156 president's address. — section c. 



instances where the Miocenes rest ou a Palaeozoic floor, it is possible 

 that the older marine beds had been entirely removed by denudation 

 before the sinking of the land that admitted the Miocene sediments. 



The Miocene beds make no prominent feature in the present 

 landscape. They occur, as a rule, coincidently with the older Cainozoic 

 marine beds, and supply the same physiographical features. 



UPPER CAINOZOIC (NEOGENE). 



Third Marine Series. — Older Pliocene. — The marine beds that were 

 determined by the late Professor Tate to be of lower Pliocene age do 

 not appear at the surface, and have been proved only in three borings. 

 The localities are situated near Adelaide, in a north and south direction, 

 and are comprehended in a lineal distance of 18 miles. The first to 

 be put down was at Dry Creek, at an elevation of 14 feet above sea.- 

 level. The beds were entered at a depth of 320 feet, and proved to 

 be 90 feet in thickness.* A second discovery of beds of this age was 

 made in sinking a bore at Croydon, 2^ miles west of Adelaide. The 

 surface is 56 feet above sea-level, and the fossiliferous Pliocene was 

 proved at a depth of 395 feet, and showed a thickness of 320 feet.f 

 Later, a third bore was put down, 1 mile from Smithfield, and about 

 18 miles north from the Croydon bore. The same fossiliferous bed 

 was proved at a depth of 315 feet, with 5 feet of dark-coloured fetid 

 mud resting on top. The greatest quantity of material from the bores 

 in question was obtained from the Dry Creek sinking, and is therefore 

 the most valuable for comparison. Professor Tate determined 60 

 species from this material, of which 16 (or 27 per cent.) proved to 

 be recent forms ; 24 extinct species, common to the Eocene and Miocene 

 iauna ; and 20 restricted species. 



The stratigraphical relationship of this fossiliferous horizon are 

 somewhat obscure. The order of events that followed the close of the 

 Miocene submergence is difficult to trace. The palseontological evidence 

 requires that there should be, at least, as great an interval between the 



• The bore was stopped at this depth, but it is uncertain whether the base of the fossihferoua 

 beds was reached or not. It is not known what beds underlie these Pliocene sands. Tate " On 

 tha Discovery of Marine Deposits of Pliocene Age in Australia," Trans. Roy. Soc.S. Aus., Vol. XIII, 

 p. 172. 



t There appears to be a discrepancy in Tate's estimate of the thickmss of the fossiliferous 

 PUocene beds in relation to the two bores put down at Croydon. In his first paper, dealing with 

 No. 1 Bore (Ibid., Vol. XIII, p. 183). he says," The great thickness of the Older Pliocene, 406 feet 

 -at the least, is unexpected, as I had conjectured that its base was near-approached in the Dry Oreek 

 bore, at a level corresponding with the superior beds only parsed througli in the Uroydon bore ; 

 but, admitting the correctness of the assumption, then "the new facts simply indicate a great 

 inequality of the floor on which the Older Pliocene deposits have accumulated." Tate, in a 

 subsequent paper dealing with the Croydon Bore No. 2, states tliat in Bore No. 1 the fossiliferous 

 development of the Older Pliocene extended from the 395-feet to 605 feet (= 210 feet), while in 

 his summary of the strata in No. 2 Bore, which was put down close to No. 1 Bore, he gave the 

 thickness of the fossiliferous Pliocene as 320 feet. Ibid, Vol. XXII, pp. 194, 196. 



