EXTINCT GLACIERS IN WALES. 265 



CHAPTER XIV. 



CHRONOLOGICAL RELATIONS OF THE GLACIAL PERIOD AND 

 THE EARLIEST SIGNS OP MAN'S APPEARANCE IN EUROPE, 



Continued. 



SIGNS OF EXTINCT GLACIERS IN WALES GEEAT SUBMERGENCE OF 



WALES DURING THE GLACIAL PERIOD PROVED BY MARINE SHELLS 



STILL GREATER DEPRESSION INFERRED FROM STRATIFIED DRIFT 



SCARCITY OF ORGANIC REMAINS IN GLACIAL FORMATIONS SIGNS OF 



EXTINCT GLACIERS IN ENGLAND — ICE-ACTION IN IRELAND MAPS 



ILLUSTRATING SUCCESSIVE REVOLUTIONS IN PHYSICAL GEOGRAPHY 



DURING THE POST-PLIOCENE PERIOD SOUTHERNMOST EXTENT OF 



ERRATICS IN ENGLAND SUCCESSIVE PERIODS OF JUNCTION AND SEPA- 

 RATION OF ENGLAND, IRELAND, AND THE CONTINENT TIME REQUIRED 



FOR THESE CHANGES PROBABLE CAUSES OF THE UPHEAVAL AND 



BUBSIDENCE OF THE EARTH'S CRUST ANTIQUITY OF MAN CONSIDERED 



IN RELATION TO THE AGE OF THE EXISTING FAUNA AND FLORA. 



Extinct Glaciers in Wales. 



ri^PIE considerable amount of vertical movement in opposite 

 ^ directions, which was suggested in the last chapter, as 

 affording the most probable explanation of the position of 

 some of the stratified and fossiliferous drifts of Scotland, 

 formed since the commencement of the glacial period, will 

 appear less startling, if it can be shown that independent 

 observations lead us to infer that a geographical revolution 

 of still greater magnitude accompanied the successive phases 

 of glaciation through which the Welsh mountains have passed. 

 That Wales was once an independent centre of the dis- 

 persion of erratic blocks, has long been acknowledged. Dr. 

 Buckland published in 1842 his reasons for believing that 

 the Snowdonian mountains in Caernarvonshii-e were formerly 



