52 PROF. J. W. GREGORY ON THE [Feb. I904, 



examination of one section showed that the beds are true boulder- 

 clays : the clay is tough, hard, and fine ; the boulders range up to 

 2 feet in longest diameter, and lie at all angles in the fine clay. 

 The shape of the boulders is characteristic of ice-action, most of them 

 having one or more flattened surfaces. The boulders, however, 

 are so decomposed that I could not find any indubitable glacial 

 scratches ; and they are so soft, that I could dig into them with 

 the hammer. They include boulders of Devonian conglomerates 

 and diabase, indicating a mixture of materials. There is no out- 

 crop of diabase in the immediate neighbourhood. 



The boulder-clay at this locality consists of a series of patches ; 

 remnants, no doubt, of a formerly-extensive sheet. This fact, coupled 

 with the extreme decomposition of the boulders, indicates a great age 

 for this material. Moreover, there is no indication of recent 

 glacial action in this locality. Therefore, although the evidence is 

 inconclusive, these boulder-clays may be provisionally 

 correlated with the Carboniferous Series ; and the 

 boulder-clays of the Pieman Valley give the lowest 

 level (400 feet above the sea) yet proved for the 

 Tasmanian Pleistocene glaciers. It must be remembered, 

 however, that there is certain evidence of a recent uplift of this 

 part of Tasmania to the height of several hundred feet, so that 

 some of the glaciers may have actually reached sea-level. 



VII. The Age of the Glaciatiox. 



The only direct evidence as to the latest date at which the glacial 

 deposits of North- Western Tasmania were formed is derived from 

 their condition of preservation. Mr. Dunn has remarked on the very 

 recent aspect of some of the rock-scorings, and many of the glacial 

 deposits are but slightly worn and weathered. The moraine in the 

 Linda Valley has been simply rounded off and cut through by the 

 Linda River ; the moraines around Lake Margaret are still in excel- 

 lent preservation. The deposits of the main King Valley have been 

 more denuded, for the river has widened that valley and removed 

 much of the old morainic material, except where it is preserved on 

 the flanks of Mount Lyell and Mount Owen. Some of the glacial 

 deposits, however, are little more altered than those of the North of 

 England, despite the heavy rainfall by which they are attacked. 

 And, so far as it is safe to judge the age of glacial deposits by their 

 condition of preservation, they may be as recent as some of the 

 later moraines of the North of England. 



The maximum age of the deposits is given by their strati- 

 graphical relations. They are not only later than the formation of 

 a great peneplain, which is one of the most conspicuous features 

 in North- Western Tasmania, but they were formed after the dissec- 

 tion of this peneplain had begun ; for some of the glacial deposits 

 in the valley of the Queen River at Queenstown are but little 

 above the present floor of the valley. 



