48 TnUim<jtlon--<. 



Vosges glaciers. .3d, Mauy of them are liiglily polished, aud 

 others are grooved aud finely striated like tiie stones of ex- 

 isting Alpine glaciers, and, like those of a more ancient date, 

 scattered over various parts of the world, -ith, A hardened 

 cementing mass of red marl, in which the stones are very 

 thickly scattered, and which in some respects may be com- 

 pared to a Red Boulder Clay, in so far that both contain 

 angular, flattened, and striated stones, such as form the 

 breccias wherever they occur. The contained fragments are 

 all derived from the district, although some of them can be 

 shown to have travelled a distance of 30 miles. Here, then, 

 we have evidence of the most positive nature, taken from 

 our own district as well as the south of England, which points 

 most conclusively to the existence of glacial conditions at the 

 very time when this Permian Basin must have been pro- 

 duced. 



(c) Configuration of the Land Favourable. 

 The next question to be considered is whether the con- 

 figuration of the land was favourable for the accumulation 

 and descent of a mass of ice by the erosive action of which 

 the Permian Rock Basin we are considering might have been 

 produced. To trace out this question satisfactorily we must 

 transfer ourselves in thought away back to the Devonian 

 Epoch. It is very easily demonstrable that during the earlier 

 parts of this era the great stretch of Silurian strata, which 

 extends over most of the southern counties of Scotland, sank 

 deep into the bowels of the earth, from which it was re-ele- 

 vated in a vastly altered condition. Its half shaly beds 

 had been subjected to metamorphosing agents by which 

 they were changed into gi-eywacke ; and its former horizontal 

 lines of stratification had been bent and contorted by pressure, 

 and were now generally standing vertically. Immediately 

 after its re-elevation it must have been subjected to an enor- 

 mous amount of denudation, which resulted in the fomaation 

 of all the gi-eat valleys that now exist in the surrounding 

 counties ; ia fact, all the great natural featuies of the South 



