CLIMATIC VARIATIONS GREGORY. 341 



ical time. Thus remnants of a series of glacial deposits, which are 

 probably pre-Cambrian, occur in a series of localities around the Arctic 

 Zone ; * fragments of this early, circum- Arctic glacial chain occur in 

 the north of Norway, as described by Keusch and Strahan ; ^ in Spits- 

 bergen ; '^ as some bowlder beds, the descriptions of which are sug- 

 gestive of glacial formation, on the Coppermine River, and in Labra- 

 dor, where, however, according to A. P. Low, they may be Cambrian ; 

 and finally on the northern coasts of Siberia, near the estuary of the 

 Lena. The Cambrian system contains an extensive series of glacial 

 deposits, discovered by Mr. Howchin,'' running north and south 

 through South Australia, between the latitudes of 32° and 35° S., 

 and as these Cambrian till are interstratified with marine rocks, they 

 were probably formed about sea level. 



The next proved glacial period is the Upper Carboniferous and 

 perhaps Permian, as proved by the glacial deposits of India, South 

 Africa, Australia, and South America. They were originally as- 

 signed, in Africa and Australia, to the Trias, and subsequently to the 

 Permian, and the Permian age of the South Africa glacial deposits is 

 still asserted by some geologists. But, according to Mr. Seward,'' the 

 glacial deposits at Yereniging — which, according to one theory, are 

 redeposited glacial matei'ial, and would, therefore, be the latest of 

 the South African glacial beds — are Upper Carboniferous, and 

 that is the age of the best known and most extensive of the glacial 

 deposits of southeastern Australia. The Upper Cretaceous has some 

 evidence of glaciation in the Northern Hemisphere, for the occur- 

 rence of drift ice is the most probable explanation of the bowlders 

 found in the British Chalk ; and Professor Garw^ood found a glaciated 

 pebble on Bunting Bluff, in Spitsbergen, in some conglomerates 

 Avhich are Upper Cretaceous or Lower Cenozoic.'' With the excep- 

 tion of such scraps of evidence, there is no convincing proof of low 

 level glacial action until we reach the Pleistocene. 



'^ J. W. (Jresory, Quart. Journ. Geo!. Soc, Vol. LIII, 1897, p. 155. 



''A. Straliau, "The raised beaches and glacial deposits of Varanger Fiord," 

 ibid., Vol. LIII. 1897. pp. 147-153. 



"The pre-Cambrian glacial bed in Spitsbergen was referred to by Nordensk- 

 jold. I accidentally rediscovered it at Fox Point, on Bell Sound, in 1890, and 

 sketched the best exposed section. (Quart. Journ. Geol. Soc. Vol. LIV. 1898, 

 p. 216.) 



'^ Brief reference to these Cambrian glacial deposits is given in ]Mr. W. How- 

 chin's paper, " The geology of the Mount Lofty ranges," Pt. I, Trans. Roy. Soc. 

 South Australia. Vol. XXVIII. 1904, pp. 2.59. 278. and PI. XLIII. 



''A. C. Seward, "Fossil floras of Cape Colony," Annals South Africa Mu- 

 seum, Vol. IV. Pt. I, 1903. p. 101. 



f Quart. Journ, Geol. Soc, Vol. LIV, 1S9S, p. 217. 



