316 Transactions. — Geology. 



product and record of a glacial period in the Southern Hemi- 

 sphere ? 



The gravels themselves, so far as I am acquainted with 

 them, contain no evidence of even the proximity of glaciers. 

 It seems,- however, difficult to believe that an area in w'hich 

 was produced such a massive record of frost-work could have 

 been far removed from a region where glaciers and ice-fields 

 existed at as low a level. In default of direct evidence on the 

 point, we could hardly doubt that the frosts which effected 

 such great denudation were much more severe than those 

 experienced in the same localities to-day. We may safely 

 assume that the eastern ranges, having been exposed to the 

 action of the sea as promontories or islands for a prolonged 

 period under a warm climate, had become extremely rugged 

 and precipitous, and that, consequently, when the frosts did 

 begin to work upon them, they w^ould do so under great advan- 

 tages. 



Still, such frosts as we now have, though working under 

 such favourable conditions, could hardly produce chips for 

 shingle-making in such quantities as to overload the streams 

 and compel them to lay out fans. There is, however, some 

 direct evidence in the gravels that, at a certain stage at all 

 events, the frosts were mu.ch more severe than they now are. 

 In two or three of the beds of shingle, separated by clays, in 

 the Geraldine downs, there are numerous lumps of white silty 

 clay, so large, so irregular in shape, and so distributed among 

 the shingle, that their sizes, forms, and pell-mell positions can 

 only be explained by the supposition that they are pieces of 

 the bed of a lake or pool, picked up and transported by being 

 frozen to and buoyed up by thick ice, and were deposited 

 where they are by stranding or the loss of their buoys. There 

 are also numerous smaller rolled pieces, some of silt so inco- 

 herent — some even of coarse sand — that they could not have 

 withstood rolling along a shingle river-bed unless they were 

 cemented by ice. The larger pieces — some of them 6ft. long 

 by 2ft. thick — could not have been floated, ice-buoyed, through 

 the rough channels of the stream within the mountains ; they 

 must have been picked up below the goi'ges. In them, there- 

 fore, we have evidence of winters in the lowlands so severe 

 that they may well have been related to the existence of great 

 ice-fields and glaciers in the alpine regions and at lower levels 

 in the south of the island. 



As moraines and boulder-clays are perhaps the most trust- 

 worthy and most easily-recognized marks of glacier work, it is 

 desirable that search should be made for such deposits of the 

 red-gravel age, as indices of the extfent of the glaciation during 

 that age. Such indices might be hopefully looked' for in 

 Otago ; and it appears to me that one has been found there. 



