48 PROF. J. W. GREGORY ON THE [Feb. IQC4, 



striated surfaces remain ; but the aspect of the ridge, from the 

 crags of conglomerate above Xorth Lyell, shows in places the vestiges 

 of glaciated contours. The southern slopes of Mount Sedgwick, and 

 the valley between that mountain and Mount Tyndall, also exhibit 

 well-developed glacial contours. 



V. The Origin of the King-River Glacier. 



The origin of the glaciers and the direction of their movement is 

 clearly indicated by the nature of the erratic blocks. The King 

 Valley, east of Mounts Lyell and Owen, practically separates two 

 distinct types of country. On the east is a district made up of 

 Silurian and Carboniferous rocks and Mesozoic diabases. West 

 of the King River the rocks consist of some ancient schists, probably 

 Archaean in age, some ' Middle Silurian ' slates, limestones, and 

 quartzites, and the Devonian conglomerates and sandstones of 

 the West-Coast Range. The only occurrence that I found of 

 Carboniferous rocks to the west of the King Valley is near Linda, 

 where there are a few narrow outcrops of black FenesteUa-shales, 

 on the floor of the Linda Valley. This bed has been preserved 

 there by having been faulted down among the conglomerates. The 

 only near occurrence of diabase west of the King River, with which 

 I am acquainted, is on the summit of Mount Sedgwick. As the 

 glacial deposits include abundant boulders of Carboniferous Lime- 

 stone and shales, of sandstones (which are probably from the 

 Silurian rocks), and of diabase, the glaciers probably came from 

 the east and north-east. In that direction lies the great Central 

 Plateau of Tasmania, of which the Eldon Range is an outlier. 



The upper portion of the King-River Valley consists of two 

 parts at right angles to each other. The uppermost part trends 

 east and west along the southern face of the Eldon Range : this 

 valley is continued westward by the broad valley, between Mounts 

 Sedgwick and Lyell, 1 until it opens out onto the peneplain of North- 

 western Tasmania. At the western end of the Eldon Range the 

 King River bends abruptly southward, w r hile a small tributary 

 comes in from the north, between the end of the Eldon Range and 

 Mount Sedgwick. 



The general evidence suggests that, during the time of this 

 giaciation, the Eldon Range and the Central Plateau formed the 

 collecting-ground of the glaciers. From this area the glaciers 

 flowed westward and south-westward. One glacier flowed down 

 the valley between Mount Tyndall and Mount Sedgwick : doubtless 

 it received tributary glaciers from those two peaks. A well- 

 marked terminal moraine round the western end of Lake Margaret 

 marks either the farthest westerly extension of the glacier, or one 

 of the stages in its retreat. 



1 The Upper King River probably flowed originally through the Sedgwick 

 Valley ; see my paper on ' Some Features in the Geographv of North- Western 

 Tasmania ' Proc. Eoy. Soc. Vict. n. s. vol. xvi (1903) pp. 180-81. 



