Thomson. — Glacial Action in Otago. 309 



referred to in the foregoing paper, and especially the part surrounding the 

 Spencer Mountains, presents features which, properly investigated, are 

 calculated to assist materially in solving many moot points in connection with 

 the action of glaciers. 



Art. LI. — On the Glacial Action and Terrace Formations of South New 

 Zealand, By J. T. Thomson, F.RG.S. 



(With Illustrations.) 

 [Read before the Otago Institute, Wth February, 1873.] 

 This paper is limited to the post-tertiary period, as will be seen by its 

 desiguation, and the remarks are drawn from occasional observations that 

 J have been able to make during these last seventeen years, while proceeding 

 over the country in various directions on official duty in connection with the 

 Survey Department. For the facts and figures availed of I am largely 

 indebted to the work of the officers of the survey staff, as set forth in the topo- 

 graphical maps. As I have always been engaged in duties which claimed atten- 

 tion before the subject in hand, I bring forward my results as those of an 

 occasional, and not those of a regular, observer. Much as I have travelled 

 over this part of New Zealand, I have seldom had time to diverge from the 

 trodden path to follow up or trace formations ; my essay can, therefore, be at 

 best incomplete, but if it induces those who have more learning and leisure at 

 their command to pursue the enquiry, the time of this meeting taken up in 

 listening to me will, then, at all events, not be entirely lost. 



We live here, at this epoch, in what we settlers from the British Islands 

 call the most agreeable temperature of the temperate zone, our annual mean 

 being that of Devonshire, England. That the temperature should ever have 

 been different, probably the earnest money-seekers of our fellow colonists have 

 never enquired. To the members of this Society, who are lovers of science by 

 natural bias, and who spend much of their time in seeking knowledge for its 

 sake only, the question, if it has not arisen to their minds before this, will 

 now interest them. 



In the older formations abxmdant proof is to be obtained of the gi'eat 

 alternations of heat and cold to which this world was subjected, information 

 on which point is to be obtained from the works of Lyell, Ansted, and others. 

 To notice these would be to take us out of the limits of the present theme, 

 and to hold to it we must consider the old geological periods to have passed — 

 to have performed their functions, as it were, in raising the mountains and 



