126 THE GEOLOGY OF TASMANIA— THE PRE-CAMBRIAN. 



II.— PREVIOUS LITERATURE. 



The rocks which are here treated of have been re- 

 ferred to in tlie earher Hterature which deals Avith the 

 Geology of Tasmania as " Pre-Cambrian " or " Ar- 

 chaean " ; but the reasons for which this provisional 

 classification has been adopted have been admitted to 

 be insufificient. 



A^r. R. M. Johnston has clearly stated (i) the lack 

 of the neoessar}^ evidence required before the " quartz- 

 ites and metamorphic rocks " of his Geological Table 

 (2) could be definitely referred to this position in the 

 column. 



More recently, in a paper read before the Austra- 

 lasian Association for the Advancement of Science (3), 

 Mr. W. H. Twelvetrees gave a brief account of " Prob- 

 able Pre-Cambrian Strata in Tasmania." In this paper 

 Mr. Twelvetrees has stated that the several occurrences 

 of c[uartzites, mica schists, and hornblendic schists are 

 to 'be referred to the Pre-Cambrian mainly on the 

 grounds that they are lithologically dissimilar from any 

 members of the Cambrian, Ordovician, or Silurian sys- 

 tems which are capable of more rigid classification. 



Since this paper was written the country between 

 Tyenna and Gormanston has been geologically ex- 

 plored, and the uncertainties and doubts have given 

 place to confident assertions based upon the newly- 

 acquired information. The increase of knowledge, also, 

 with regard to the stratigraphical position Of the early 

 Palaeozoic sediments of Tasmania, and the recent cor- 

 relation of these strata in different parts of the island 

 have assisted to no small degree in placing the classifi- 

 cation of the Pre-Cambrian on a firm basis. 



The departmental literature which deals with the 

 several districts in which these rocks are developed is 

 mentioned below, when reference is made to these 

 areas. 



(i) R. M. Johnston. Geology of Tasmania. 1888, p. 17. 



(2) Ibidem, p. 15. 



(3) Proceedings A.A.A.S.. Adelaide, 1907, p. 466. 



