24 NOTES ON MT. ANNE AND TUE WEI.D RIVER TALLEY, 



the form of sills. On the south-eastern shoulder of Mt. 

 Mueller basal conglomerates of the Permo-Carboniferous 

 appear at a height of at least 1,800 feet, while at Fitz- 

 gerald, six miles away, the top of the system can be seen 

 at an elevation of 900 feet. This points either to a diabase 

 uplift on the eastern slope of Mt. Mueller of at least 2,000 

 feet, or to a fault with a throw of that height running along 

 the face of Mt. INIueller. In view of what has occurred 

 Throughout Tasmania it seems more probable that the 

 diabase of Mt. Mueller has raised the tillite, with the quai'tzite 

 that underlies it, to their present height. The diabase of 

 Mt. Mueller appears to reach a low level on the north-eastern 

 slope, but it does not appear to be connected with the diabase 

 from the Mt. Field ranges, which extends westward in a 

 broad sill now seen capping Field West, Tyenna Peak, the 

 Knobs, and Wherrett's Look-Out. To the south-east the 

 diabase of the hills south of Tyenna approaches, if it does 

 not join, that of Mt. Mueller. To the west, the Mueller 

 diabase appears to have extended over the quartzites in a 

 sill in the direction of Mt. Wedge. 



Mt. Weld is certainly a diabase uplift. There are con- 

 siderable occurrences of diabase in the valley of the Weld 

 between 5 and 10 miles trom its mouth at a height under 

 300 feet above sea level, whence it appears to lead right to 

 the summit over 4,000 feet above. Alongside Fletcher's 

 Hut on the banks of the Weld the diabase can be seen 

 penetrating the quartzites in a large dyke of very close- 

 grained rock. To the west the diabase appears to extend 

 for some distance in a sill over the top of ths quartzites. 



Mt. Wedge is crowned with a cone of diabase, appar- 

 ently a portion of an old sill resting on the older quartzites. 

 but the writer has no data at present on which to determine 

 from which direction the sill originaMy came. 



Mt. Anne is also capped with diabase, probably por- 

 tion of ah old sill. It lies on top of the highly inclined 

 quartzites, and appears now to be 1,200-1,500 feet in thick- 

 ness. The most interesting feature of its occurrence here is 

 the existence on the top of the Mt. Anne plateau of a small 

 area of quartzite, perhaps a square mile in extent and 100 

 feet thick. This is an almost unique feature in the Tas- 

 manian occurrence of diabase. This mass of quartzite, 

 which appears to be a remnant of the rocks through which 

 the sill penetrated and which prabably originally overlaid 

 it, has either been lifted 1,500 feet from its bed by the intrud- 

 ing sill or has been sheared from the top of some mass of 

 quartzite and been carried along by the diabase. As the 



