BY LOFTUS HILLS, M.B.E., M.SC. 117 



per mile. Its age is certainly Pre-glacial, but its relation to 

 the Tertiary basalts has not been satisfactorily demonstrated. 



The Central Plateau is clearly a horst as regards its 

 northern, western, and southern precipitous slopes, but re- 

 cent work by P. B. Nye, B.M.E,, has shown that the eastern 

 face is not a fault scarp, but is due to the upthrust of a huge 

 transgressive diabase mass. The work of this investigator 

 in the Midlands has demonstrated that the Midland plain is 

 not a rift valley, as maintained by E. C. Andrews and Dr. 

 Griffith Taylor, but that the diabase masses on either side 

 of this plain are in the approximate positions relatively to 

 the similar rock of the plain which they assumed when 

 originally intruded. It seems, therefore, that the horst must 

 embrace portion of the Eastern Highlands, since undoubted 

 block faulting occurs towards the East Coast. It is hoped 

 that the geological surveys of the East Coast ccal-fields at 

 present in progress v/ill definitely settle this question. 



A considerable amount of work has been done on the 

 problem of our Pleistocene glaciation, but as this is dealt 

 with in a special report by the Glacial Sub-committee, there 

 is no need to repeat a description of it. Suffice it to say, that 

 a number of glacial cirques have been located and described, 

 as well as lakes of glacial origin, and the maximum descent 

 of the glaciers determined to be 460 feet above present sea 

 level. 



Some advance has been made in our knowledge of the 

 Recent oscillations of sea-level on the North and West 

 Coasts, but we are far from being able to outline these with 

 any degree of accuracy. The work of E. C. Andrews, 

 Charles Hedley, and Fritz Noetling must be acknowledged 

 in this connection. 



HI. STRATIGRAPHICAL GEOLOGY. 

 ( 1 ) . Pre-Cambrian. 



Since the late W. H. Twelvetrees presented a summary 

 of our knowledge of Tasmanian Pre-Cambrian geology before 

 this Association in 1907, there has been some definite ad- 

 vance in our knowledge. This advance resulted mainly from 

 two exploratory journeys made in 1908 and 1909 by the late 

 W. K Twelvetrees, in conjunction with L. K. Ward, B.A., 

 B.E., on the route of the proposed Great Western Railway. 



In the description of these Pre-Cambrian rocks presented 

 by L. K. Ward, in a paper read before The Royal Society 

 of Tasmania in 1909, the age determination is based on the 



