BY FRITZ NOETLING, M.A., Ph.D., ETC. 



237 



faunas east and west of that bridge, but that the two are 

 as separate as if the isthmus still existed. 



3. THE SUBMARINE TOPOGRAPHY OF BASS 

 STRAIT. 



Independently of Howitt, my own studies into the 

 civilisation of the Aborigines have led me to assume that 

 their immigration must have taken place at a time when 

 Tasmania and Australia were connected by a land bridge. 

 I went, however, somewhat further than Howitt, who 

 only constructed the 50 and 100 fathom line. I argued if 

 such a bridge existed, the submarine topography of Bass 

 Strait should reveal us its features provided we assume 

 that the sea level rose and water, covered previously 

 existing land. I consulted the Admiralty chart, which 

 contains a wonderful mass of information, and after a 

 good number of failures I succeeded in drawing the 

 isobathic lines from 5 to 5 fathoms. 



In order to fully understand the changes, we wih 

 begin with the appearance of Bass Strait at the present 

 day. We will then assume the sea level to subside to 

 the 20-fathom line, because the changes in the contour 

 between the o and 20 isobathe are very small. We will 

 then follow up the changes that take place when the sea 

 level gradually recedes to the 25, 30, 35, 40, 45, and 50 

 fathom line. 



(a) BASS STRAIT AT THE PRESENT DAY. 

 (PLATE I., FIG. I.) 



Bass Strait of the present day has a curious elliptical 

 form ; its longest axis runs almost due north-west to 

 south-east, and its length between Cape Otway and Cape 

 Portland is approximately 345 miles. The smaller axis 

 from Hunter's Island to Wilson's Promontory measures 



