BY L. KEITH WARD, B.A., B.E. j^y 



VII.— THE DISTRIBUTION OF THE PRE- 

 CAMBRIAN IN TASMANIA. 



A map of Tasmania showing the several areas occu- 

 pied by Pre-Cambrian rocks has been prepared to ac- 

 company this paper. On this map the several areas are 

 numbered, and reference is here made to the different 

 districts in the order in which they have been numbered 

 on the map. 



I. The Asbestos Range area, lying to the west of 

 Beaconsfield, and extending southwards from the coast- 

 line at Badger Head, comprises a series of micaceous 

 schists, slates, and grits, with a strike of N. lodeg. W. 

 to N. 2odeg. W. (i). These rocks are bounded on the 

 east by serpentine and other igneous rocks in the 

 vicinity of Beaconsfield (2). On the coast-line recent 

 sands and drift overlap the Pre-Cambrian on both sides 

 of the range (3). 



The southward extension of this belt of schistose has 

 not yet been fully mapped. 



II. At Hamilton-on-Forth there is an exposure of the 

 Pre- Cambrian bedrock in the gorge of the Forth River. 

 The rocks represented are quartzites, quartz-mica, mica 

 ceous and graphitic schists, and with these a belt of 

 .garnetiferous-zoisite-amphibolite. 



The strike of the schistose sediments varies from N. 

 lodeg. W. to N. 3odeg. W., and they dip to the south- 

 west. 



This exposure is covered, save in the river gorge, by 

 Tertiary basalt ; and on being followed southwards is 

 found to disappear below the Cambrian formations (4). 



(i) See W. H. Twelvetrees' " Report on Coal near George 

 Town, and Slate near Badger Head," 1904. 



(2) See W. H. Twelvetrees' "Report: on the Mineral Re- 

 sources of the districts of Beaconsfield and Salisbury," 1903. 



(3) See T. Stephens' " Notes on the Geology of the North- 

 West Coast of Tasmania from the River Tamar to Circular 

 Head," Proc. Linnaean Soc. of New South Wales, 1908. 



(4) See W. H. Twelvetrees' " Report on the North-West 

 Coast Mineral Deposits," 1905. 



