over the lower grounds, still submerged, 

 depositing as they melted the upper boulder clay, which 

 rises as high as 500 feet above the sea-level in Lancashire 

 and Yorkshire (Hull). The drift of the icebergs was 

 south-easterly, since the peculiar altered chalk of Antrim, 

 in the north of Ireland, is scattered over Lancashire and 

 Cheshire, and as far south as Ironbridge in Shropshire. 



5. Period of Elevation Climate becoming Temperate. 



Then followed an upward movement of the land, 

 until the upper boulder clay became dry land, and 

 Britain and Ireland became part of the mainland of 

 Europe, as is represented in the Map (Fig. 32). Glaciers 

 still remained on the higher hills in Scotland, Wales, 

 and Cumbria, leaving in their retreat the old moraines, 

 so conspicuous in those regions. The climate was less 

 severe than in the preceding period, and was gradually 

 again becoming temperate. As the upper boulder clay 

 deposited on the sea-bottom became lifted up, it was 

 gradually covered by forests of yew, Scotch fir, oak, ash, 

 and alder, in which the Pleistocene mammalia found 

 ample food in the eastern and midland counties. 



Climatal Change on the Continent, and in Asia 

 and Africa. 



Similar climatal changes have left their mark upon 

 the higher mountains of Europe, Asia Minor, and North 



