BY LOFTUS HILLS, M.B.E., M.SC. 143 



suit of definite surveys measure in all 2,122 square miles. 

 There, therefore, remain to be mapped 24,093 square miles. 

 This, it must be admitted, is a big task. 



In addition, it must be pointed out that the greater part 

 of those geological maps already prepared are approximate 

 only, and the more accurate survey of these areas is a pro- 

 blem for the future. 



(2). Physiography. 



(a). A more detailed description than anything at- 

 tempted heretofore of the topographic features of Tasmania 

 is a desideratum. A large amount of field work yet remains 

 to be done before such an account can be completed. Parti- 

 cularly does this apply to the south-western portion of the 

 Island. 



(b). The exact relationship between the more prominent 

 topographic features and geologic structure must be worked 

 out. Particularly does this apply to the problem of the re- 

 spective roles played by the diabasic upthrust, Tertiary ten- 

 sional faulting, and erosion in the evolution of our Diabase 

 Highlands. A similar problem confronts us in the origin 

 of those "inland seas," Macquarie Harbour and Port Davey, 

 as well as the D'Entrecasteaux Channel and the Derwent 

 Estuary. 



(c) Some of our highland lakes are of glacial origin, 

 but the problem of the origin of the greater number of our 

 lakes is still to be solved. 



(d). The evolution of the drainage system of Tasmania 

 has yet to be traced. Incidental to this is the problem point- 

 ed out by Dr. Griffith Taylor, in his "Australian Environ- 

 '"ment," of the pronounced bends in some of our largest 

 rivers. 



(e). The exact limits of the Darwin peneplain have 

 yet to be determined. Does it extend to the North-East and 

 East Coasts? What is its relation to the Tertiary tensional 

 faulting? 



(3). General Geology. 

 (a). The stratigraphy and structural geology of the 

 old sedimentary system at present termed Pre- Cambrian 

 yet remain uninvestigated in detail. This is undoubtedly an 

 undertaking of considerable magnitude, necessitating, as it 

 obviously will, explorations in uninhabited and heavily tim- 

 bered and mountainous country. Correlation of this rock 



