180 Proceedings of tJie Royal Society of Victoria. 



The Queen River itself appears too small to have formed so 

 great a valley ; but it is clear that the river system in this part 

 of Tasmania, at no distant date, was arranged very differently 

 from its present plan. 



Between Mount Lyell and Mount Sedgwick in the north there 

 is a deep valley. It is known as the Sedgwick Valley, and is two 

 miles in breadth. Though the walls on both sides are steep, 

 they have been cut back into deep gullies, between which are 

 long rocky spurs, so that the Sedgwick Valley shows signs of 

 much greater age than the canyon of the King River. This 

 Sedgwick Valley is a direct continuation of the north-eastern 

 branch of the King River, which drains the southern slope of 

 the Eldon Range. The valley to the Henty pene-plain opens by 

 a low pass known as the Sedgwick Gap. This Gap, now 1160 

 feet above sea level, is but slightly raised above the King River, 

 at its bend to the east of the Gap. In all probability the King 

 River once continued its westward course along the Sedgwick 

 Valley, through the Gap, and across the site of the Henty 

 pene-plain to the south of Crown Hill and the Professor. 

 This river would have been of considerable size and quite suffi- 

 cient to have formed the pene-plain. Then, either the glacier 

 which formerly tilled the valleys of the King River and some of 

 its tributaries, or a slight uplift along the Great Fault of Mount 

 Lyell — which runs along the western face of Mounts Sedgwick, 

 Lyell and Owen — interrupted the course of the King River. 

 The river was dammed back till it found a fresh outlet to the 

 south of Mount Owen, through the gap between Mounts Huxley 

 and Jukes. There it has cut for itself the deep canyon, through 

 wl)ich it flows to Macquarie Harbour. 



One important point in connection with the age of the pene- 

 plain and the deflection of the King River is its bearing on the 

 age of the recent glacial deposits of Tasmania. It has often been 

 maintained that extensive glaciations are the result of increased 

 elevation ; and this explanation is attractively simple because, if 

 a country be uplifted, its temperature must be reduced ; and, 

 therefore, if the precipitation remain the same, its snowfall will 

 be increased. The explanation, however, does not appear to be 

 consistent with the facts in some cases, where there is a consider- 

 able amount of evidence as to the relations of maximum glacia- 



