518 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



that I have examined are: — the raised beach jtist mentioned, -which is 

 about half a mile from the river's mouth, and 40 or 50 feet above 

 the present sea-level ; on the south bank of the Zwartkops, near 

 Eawson's Bridge ; and along the banks of the creek and Perreira's 

 River, towards Cradocktown. No trace of these shell-beds is found 

 on the surrounding highlands. 



This formation is also found protruding through the red clay that 

 forms a portion of the flat, between the outlier marked No. 1 in the 

 section (fig. 4) near the Salt Vlei and the sandstone on the coast 

 near Port Elizabeth. See/and g cf in that section (p. 508). 



In each locality mentioned this deposit extends a considerable 

 distance. Thus it can be traced from a spot where it is exposed by 

 a cutting through the north bank of the creek, on the Grahamstown 

 Eoad, across the raised flat over which the road passes towards the 

 Zwartkops, until you reach the wide alluvial flats that extend from 

 the south side of the river. Again it stretches from the road men- 

 tioned to the sand-hills along the coast. This portion, however, is 

 covered with soil, thickly interspersed with shingle, mainly composed 

 of pebbles of quartzite, from the distant hills. Wherever any wild 

 animal has burrowed through the soil and shingle, or where any 

 excavation has been made, the shells of this deposit are almost in- 

 variably exposed to view. In like manner it evidently extends 

 towards Port Elizabeth — as it there again makes its appearance, as 

 indicated in the section alluded to (fig. 4). We must note that we 

 have here the shingly beds with the red clay superposed ; I shall have 

 again to refer to the last-named deposit. 



I have foimd the shells from these ancient shell-banks on the 

 coast near the mouth of the creek, evidently washed out and spread 

 over the surface. 



Eeturning to our first point of departure, we can trace the shell- 

 bed, exposed at intervals, along the banks of the creek and Eerreira's 

 River, towards Cradocktown, as before mentioned ; and, after passing 

 the mud-flats on the south side of the Zwartkops River, we find it 

 again, extending along the banks of the same for more than half a 

 mile. In this locality it was evidently at one time of much greater 

 extent than at present, and must have occupied the very course of 

 the present river ; but it is being rapidly worn away by the action 

 of the stream. 



In some parts (at the bridge) this deposit is nearly 30 feet thick. 

 It is composed principally of sand, the upper portion being inter- 

 laminated with bands of limestone. This is especially the case at 

 the western (or what was its inland and most sheltered) extremity. 

 In these bands are imbedded large quantities of shells. At this 

 spot a large and characteristic Panojoeea is found. It is generally 

 buried in the lower part of the stratum, and rather frequently with 

 both valves entire. This is the only bank in which I have found 

 this shell, with the exception of a solitary specimen in the raised 

 beach before mentioned. At the creek and the banks of Eerreira's 

 River, I have not found any indications of it. At this place (Rawson's 

 Bridge) a large Solen is also very plentiful, as well as a Mactra and 



