BY R, M. JOHNSTON, F.L.S. 153 



formations (Neogene) overlie the older granites, porphyries, 

 metamorphic rocks or slates, they are often mined in search 

 of auriferous and stanniferous drifts, which are generally 

 found occupying the " leads " of the ancient watercourses. 

 The outbursts of volcanic matter are not confined to the 

 lower plains and valleys, for many extensive patches are 

 found in Tasmania, in the great inland plateau, at a 

 height of from 3000 to 4000 feet above sea level, notably 

 at Lake St. Clair, Great Lake, Lake Sorell, and Marl- 

 borough. The western elevated plateau of Tasmania, in 

 the neighbourhood of Magnet Range, Mount Bischoff, 

 and Hampshire Hills, is covered to a great extent by a 

 considerable thickness of basalt, and in the localities named 

 this rock is found at altitudes varying between 1 800 and 

 2500 feet above sea level. 



Even in these higher levels the existence of extensive 

 underlying beds of lignite and ligneous clays with asso- 

 ciated leaf-beds, indicate that the outbursts occurred in 

 regions occupied by fresh-water lakes. 



Climate. 



Palceogene Period. — Professor Duncan is of opinion 

 that the evidence of the flora of the period resembles that 

 of tropical rather than extra- tropical Australia ; and that 

 the Echinodermata of the period afford similar evidence. 

 In addition, the marine beds' at Table Cape, Tasmania — 

 rich in reef-building corals — have recently afforded evi- 

 dence of contemporaneous relationship with a flora, some 

 of the species of which (Sapotacites oligoneuris, &c.) are 

 identical with those abounding in lacustrine deposits 

 throughout the island. Of the Tasmanian reef-building 

 corals Professor Duncan writes : " Evidently the reefs 

 round Tasmania, now long extinct, existed amidst all the 

 physical conditions pecuhar to coral growth on a large 

 scale. Puio sea water, in rapid movement, and having a 

 temperature of not less than 74° Fahrenheit, was as neces- 

 sary to them as it is to those far away to the north and 

 the north-east at the present day. The coral-isotherm 

 would have to be 1 5° of latitude south of its present posi- 

 tion in order that the reef should flourish south of Cape 

 Howe." 



We must not forget, however, that the Rev. J. Tenison- 



