348 Transactions. 



In general the writer sees no reason to depart from the opinion long held 

 by all New Zealand geologists that the amount of Pleistocene glaciation of 

 New Zealand did not attain to the magnitude of an ice-sheet. On the 

 western side of the South Island the ancient glaciers rea'^'hed the coast-lhie 

 in many places. On the eastern side they threaded far through the moun- 

 tain-valleys towards the coast. This result happens to be in harmony with 

 the descriptions that have been written in regard to the glaciation of Tas- 

 mania and Australia. 



Art. XLIV. — Botanical Evidence against the Recent Glaciation of New 



Zealand. 



By Geo. M. Thomson, F.L.S. 



[Read before the Otago Institute, 22nd September , 1909.] 



In his presidential address recently (11th May, 1909) delivered before our 

 Institute, Professor Park stated that " during the progress of his geological 

 work he had been fortunate enough to obtain evidence to show that New 

 Zealand, at one time had a glacial period similar to that of the Northern 

 Hemisphere. He had been able to prove that Otago and the greater part 

 of the South Island were covered with a continuous ice-sheet, probably an 

 extension of the South Polar ice.'' This glaciation occurred, according to 

 the President, in the Pleistocene period. 



It seemed to me, at first sight, impossible to explain many facts in con- 

 nection with the existing flora of New Zealand in face of such a pronounce- 

 ment, and I have accordingly sought to test the accuracy of this theory 

 from the botanical standpoint. Such evidence as is available seems to me 

 to be quite opposed to such a theory. 



Professor Park's claim means that the greater part of the South Island 

 (which, according to him, was only separated from the North Island in the 

 Pleistocene period) was at that time covered with an ice-sheet (exceeding 

 7.400 ft. in thickness in the Wakatipu basin) synchronous with that which 

 covered the Northern Hemisphere. To quote his own words as to the effects 

 of such an ice-sheet, " The forests were overAvhelmed and completely ob- 

 literated, the animals and men inhabiting . . . areas retreated before 

 the terrible blighting wall of ice. . . . The evidence that this mass 

 of ice had been all over Central Otago was so fresh that they might easily 

 imagine it had retreated only yesterday." 



There are three lines of botanical evidence which appear to me to dis- 

 prove a recent glacial epoch, as distinct from merely increased glaciation 

 due to elevation in the central regions. They are — (I) the occurrence in 

 the South Island and in the antarctic islands lying to the south of a re- 

 markably specialised group of genera and species, some of which range 

 into or are allied, to forins occurrino- in Australia and elsewhere, but not 



