Park. — The Great Ice Age of Neiv Zealand. 593 



I have described the Taieri glacial deposit as a ground-moraine, as 

 opposed to the view that it is a terminal moraine. Dr. Marshall* chal- 

 lenges this conclusion, asserting that a boulder-clay or ground-moraine is 

 relatively thin because formed between the ice and the bed-rock, whereas 

 the Taieri Moraine is, he says, at least 700 ft. thick. In making this state- 

 ment he would seem to have fallen into an error. The thickness of 

 boulder-clays, as recorded by eminent geologists, proves conclusively that 

 such deposits are not relatively thin, but, on the contrary, relatively thick. 



The till of Scotland, according to Sir Archibald Geikie, varies from 

 to 160 ft. thick ; and that of North America, f according to Professor Salis- 

 bury, from to 500 ft. At Back Valley, in South Australia,^ the Com- 

 mittee on Glaciation of the Australasian Association for the Advancement 

 of Science reports a Permo-Carboniferous glacial drift or till 1,500 ft. thick. 

 In Germany§ the Pleistocene glacial drift varies from to 670 ft. thick. 



In Greenland, II Geikie tells us, " Nansen found enormous accumulations 

 of ground-moraine on the edge of the inland ice at Austmannatjern, where 

 there were no nunataks, and not a vestige of surface moraine was visible." 



The Cambrian glacial beds of South Australia are described by Mr. W. 

 Howchiniy as being 1,500 ft. thick in the gorge of Appila, including, to use 

 his own words, " 860 ft. of characteristic till with boulders." Thus we 

 find that from the earliest geological times up to the Pleistocene a glacial 

 till is not relatively thin, but may be many hundred feet thick. 



Professor Marshall also states that a boulder-clay is more or less con- 

 tinuous in its disposition over the whole area covered by the ice-sheet. 

 This statement also is at variance with known facts. In Scotland, which 

 was completely covered with the northern ice-sheet in the Glacial period, 

 the till is not only notoriously irregular, but it covers a relatively small 

 portion of the country. In writing of the unequal distribution of the 

 glacial drift, or till, in North America,** Professors ChamberUn and SaUs- 

 bury state that "The thickness of the drift ranges from zero to 500ft., 

 and the variations are often great within short distances. One hill may 

 be composed of drift, while the next has no more than an interrupted 

 mantle of drift. The drift may be thick on hills and thin in valleys, but 

 more commonly the reverse is the case." Irregularity is, without doubt, 

 one of the distinctive features of a glacial till. 



The Taieri Moraine reaches its northern limit south of Saddle Hill, but 

 small areas of glacial till occur, as first pointed out by Mr. J. T. Thomson,tt 

 in the Kaikorai Valley, more particularly at Fernhill Coal-mine, Abbots- 

 ford, and Burnside. The till consists for the most part of confused de- 

 posits of angular and semi-angular boulders of igneous rocks and clays, 

 generally unstratified ; but in some places the material is irregularly 

 bedded, as may be seen in the steep escarpment overlooking Fernhill Coal- 

 mine. 



The moraine at Abbotsford is a typical example of a glacial till. It 

 begins at Abbott's Saddle, overlooking the Taieri Plain, and extends from 



* P. Marshall, Otago Daily Times, 13th May, 1909. 



t Chambeiiiu and Salisbury, " Geology," vol. iii, p. 340. 



X Proc. A.A.A.S., vol. vii. p. 126; 1898. /^ 



§ A. Geikie, " Earth Sculpture," 1902, p. 191. /■"" ' 



II A. Geikie, I.e., p. 176. 



^ Walter Howchin, Trans. A.A.A.S., vol. xi, p. 266. ' 



** Chamberlin and Salisbury, " Geology," vol. iii, p. 346. ' 

 tt J. T. Thomson, Trans. N.Z. Inst., vol. vi, p. 313. 



