QUATERNARY CLIMATE COMMITTEE. 247 



(iii) The occurrence of the Moa, a struthious bird, belonging 

 to a group usually associated with a dry climate, and 

 open steppe country, may perhaps be indicative of a dry 

 climate. This is no doubt a somewhat slender argimient 

 taken by itself, but in conjunction with others it may add 

 to their strength. 

 The evidence for a more humid climate succeeding this arid one 

 may be summarized as follows : — 



(i) Forests containing Totara (Podocarpus totara) flourished 

 formerly over wide areas on the eastern slopes of the 

 Southern Alps, in the Mackenzie country, and on the dry 

 plateaus of Central Otago, which are now practically 

 treeless. Totara is mesophytic in habit, and the forests 

 of which it was an important element grew on an area 

 which, according to the most conservative opinions as 

 to the limits of glaciation during Pleistocene times, must 

 have been swept clear of all vegetation. 



Under steppe conditions this tree could not have 

 obtained a footing on the denuded land, and much less 

 have formed a notable constituent of extensive forests. 

 The disappearance of these forests has been attributed 

 to bush fires, but this explanation is quite inadequate to 

 explain all the facts and the disappearance is more likely 

 due to the present modified steppe conditions which 

 succeeded the humid ones, although it cannot be denied 

 that fires lit by the Maoris and early settlers hastened 

 the disappearance of these forests. 



(ii) Peat bogs formed of Sphagnum, occurring in Central Otago, 

 with a rainfall as low in some places as 14 inches per year, 

 are difficult to account for, unless it be allowed that they 

 were established initially during a time when the atmo- 

 sphere was more humid, since it has been demonstrated 

 that the growth of Sphagmma is dependent on atmospheric 

 precipitation and not on the presence of ground water. 



(iii) The xerophytic plants of Canterbury and Otago show a 

 remarkable aptitude to take on a leafy habit when grown 

 in moist and sheltered situations. It has been suggested 

 to a member of the Commtitee by Dr. Cockayne that at 

 some previous period they were subject to moist conditions 

 during which their leaf-forming power was allowed to 

 revive after becoming more or less dormant or recessive 

 during an antecedent dry period, 



(iv) The Land Mollusca which are still under consideration, are, 

 according to Suter, of a wet climate type, and could not 

 have established themselves in Canterbury or Central 

 Otago under present conditions. 



