632 GEOLOGY. 



In other parts of the world the Permian is widely developed. In 

 countries about the Indian Ocean, including South Asia, Australia, 

 and southern Africa, there is usually a less distinct break between 

 the Carboniferous and the Triassic systems than in Europe, and, locally 

 at least, the Permian seems to completely bridge the interval. 



Australia. — In South Australia, above a series of Coal Measures 

 the plants of which are of the normal Carboniferous types, there is 

 a series of marine beds alternating with beds which contain land plants 

 unlike those of the Coal Measures below. Considerable beds of coal 

 are also included in the series. Inter stratified with these marine 

 strata and coal seams there are considerable beds of conglomerate 

 of distinctive glacial type (Fig. 291). Some of the bowlders of the 

 conglomerate are striated in such a way as to leave no doubt as to 

 their glacier origin. Furthermore, the substratum on which the 

 bowlder beds rest has been repeatedly observed to be grooved: and 

 polished, like roches moutonnees, and the direction in which the ice 

 moved has been determined in more than one locality. Unwilling 

 as geologists were to believe that there was a glacial period at. this 

 early stage of the earth's history, the evidence now in hand is over- 

 whelming, and a glacial period in Australia in the late Carboniferous 

 or Permian period must be regarded as a demonstrated fact. 1 



The number of well-defined bowlder beds is in places (Bacchus 

 Mailsh District, Victoria) not less than nine or ten, and some of them 

 have a thickness of fully 200 feet. The marine beds with which they 

 are intercalated have an aggregate thickness of 2000 feet or more, 2 

 and 30 to 40 feet of coal are included between the highest and low- 

 est of the bowlder beds. The recurrence of the bowlder beds points 

 to the repeated recurrence of glacial conditions, and the great thick- 

 ness both of clastic beds and of the included coal point to the great 

 duration of the period through which the several glacial epochs were 

 distributed. 



These remarkable phenomena are not local. Counting Tasmania, 

 where glacial deposits are also found, the Paleozoic glaciation of 

 Australia had a known range of nearly 22° in latitude (42° in Tas- 



1 W. E. David, Q. J. G. S., Vol. LII, 1896, p. 289-301. " Glacial Action in Australia 

 in Permo-Carboniferous Time." Contains also references to all the literature on 

 the subject. 



2 Geikie gives 3500 feet, op. cit., p. 1060. 



