39 



be submerged at high water to the extent of 6J ft. At Glan- 

 ville the same bed, if relieved of the overburden, would be 

 submerged at high water by about 25 ft. or 26 ft., which 

 difference can be easily accounted for by the gradual slope 

 of the old sea floor towards the west. In the Dry Creek 

 section, 12 ft. to 15 ft. of fresh-water sands and clays separate 

 the two marine deposits, while, at Glanville, the thickness 

 of the alluvial wedge amounts to 11 ft., if we recognize the 

 beach deposits as the base level of the upper marine bed, 

 and 26 ft. if we take the full thickness between the lower 

 marine and the fossiliferous estuarine clay at the top of the 

 section, which seems to be the same horizon as that repre- 

 sented in the upper marine at Dry Creek. 



At both Dry Creek and Glanville the lower marine bed 

 rests on alluvium. The next marine horizon below those 

 dealt with in this paper is that of the Lower Pliocene, proved 

 in the boring for water put down by the Australian Smelting 

 Company, at their works, at Dry Creek. ^) The site of the 

 bore was at the margin of the recent marine sites, 14 ft. 

 above sea-level. The Lower Pliocene marine sands were met 

 with at a depth of 320 ft., so that a period sufficiently long 

 to permit of the laying down of 300 ft. of alluvial material 

 must have intervened between the withdrawal of the Pliocene 

 sea and its return in Pleistocene times. It may be interesting 

 to point out that we now have evidences of five distinct recur- 

 rences of sea-intrusion in the neighbourhood of Adelaide, 

 viz. j Recent, Sub-Recent, Pliocene, Miocene, and Eocene, 

 each of which intrusions was separated from the others in the 

 succession by long periods of dry-land conditions. 



(4) Tate "On the Discovery of Marine Deposits of Pliocene 

 Age in Australia," Trans. Roy. Soc, S.A., vol. xiii., p. 172, 1890. 



