FERNS, FOSSILS AND FUEL 
It was supposed originally that the entire Karoo beds 
had been deposited by the great lakes and rivers draining 
the southern glacial ice caps, but recently others have 
compared them with the wind-borne deposits (loess) of 
the northern glacial epoch. The Karoo was undoubtedly 
a region in which the dust of the desert had been accumu¬ 
lated in large quantities by wind drifts. Similar sand 
deposits are formed nowadays in the deserts of South 
Africa, although the climate is warmer now than it was 
in the Permian period, because of the retreat of the 
extensive ice fields that existed then around the south pole. 
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