156 DR. J. MOEISON — ICE AND ITS WOEK. 



was laid clown, the greater part of our island was doubtless 

 submerged. 



The fact that boulder-clay is found over such wide expanses of 

 country shows us that at one time the cold was so intense that not 

 only did glaciers fill our mountain-yalleys, but that a great ice-cap 

 was formed Avhich enveloped the whole country except the extreme 

 south of England. The presence of Arctic shells in the boulder- 

 clay in some situations shows us that the ice was pushed out for 

 some distance from the land into the shallow seas surrounding our 

 island. The presence and universality of glacial drift show us 

 that our country, except the highest mountain-summits, was sub- 

 merged beneath the waters of an icy sea, in which icebergs and 

 ice-rafts carried and scattered rocky delris far and wide. 



