35 



palseontological evidence. lu tlie upper bed, formed under 

 littoral conditions, all tlie examples are specifically identical 

 with those now inhabiting our Grulf, and which may be picked 

 up on our beach almost any day. In the lower marine bed, 

 represented by the stratum of calcareous sand and shells, all 

 the forms are recent and agree with known Australian shells, 

 but some of these (as has been pointed out by Prof. Tate), 

 such as Area trapezia and the large foraminifer Orhitolites 

 complanata, whilst found in the warmer seas of the Eastern 

 Coast have become extinct in the Grulf , where they formerly 

 existed in immense numbers. A consideration of habitat might 

 account for some of the differences noted in the fauna of the 

 respective beds, but it certainly does not explain the whole of 

 the ]3henomena. If, for example, O. complanata, which is ex- 

 tremely plentiful in the lower marine bed, existed in the Grulf 

 at the time when the upper marine bed was in course of forma- 

 tion, it is unaccountable that examples of this very conspicuous 

 foraminifer should not occur with the other remains in this 

 beach deposit, for in most cases where this form occurs in the 

 waters it is a marked feature in the local shore sands. 



Prom the reasons already detailed, I think there are strong 

 presumptive evidences, based on several collateral lines of proof, 

 that the Post-Tertiary beds of the seaboard do not represent a 

 regular succession of marine beds, but that there was a break 

 in the continuity of their deposition. In the view we have 

 taken, there is an older and a newer bed of recent marine, with 

 an intercalated formation of fresh-water origin dividing the 

 same, and connected with the fresh-water bed two horizons 

 representing dry-land conditions. In the section of the " New 

 Dock" shown in the Port Adelaide Museum, the white cal- 

 careous bed is represented as having been subjected to consider- 

 able denudation, gutters having been eroded in the bed to a 

 depth of more than half its thickness, and these subsequently 

 filled with the brown clay which is supposed in this paper to 

 be of fresh-water origin. Assuming this to be a correct 

 representation of the section, there could not be a stronger 

 confirmation of the theory of dry-land conditions at that 

 particular geological horizon. 



"What may underlie the lower marine bed is not very well 

 known. Mr. Pletcher informed the Pield Naturalists in their 

 visit to the section that below this calcareous bed there occurs 

 a bed of loose sand 10 ft. in thickness, and in proof of this he 

 pushed a rod down for about that depth without much difficulty. 

 Subsequent examination has shown that this bed is a loose 

 argillaceous sand, of a brownish colour, the included sand grains 

 being both large and angular. Under this bed of argillaceous 

 sand, in the judgment of Mr. Pletcher, another limestone crust 

 is supposed to occur. 



