32 



a bed of white sand about 15 ft. in thickness, very full of 

 fossils — Venus, Pectens, Oysters, Pholas, small Gastropods, 

 Polyzoa, Coral, and the usual accumulations of a sea beach are 

 present in great profusion. The lower nine feet of this bed, 

 (as also the upper part in a less degree), is laminated with 

 thin bands of decomposed sea-weed running in lines which 

 maintain their regularity for considerable distances. This bed 

 is an undoubted beach formation. The shells are not in situ, 

 but are irregularly heaped and sorted by wave action, whilst 

 the sea-weed is spread out in thin layers, the fronds of the 

 latter being much broken and matted together. Several pieces 

 of wood were found in this bed, one being the trunk of a tree 

 about six feet in length and about six inches in diameter. When 

 this littoral deposit was in course of formation, the present 

 barrier of sand-hills which lines the coast did not exist, and the 

 open sea flowed over what is now Port Adelaide and the low- 

 lying ground in its vicinity. 



No. 5. Underlying the above-mentioned beach deposit is a very 

 interesting bed of sandy clay, which, in the aggregate, measures 

 about eleven or twelve feet in thickness. This clay, in its 

 upper part, is of a dark blue colour passing into drab and 

 reddish-brown hues in the lower portions. These colours do 

 not mark divisional lines in the strata, but follow a very 

 irregular course throughout the bed, the differences in colour 

 apparently arising from the more pervious portions of the clay 

 admitting"^ the percolation of water, Avhich has given the lower 

 parts more or less a reddish colour. Immediately at the 

 base of this bed of clay, and resting on the limestone crust, is a 

 layer of coarse red sand a few inches in thickness and is the 

 main water stratum of the section. This bed of sandy-clay or 

 loam is peculiarly interesting from the somewhat anomalous 

 way in which the fossils it contains are arranged. These are 

 apparently limited to the upper three feet of the bed, and do 

 not occur in horizontal layers, but in vertical fissures and 

 pockets. These pockets of sand and shells are most common 

 at the upper limits, near the junction of the clay with the 

 beach deposit that overlies it, and they thin out to narrow lines 

 as they descend into the clay, dying out at about three feet 

 from its upper limits. I think it cannot be doubted that these 

 fossil remains are foreign to the clay in which they are enclosed, 

 and have consequently been derived. The vertical pipes in 

 which they occur have all the appearance of crevices filled with 

 the material from the overlying bed, the white sand and shells, 

 which are often slightly consolidated into stalactitic pipes, 

 showing on the face of the clay in striking contrast to the dark 

 blue colour of the bed in which they are found. Outside these 

 vertical strings of shells, the clay, on either side of them, was 



