BY L. KEITH WARD, B.A., B.E. 125 



I.— INTRO'DUCTIO'N. 



It may not be altogether inappropriate, in con- 

 tributing a paper on the systematic Geology of Tas- 

 mania, to commence at the bottom of the geological 

 column. 



In the following pages the writer has the honour to 

 present some portion of the information now available 

 concerning that great series of rocks which constitutes 

 the base of the geological record in Tasmania. 



There are several questions connected with these 

 rocks and their relations to the succeeding sediments 

 which cannot but be, in the present state of our know- 

 ledge, debatable. Yet it may now be confidently asserted 

 that these rocks are truly Pre-Cambrian in age ; and 

 this paper is largely concerned with the nature of the 

 evidence upon which this assertion is made. Hitherto 

 there has been a certain lack of definite information 

 available, and the accurate classification of the series 

 has been, in consequence, impossible of achievement. 



However, within the last year the work of the 

 Geological Survey stafif has taken Mr. W; H. Twelve- 

 trees and the writer into areas in which these funda- 

 mental rocks- are well developed, and in which some de- 

 tails of their relationships to other members of the 

 geological record are displayed. The geological ex- 

 ploration of the Great Western Railway route has pro- 

 vided material for an almost continuous section across 

 Tasmania from Gormanston to Tyenna ; and during 

 the progress of this work a fund of matter has accumu- 

 lated which is of inestimable value in the correlation of 

 the strata encountered. This information is here pre- 

 sented in so far as it concerns the Pre-Cambrian rocks ; 

 and in the light of these recent discoveries some account 

 is given of the deductions which may be drawn with 

 regard to the origin, growth, and decay of the Pre- 

 Cambrian rocks of Tasmania. 



