86 Remarks on a Tertiary Deposit 



ment of rocks requisite. I have merely to give a few plain 

 facts, patent to the most superficial observer, and to draw 

 very intelligible inferences from them. If the paper should 

 appear incomplete, it is because I wish to do no more than 

 allude to details, the knowledge of which more competent 

 men may hereafter extend. 



The few fossiliferous rocks that South Australia possesses, 

 are all, with one exception, of the tertiary epoch. That one 

 exception is at Willunga, where the formation is clearly 

 silurian. None of the tertiary beds have been as yet de- 

 scribed, but their classification will not, I apprehend, be a 

 matter of much difficulty. As they are connected with my 

 subject, I will here indicate where they occur, as far as the 

 colony is at present known, beginning with the most recent. 

 All round the coast from Adelaide to Port Augusta, and from 

 the Coorong to the mouth of the Glenelg, shells of existing 

 species are found, loosely imbedded in sand or mud to some 

 distance above the sea level. Where the country is flat (as 

 near Guichen Bay), this is continued sometimes seventeen 

 miles from the shore. The sea has left this most recent 

 formation as the land has been slowly upheaved. Where the 

 deposit goes to any depth, the same shells are found imbedded 

 in limestone, and what would be thought a different bed, is 

 shown by the included fossils to be of the same geological 

 age. Immediately under this, at Adelaide, another very re- 

 cent bed, containing shells, is found. The inclosed testacea 

 are all species now existing near Adelaide, or on the adjacent 

 coast in a more northerly direction. They generally show a 

 more genial climate than that which obtains at present, but 

 as the deposit is a very small one, this difference may be 

 owing more to local circumstances than to any great variation 

 of the physical geography of the locality. Next to this again, 

 and immediately following, as far as I can ascertain, though 

 my researches are not sufficiently extensive to assert that no 

 other deposit intervenes, there occurs a quartzose limestone- 

 bed, whose extensive cross or diagonal stratification shows it 

 to have been deposited from a deep sea current. This con- 

 tains no fossils, at least such as can with certainty be deter- 

 mined. The next beds in succession, and the last as far as 

 we know, are the Mount Gambier deposits, which contain 

 shells, mostly of extinct species. It is not quite certain whe- 

 ther these latter should be called upper Eocene or lower Mio- 

 cene, but more extended investigation will, doubtless, prove 

 them to belong to the former. I say this because I have 



