48 Evidences of a Glacial Epoch from Kerguelens Land, 



There are some other interesting generalisations to be noted 

 in connection with the " Challenger's " Antarctic trip. It is 

 believed that in winter the sea to the south of 63° is 

 frozen over.* At all seasons of the year a thin wedge- 

 shaped layer of ice-cold water projects northwards to 54 

 deg. south, covered by a skin of warmer water. The thick- 

 ness of a single season's ice is believed to be about three 

 feet^-f- whereas in the Arctic it is six feet. The icebergs are 

 stratified horizontally, the oldest and lowest strata being 

 the thinnest, as the result of vertical compression and 

 horizontal expansion. But the ice possesses a fine cleavage 

 lamination,^ the faces of which lie at right angles to the 

 bedding. The enormous outward thrust operating from the 

 pole, squeezing the ice-sheet outwards at the rate of a quarter 

 of a mile per annum, will account for the cleavage, and its 

 occurrence under such circumstances affords geologists a 

 striking confirmation of the correctness of the theory which, 

 has been advanced to explain rock cleavage. 



Two important features of the Antarctic Ocean have 

 been brought to light. 



Firstly, the nature of the sea-bed changes as we go south- 

 wards. It is barred with different materials, which, dis- 

 posed in three concentric zones, encircle the polar regions, 

 and, similarly, the ocean water is banded with three distinct 

 micro-faunal regions, corresponding in their respective 

 positions with the series of deposits accumulating below. 

 Between 64 deg. and .QQ deg. S. we have the blue muds, 

 with pebbles and decomposed shales, which elsewhere 

 always indicate land proximity. In this deposit, then, we 

 have an unexpected testimony to the existence of a land 

 area around the Antarctic Pole. From 64 deg. to 58 deg. S. 

 the bottom consists of diatom ooze and a little mineral matter 

 derived from the overlyiug ocean, which supports enormous 

 swarms of diatoms and a smaller number of radiolarians. 



From 53 deg. to 47 deg. S globigerina ooze predominates,, 

 and north of 47 deg. south red clay with such deep-sea 

 deposits of whales' ear-bones, sharks' teeth, and manganese 

 nodules, as are indicative of clear still water.§ 



Singular testimony to a past cold epoch was found at two 

 stations in 38 deg. S, within the Pacific, in the shape of small 

 granite erratics found far from land. || 



* Eep. p. 418. t Eep. p. 430. % Eep. 432. 



§ Challenger Reports, p. 813. § Reports, p. 435. 



