STOW SOTTTH-AFRICAN GEOLOGY. 499 



Herzogii are rather frequent. The other shells are Gervillia dentata, 

 Pholadomya dominiccdis, Exogyra imbricata, Area Jonesii, and an 

 Ostrea. In the bed, marked No. 12, near the upper part of the bluff 

 (figs. 1 & 3) we find Exogyra imbricata verj abundant ; Astarte Her. 

 zogii and Pleuromya lutraria are numerous ; but of Astarte Longland- 

 siana only one specimen has been found, and one of Trigonia Oassiope. 

 The other fossils known to occur, in bed No, 13, are : — Area Jonesii, 

 Cucidlcea Kraussii, Pinna Atherstonei, Placunopsis subjurensis, Tri- 

 gonia ventricosa, T. conocardiformis, Ostrea, Pecten'?, Ammonites. 

 JSTo. 13 is about 50 feet above the level of the river, and No. 12 about 

 200 feet. The rocks in this section dip 2°-4° from the river in- 

 wards, and are surmounted by Pliocene (?) limestone. 



Upper* Ztvarthops River. Seetion oyi the Old Road. — Some miles 

 further up the river, on the old Grahamstown Eoad (fig. 1), above the 

 drift (ford) , another fossiliferous bed (No. 11 ) is exposed along the hill- 

 side and across the road, as shown in Section B (fig. 3), some hundred 

 feet above the river. The dip of the strata here, said by Dv. Ather- 

 stone to be about 8°, is inwards from the banks of the river. It is here 

 that Cucidlcea Kraussii is found more frequently than in any other of 

 the fossiliferous bands, together with Trigonia Herzogii, Astarte 

 Herzogii, and Pleuromya lutraria, all of which are very numerous, 

 and may be looked upon as the characteristic shells of this stratum. 

 The Cucullcea, especially, seems to have flourished at the time of the 

 formation of this bed, and must have grown to a large size, as its 

 fragments show. The other fossils are : — Pleuromya lutraria, Cero- 

 inya papyracea, Trigonia Herzogii, var,, T. conocardiformis, T. vau, 

 Exogyra imbricata, Pecten, Pinna, Patella. 



Section at Cuyler Manor. — Still further up the stream, near Cuyler 

 Manor (fig. 1), is another exposed portion of this formation. I have 

 not visited this locality myself; but Mr. Longlands, who examined 

 it in 1867, very kindly furnished me with the section shown in 

 Section C (fig. 3). 



In the stratum of friable sandstone, marked 10, lie found Ammo- 

 nites, and very numerous specimens of Trigonia Herzogii ; in fact 

 the latter abounds so much that it may be looked upon as the most 

 characteristic fossil of this section. He also found a few specimens 

 of Exogyra imbricata, and a few fragments of Trigonia conocardi- 

 formis and Pleuromya lutraria. 



RemarTcs. — As the whole of the Zwartkops strata dip inland, and 

 along the course of the river, which has a somewhat rapid fall to- 

 wards the sea, I think these circumstances tend to prove that 

 these fossiliferous bands, as shown in Sections A, B, & C (fig. 3), are 

 not one and the same stratum, but form ^parallel series, as is shown 

 (in an exaggerated form) in fig. 1. Thus the stratum No. 13, in 

 which. Astarte Bronnii abounds, must be the lowest ; the bed, No^ 12 

 atEocke's Bluff follows, with its multitudes of Exogyra; the Cuddkea- 

 bed on the old Grahamstown road is the next in succession j and, 



* The word "upper" here used in reference to the Zwartkops and Sunday* 

 Rivers does not indicate the highest parts of those rivers, but some portions tO' 

 wards the furthermost range of the Trigonia-beds traversed by them. — T. R. J. ■ 



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