THE PERMIAN PERIOD. 



637 



accurately determined, but in the former it is known to have extended 

 from latitude 18° to about 35°, and probably still farther north, while 

 in the latter it is known to have extended from latitude 21° to 35°. 

 In an equatorial zone about 40° in width, glaciation has not been dis- 

 covered. The glaciation of these various countries has a range of 

 about 130° in longitude. Glacial conditions must, therefore, have 

 prevailed over an area, or at least about the borders of an area many 

 times as large as that covered by ice in the northern hemisphere during 

 the Pleistocene glacial period. 



The marked likeness of the floras associated with the glacial deposits 















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Fig. 292a. 



-North slopes of roches moutonnees. Near Prieska, South Africa, 

 rock surface shows glacial striae. (Schwarz.) 



The 



throughout these three continents is believed to be evidence that there 

 was land connection between them at the time of the glaciation. The 

 horizons to which the Carboniferous types of plants are restricted, 

 especially in Australia, have been thought to represent a lesser interval 

 of time than that occupied in the deposition of the Carboniferous beds 

 of Europe and America. Partly on this ground, the plant-bearing 

 beds associated with the glacial deposits in Australia, and containing 

 the Glossopteris flora, have been believed to represent the later part 

 of the Carboniferous period; and if so, they indicate that the plant- 

 life of this region advanced more rapidly than that of Europe and 



