THE GLACIAL PERIOD. 219 



would break up all along the sharp ridge, and the loose dibris, 

 falling upon the snow, would be slowly carried downward by 

 the movement of the ndvt. Vast quantities of dibris would 

 thus tend to collect at the base of the Eock, and when the snow 

 melted in summer, the rubbish, becoming saturated, would tend 

 to move forward en masse, bike the so-called " earth-glaciers " of 

 the Eocky Mountains. 1 Thus in time all the low grounds would 

 become more or less completely buried. 



Similar irregular masses and sheets of calcareous breccia 

 and loose angular dibris occur at low levels in other parts of 

 the Mediterranean region, as in Corsica, Malta, and Cyprus, which 

 are not now accumulating, but evidently belong to some past 

 period, when the subaerial forces acted with more intensity 

 than at present. Some of these have been attributed to de- 

 vastating torrents, others to violent inroads of the sea, just in 

 the same manner as it was formerly attempted to account for 

 the erratic phenomena of alpine regions and Northern Europe. 

 They deserve, however, to be reconsidered with the light which 

 recent advances in our knowledge of the Glacial Period have 

 thrown upon such questions. In the extremely interesting 

 account of the Maltese breccias given by Professor Leith 

 Adams, 2 we read of accumulations of great blocks, mixed with 

 angular dibris and fine loam, which it is difficult to believe can 

 be due to the action of occasional deluges such as he attributes 

 them to. When one remembers the limited drainage-area of 

 the island and the small height of the watershed, it is hard to 

 understand how torrents sufficiently powerful to sweep along 

 blocks " fully fifteen feet in circumference " could have origin- 

 ated in Malta, unless under very different conditions of climate. 

 It is quite possible, however, that when Malta formed part of 

 the Continent, it may have experienced winters as severe as 

 those which cloaked the slopes of Gibraltar with heavy snow. 



1 Hayden : Geological and Geographical Survey of Colorado, 1873, p. 46. The 

 phenomena observed by Mr. Maw and his fellow-travellers at the base of the great 

 escarpment of the Atlas, bear a strong resemblance to those of the Gibraltar 

 breccias. May not they have a similar origin ? 



a Notes of a Naturalist in the Nile Valley and Malta, 1870. 



