CHAPTEK XXIII. 



THE GLACIAL EPOCH. EXISTING GLACIER REGIONS. 



I HAVE now to describe a remarkable episode in Post- 

 Tertiary times, known as the Glacial epoch, which 

 is certainly later than the latest beds of the Crag, and 

 is generally considered to be of later date than the 

 ' Forest bed ' of Cromer, on sound stratigraphical 

 evidence. The effect of local mountain glaciers, and 

 of far broader sheets of glacier ice that descended from 

 the mountains and overspread great plains, have left 

 unmistakable traces over large parts of the northern 

 and southern hemispheres ; and without going into all 

 the minutiae of the subject I shall be able to describe 

 the history of that period, as it affects the scenery of 

 Britain, with something like detail. Before doing so, 

 however, I must lead the reader into Switzerland, and 

 show what kind of effect is being produced there by 

 the ice of the present day, and afterwards into Green- 

 land and Victoria Land, and show what takes place 

 there, and then by the knowledge thus gained 1 shall 

 be able to return to our own country and explain what 

 took place here in that icy episode, which, measured by 

 ordinary standards, is far distant in time, but which, 

 by comparison with the more ancient periods, almost 

 approaches our own day. 



The first thing to be done is to explain what a 

 glacier is. In any large and good map of Switzer- 



