THE CRETACEOUS SYSTEM 



299 



in the cliffs on the banks of that river below Wolve 

 Kraal, in the Zwartkops Valley below Uitenhage, near 

 the Coega Eiver, and at some other places such as the 

 Grass Eidge east of the town of Uitenhage, the Bethels- 

 dorp Salt Pan and the Zwartkops Salt Pan. 



The whole area has not yet been worked out, but 

 from the collections made up to the present time there 

 seem to be no marked divisions 

 of the marine beds, differing in 

 their fossils. The lowest marine 

 beds visible near the Zwartkops 

 Eiver are clays with badly pre- 

 served shells of Nucula, Pecten, 

 Actceonina atherstoni, Bochianites, 

 Dentalium and other marine 

 mollusca ; these beds are ex- 

 posed in a clay-pit near the north 

 end of the Eawson Bridge, the 

 bridge over the Zwartkops 

 Eiver. Stow mentioned some 

 clay beds near the Salt Vlei, 



Port Elizabeth, containing Zamites and other plants asso- 

 ciated with marine shells ; these rocks probably belong 

 to the upper part of the Wood beds, like those at Dun- 

 brody, and may be older than the lowest marine clays 

 in the Zwartkops Valley. The bulk of the marine beds 

 consist of clays, sandy shales, inconstant sandstones, 

 and limestones, usually bluish-grey when freshly exposed, 

 but weathering with yellow and brown surfaces. The 

 limestones are often crowded with shells, and some 

 layers in the shales are composed almost entirely of the 



Cladophlebis browniana. 



Half natural size. 

 FIG. 25. Plant from the 

 Uitenhage series (Wood 

 beds) (from Seward). 



