I 



Upon coast lines have had little to do in the formation of such scenery as we 

 have visited to-day, or when we traverse the hills and vaUeys of the interior 

 of "Wales and Siluria. All marine denudation tends to form great plains. The 

 elevation of a few hundred feet would elevate our British straits into a nearly 

 horizontal plain, and further elevation would elevate them into table highlands. 

 I do not doubt that many of you must have been struck by the features of the 

 scenery among the "Welsh hills when standing upon some mountain top which 

 stretches away into a hill table land.^ Such are the old table lands of the Silurian 

 hills above the "Wells of Llanwrytyd, or the table lands that WDuld be so uniform 

 in this country were it not for the valleys cut into the land. 



I firmly believe that the ITpper Old Red Sandstone hills of Brecon and 

 Caermarthen are but fi'agments of an ancient sea bed, which once extended to 

 the Black Mountains, and thence over Radnorshire and Breconshire, a table-land 

 which was once the bed of the sea. These surfaces owe their origin to the 

 levelling power of the sea, and to after levelling by land ice, while the valleys 

 which intersect the hills have been cut out of the hills bj- floods produced by 

 melting snows, by ice, frost, and by rain and rivers, and other agents of subaerial 

 denudation. No doubt fractures and faults produced by earthquake movements 

 on the earth's crust have often determined the direction of many of the vales, 

 as does the fault which runs along the vale of Usk ; but there are many glens 

 where is no evidence of any fissure or fault, and where the once continuous 

 strata have been cut into by the erosive power of streams, rivers, and brooks 

 acting for long ages upon the emerged land. The old table-lands which you 

 see on ascending the hill country of "Wales and Siluria have been cut into a 

 regular network of interlacing vales. These vales generally owe their origin 

 to the effects of rain and springs, ice and snows, and have had nothing whatever 

 to do with the sea or the agencies of marine denudatioiu 



Much of the denudation of ancient surfaces has been attributed to erosioB 

 during the Glacial epoch, but I believe that the principal valleys in "Wales and 

 Siluria were excavated and channelled out in Pre-glacial times. There was a 

 long geological period which intervened between Pliocene times and the 

 iubmergence of Great Britain and much of Europe during the Glacial epoch, and 

 which we call the Pre-glacial period. It is called Pre-glacial in the sense that it 

 preceded those excessively cold periods during which the lands we now inhabit 

 were submerged beneath the glacial ocean, and preceded the intense cold that 

 set in diiring the maximum of the Glacial epoch. 



It was during the Preglacial period that England enjoyed a climate 

 siirdlar to present times, but somewhat colder, and when elephants, rhinoceri, 

 and other large animals lived in the old " Forests" of Norfolk (Forest of Cromer 

 period), and their remains were deposited with river shells and land plants, 

 the species of which are still in existence. This was a great Gontinental period. 

 The land was probably higher than now, and this country was joined to 

 France and Belgium. The cold went on increasing until it is not unlikely that 



K 2 



