162 A Physical Description 



conclusion as to the age of the rocks can be formed, except 

 that they are tertiary. Of that we may be certain — first, 

 because at Table Cape they overlie marine tertiary beds of 

 miocene age ; secondly, because at Breadalbane some beds 

 overflow plant remains, which are tertiary, and identified by 

 some of the plants with pliocene vegetable remains in Vic- 

 toria and New South Wales. These two outbursts must be 

 of different age, because the Table Cape beds have flowed 

 over the bottom of the sea, which has since been upheaved ; 

 but those of Breadalbane have flowed later, over dry land. 



No crater remains to show the points of ejection. It does 

 not take long to destroy such records, but we may conclude 

 at least that there has been no volcanic activity in very 

 recent times in Tasmania, such as we know existed in 

 Western Victoria or the south-eastern district of South 

 Australia, where several craters are still visible. The more 

 westerly they are situated the more recent in character they 

 become. The one most to the westward is quite modern. 



The tertiary marine beds at Table Cape form a small 

 patch of fossiliferous strata which owe their preservation 

 entirely to the capping of basaltic lava. Probably similar 

 patches are to be found under the basalt on the north coast. 

 At Breadalbane, miocene fossils are sometimes found in 

 wells. The formation is part of the great tertiary deposits 

 of Southern Australia, which extends with occasional 

 interruption over 20° of latitude and 10° of longitude. It 

 consists at Table Cape of bands of limestone, marl, and 

 clays, the latter often ferruginous and containing gravel, as 

 if the beds had been derived from decomposing traps. The 

 fossils identified are : — Murex eyrei, Fusus meredithse, F. 

 roblini, F. johnstonii, F. tateana, F. transenna, Triton 

 abbotti, T. minimum, Buccinum fragile, Trophon fragile, 

 Coniinella lyrsecostata, C. cancellata, Thala marginata, 

 Nassa marginata, Terebra additoides, T. simplex, Cassis 

 sufflatus, Cassidaria reticulospira, Syrnola bifasciata, 

 Actseon scrobiculatus, Columbella oxleyi, C. caniozoica, 

 Pleurotoma johnstonii, P. paracantha, P. sandleroicles, P. 

 pullulascens, Ancillaria mucronata, Voluta hannafordii, V. 

 anticingulata, V. antiscalaris; V. weldii, V. macroptera, V. 

 granatina, V. maccoyi, Marginella wentworthi, M. strombi- 

 f oralis, M. octoplicata, C. platyryncha, C. gastroplax, C. 

 eximia, C. archeri, Trivia mimina, T. avellanoides, Daph- 

 rella columbelloides, D. tenuisculpta, D. gracillima, Man- 

 gelia gracillina, N. wintlei, N. vixumbilicata, N. polita, 



