THE CAUSE OF THE GLACIAL PERIOD. 485 



has almost entirely vanished, and now, in Britain at all events, 

 it is little if at all attended to, and other glacial episodes in the 

 history of the world have continued to be brought forward and 

 are no longer looked upon as mere ill-judged conjectures. 



The same kind of brecciated bowlder-beds that are found in 

 our Permian strata occur in the Rotheliegende of Germany, 

 which I have visited in several places, and I believe them to 

 have had a like glacial origin. 



Mr. G. W. Stow, of the Orange Free State, has of late years 

 given most elaborate accounts of similar Permian bowlder-beds 

 in South Africa. There great masses of moraine matter not 

 only contain ice-scratched stones, but on the banks of rivers 

 where the Permian rock has been removed by aqueous denuda- 

 tion the underlying rocks, well rounded and mammillated, are 

 covered by deeply incised glacier grooves pointing in a direction 

 which at length leads the observer to the pre-Permian mount- 

 ains whence the stones were derived that formed these ancient 

 moraines. 



Messrs. Blanford and Medlicott have also given, in " The 

 Geology of India," an account of bowlder-beds in what they 

 believe to be Permian strata, and which they compare with 

 those described by me in England many years before. There 

 the Talchir strata of the Gondwana group contain numerous 

 bowlders, many of them six feet in diameter, and in one in- 

 stance some of the Mocks were found to be polished and striated, 

 and the underlying Vindhyan rocks were similarly marked. 

 The authors also correlate these glacial phenomena with those 

 found in similar deposits in South Africa, discovered and de- 

 scribed by Mr. Stow. 



In the Olive group of the Salt range, described by the same 

 authors, there is a curious resemblance between a certain con- 

 glomerate "and that of the Talchir group of the Gondwana 

 system." This "Olive conglomerate" belongs to the Creta- 

 ceous series, and contains ice-transported erratic bowlders de- 

 rived from unknown rocks, one of which, a red granite, "is 

 polished and striated on three faces in so characteristic a man- 

 ner that very little doubt can exist of its having been trans- 

 ported by ice." One block of red granite at the Mayo salt- 

 mines of Khewra "is seven feet high and nineteen feet in cir- 



