CHAP. xiv. EXTINCT GLACIERS IN WALES. 265 



CHAPTEE XIV. 



CHRONOLOGICAL RELATIONS OF THE GLACIAL PERIOD AND 

 THE EARLIEST SIGNS OF MAN'S APPEARANCE IN EUROPE, 



Continued. 



SIGNS OP EXTINCT GLACIERS IN WALES GEEAT SUBMERGENCE OP 

 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 OP 



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 



SUBSIDENCE OF THE EARTH* S CRUST ANTIQUITY OF MAN CONSIDERED 



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



Extinct Glaciers in Wales. 



considerable amount of vertical movement in opposite 

 J- directions, which was suggested in the last chapter, as 

 affording the most prohable 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 Caernarvonshire were formerly 



