1.26 Mr. J. Croll on the Physical Cause of the 



But the existence of glaciers in such an early age is certainly in- 

 consistent with Prof. Frankland's theory, and in fact with every 

 possible theory based upon the principle of internal heat. 



Prof. Frankland accounts for the glaciers of the Permian 

 period as follows : — 



" I have already argued," he says, li that perpetual snow 

 would first tip the mountain peaks, and then slowly and gra- 

 dually descend to the sea-level. But it must be borne in mind 

 that during the whole of the pre-glacial period the atmo- 

 spheric precipitation was even greater than during that period, 

 and consequently wherever the land rose well above the snow- 

 line, glaciers, on a scale far surpassing any of the present time, 

 would be the inevitable consequence " *. 



But glaciers on the sides of elevated mountains will not ex- 

 plain the facts of the Permian breccia. These breccias afford 

 conclusive evidence that in that early age our British mountains 

 were not only covered with perpetual snow, but must have had 

 glaciers stretching into the sea, and breaking up and floating 

 away as icebergs in a manner similar to what we find occurring 

 in Greenland at the present day. We cannot do better than 

 state the matter in Prof. Ramsay's own words. 



" These breccias are chiefly formed of the moraine-matter of 

 glaciers, drifted and scattered in the Permian sea by the agency 

 of icebergs . . . They were therefore deposited in water with 

 considerable regularity, and, as we have seen, over a large area. 

 It is altogether unlikely that the stones were poured into the 

 sea by rivers in the manner in which some conglomerates are 

 formed on steep coasts where mountain-ridges nearly approach 

 the shore, 1st, because the fragments, being derived almost 

 exclusively from the Longmynd country, if the sea then washed 

 its old shores, no river-currents passing out to sea could carry 

 such large fragments from thirty to fifty miles beyond their 

 mouths and scatter them promiscuously along an ordinary sea- 

 bottom ; and, 2ndly, if the rivers merely passed from the Long- 

 mynd across a lower land to the sea, transporting stones and 

 blocks of various size, these would have been waterworn on 

 their passage seaward after the manner of all far-transported 

 river-gravels, whereas many of the stones are somewhat flat, like 

 slabs, and most of them have their edges but little rounded "f. 

 If we adopt the theory that the climate of our globe has been 

 gradually becoming colder during all past ages, in consequence 

 of the gradual diminution of the influence of internal heat, how 

 are we to account for the glaciers and icebergs of the Permian 



* Phil. Mag. for May 1864. 



t Journal of the Geological Society, vol* xi. p. 198. 



