212 THE BOOK OF NATURE STUDY 



movement. This ridged up the strata in lines running either 

 north and south in the Pennine Chain, or east and west in the 

 Mendips and South Welsh mountains, a line which was con- 

 tinued, though the continuation is now hidden, eastward under 

 the Weald and across to France and Belgium. Such features as the 

 Pennine and Pendle Ranges, the higher ground of the Midlands, the 

 South Welsh mountains, the Mendips, and the region of Dartmoor, 

 Exmoor, and the mountains of Southern Ireland, were added to 

 British geography. And, associated with them come the remark- 

 able terrestrial, shallow water, and lacustrine deposits of the 

 Permian Period, and the river and salt-lake deposits of the Trias. 

 The mountains were denuded by frost and torrents, and breccias 

 and conglomerates deposited. The obstruction of rain-bearing 

 winds by the southern range converted the continental area into 

 a rainless one with deserts and salt lakes, deprived it of marine 

 deposits and life, and was responsible for the remarkable character 

 of such rocks as were deposited. The volcanoes of the Permian 

 and the vast amount of granite intruded into the earlier rocks of 

 Southern England at this period are further consequences of the 

 great earth-movement. 



The marine deposits of the Jurassic and Cretaceous Systems 

 which follow are the natural consequence of the period of rest, 

 which was on the whole an extremely quiet one. But these 

 Formations when traced from place to place prove to have their 

 shore deposits in association with the features just outlined, the 

 Pennine, and the great southern (or Armorican) ridge running 

 east and west. Part of the shore-lines were, however, made of the 

 relics of the still earlier features resulting from the Caledonian 

 movement, which, indeed, survive to this day in sufficient pro- 

 minence to form our chief mountain ranges. 



The last great movement, the Alpine or Wealden movement, 

 was responsible for lifting the sea in which the Chalk was formed 

 into the shallow water in which the Tertiary rocks were laid down. 

 But the movement reached its maximum after the Oligocene 

 Period, when all Britain was lifted above the sea and the great 

 east and west fold of the Weald and Salisbury Plain was formed, 

 together with the London and Hampshire Basins. At the same 

 time, but along lines determined mostly by earlier movements, 



