152 TERTIARY ROCKS OF AUSTRALASIA, 



fossils. The localities where they are best known occur 

 at (1) a point a little to the south of Cape Grim, extending 

 to Welcome River ; (2) Table Cape ; (3) Heathy Valley, 

 Flinders' Island. 



No marine Tertiaries are known to exist northward 

 towards the Gulf of Carpentaria between the older forma- 

 tions of Western Australia and the Eastern Cordillera ; 

 and Mr. Tenison- Woods and other authorities state that 

 the Tertiaries thin out in the direction of the northern 

 and eastern tributaries of the Murray (Riverina District). 

 The ancient mesial gulf dividing the old land of Western 

 Australia from the Eastern Cordillera is in the northern 

 portion occupied mainly by marine formations of Cre- 

 taceous age. 



The lacustrine formations, also oi Palceogene age — con- 

 sisting of clays, marls, sands, lignites, leaf-beds, and pebble 

 drifts — occur in limited basins at various altitudes through- 

 out the eastern and southern part of Australia, and very 

 extensively throughout Tasmania, where some of them 

 are found probably over 1000 feet in thickness. It is 

 estimated that the lacustrine formation known as the 

 Launceston Tertiary Basin, in northern Tasmania, alone 

 covered an area of not less than 600 square miles. 



Volcanic Activity. 



One of the most remarkable features of the Tertiary 

 period throughout Australia and Tasmania marking the 

 close of the Palaeogene epoch is the eruption of extensive 

 sheets, flows, and accumulations of feldspar basalts, with 

 their associated tuffs. It is evident tKat great volcanic 

 activity prevailed generally at this time, especially in the 

 neighbourhood of ancient lakes, estuaries, and river 

 systems. Considerable areas in such places are covered 

 by repeated flows or sheets of basalt or scoriae — over- 

 whelming forests, and filling ancient valleys, lakes, estuaries, 

 and river beds. Great waste and erosion have occurred 

 since the period of volcanic activity, and the existing beds 

 of watercourses now generally found at a much lower 

 level are often cut deeply through the sedimentary basins 

 formed by lakes during the Tertiary period. 



In the main valleys occur raised alluvial flats, and on 

 the higher slopes ancient gravel terraces ; the latter fre- 

 quently overlying the basalts or basaltic tuffs. Where these 



