TIIK PLKI8TO( F.M: SKIIIKS f.l'.i 



from tin- north. Pembrokeshire on tin- other hand has been 

 glaciated ly ire coming in from tin- Irish Channel (We map, Fig. 203). 



C. THE GLACIAL DEPOSITS OF BRITAIN 



No classification of the Glacial drifts has yet been proposed 

 which is applicable to all parts of the British Isles. In some 

 areas it is possible to establish a local succession of deposits, but 

 all attempts to correlate those of one area with a similar series in 

 another area have hitherto broken down. 



In some districts, such as Aberdeenshire, Norfolk, North Wales, 

 and the south-east of Ireland, there are certainly older and newer 

 boulder-clays, differing in colour and contents, and in some places 

 they are separated by stratified sands and gravels. We may safely 

 inter that such different deposits were formed during different 

 successive phases of the Glacial Period. In Germany the Glacial 

 deposits appear to exhibit a greater uniformity, and it is generally 

 held that there are two boulder -clays, a lower and an upper, and 

 that they indicate two epochs of advance and retreat of the 

 northern ice. 



The great variation observable in the Glacial deposits of Britain 

 is doubtless due to their being the product of several distinct ice- 

 sheets coming from different directions. This is especially the 

 case in England, where the influence of no fewer than five ice-sheets 

 can be distinguished (see map, Fig. 203). At present, therefore, 

 the British deposits can only be described in a piecemeal fashion, 

 and brief accounts will be given of those found in the following 

 areas : 



1. Central and Northern Scotland. 



2. South Scotland and the north of England. 



3. Yorkshire and Lincolnshire. 



4. East Anglia. 



5. The liidlanda. 



6. Wales and the West of England. 



7. Ireland. 



1. Central and Northern Scotland 



The Glacial deposits of Scotland may be classified as follows, 

 but it is seldom that all the members are found in one locality, 

 and it is probable that the moraines were more or less contempora- 

 neous with the later shell-bearing clays : 



4. Moraines of local glaciers. 



3. Shell-bearing clays near tin: coast. 



2. Upper houlder-clays with stratified sands and gravels. 



1. Lower boulder-clay or till. 



