276 NEOZOIC TIME. [CHAP. XIII. 



have yielded numerous remains of the reindeer, Irish 

 elk, &c. 



Submerged forests are of frequent occurrence round the 

 western, southern, and eastern coasts ; they pass below low- 

 water mark, and peat is said to have been found in some 

 places below four or five fathoms of water. In the estuary of 

 the Barrow the depth of alluvial matter extends to between 

 60 and 70 feet below high- water mark. 1 



2. Physical History and Geographical Changes. 



Amid the conflicting opinions which are held by different 

 geologists regarding the physical conditions that prevailed 

 during the early part of the Pleistocene period, it is very 

 difficult to come to any decided conclusion. Everyone 

 admits that it was a time when the action of ice was para- 

 mount, but what form of ice chiefly prevailed over the 

 British Islands at the climax of this ice age, and whether 

 at this particular epoch the land surface stood at a higher 

 level than now, or was submerged beneath the waters of an 

 ice-laden sea, are matters of dispute. 



That this should be the case with a period of such a late 

 geological date, of which we have such complete records, 

 and of which so many competent observers have made a 

 study, might be deemed a remarkable fact, and one that 

 did not redound to the credit of geologists generally ; but 

 the prevailing uncertainty is, without doubt, caused by the 

 difficulty of realizing the exceptional conditions which must 

 have existed in the British area at this time. The ice- 

 regions of the present day are difficult of access, and we 

 cannot study the action of ice-masses with the same facility 

 that we can observe the action of rivers or of sea- waves. 

 Here and there we may find a retreating glacier, and can 



1 Kinahan, '' Geology of Ireland," pp. 265 and 266. 



