41 



NOTES ON CEETAIN TEETIARY AND POST TER- 

 TIARY DEPOSITS 



On Elinders, Barren, Badger, and other Islands in 

 Bass' Straits, by Robert M. Johnston. 



[Bead 9th April, 1878.] 



SAND DUNES AND ELEVATED BEACHES. 



Hitherto the more recent shell deposits upon the islands of 

 Bass' Straits have been briefly referred to by various writers 

 as " elevated beaches." Strzelecki groups the following for- 

 mations under that head, viz. : — 



1. Formation at Lake King, Grippsland. 



2. Ditto between Cape Liptrap and Portland Bay. 



3. Green Island, Bass' Straits. (100 feet high.)' 



4. Formation, south-west point of Flinders' Island. 



5. Ditto, 10 miles south of Cape G-rim. (100 feet high.) 



6. Ditto at Table Cape. (70 feet high.) 



Mr. G-unn also refers to the " raised beaches " :— - 



7. At Hunter's Island, near Woolnorth, and several islands 

 in Bass' Straits. 



Recent investigations have shown, however, that most of 

 the formations thus alluded to are not, properly speaking, 

 '' raised sea beaches." They are, for the most part, the 

 remains of the floor of a vast but shallow sea of supposed 

 miocene or oligocene age. 



The Rev. J. E. Tenison- Woods, in a paper recently read 

 before the Fellows of the R.S. of New South Wales, states : — 



" To sum up all the evidence which has been gathered on 

 this subject, we may say that our tertiary formations pro- 

 bably range through all the various miocene periods which 

 are represented by different deposits on other portions of the 

 globe. We may certainly conclude that the whole of the 

 central j^arts of South Australia, the north of Tasmania, and 

 the islands of Bass' Straits, were luider the sea during that 

 epoch. There is cjuite sufficient evidence to show that we 

 have tertiary rocks of a lower horizon than the miocene. My 

 own oj^iuion is that the Muddy Creek beds, and those of 

 Table Cape, Tasmania, should be classed as upper oligocene. 

 I conclude this from the small per centage (8 per cent.) of 

 recent species, the relations of the fossils, and the general 

 facies." 



There is also abundant evidence to show that this ocean 

 floor has been slowly elevated above the level of the waters 

 in which it was formed ; and although this upward movement 

 may not have been miinterrupted in one locality, yet there is 



