STOW — SOTJTH-ArEICAlir GEOIOGT. 501 



being made. The existence of this Astarte- and Trigonia-hsiTid. seems 

 to point out that the position I have given to the sections (on the 

 Zwartkops) is the most probable one. 



The fossiliferoTis strata Nos. 6 & 7, in Section E (fig. 3), were evi- 

 dently deposited under very different circumstances from any of 

 the others ; and wherever the one I have styled the Modiola- and 

 Hamites-zone (No. 7) makes its appearance, it possesses the same 

 lithologieal character. I have given this name to it on account of 

 the numerous specimens of Modiola Bainii and fragments of the 

 Hamites afncanus found in it. In this locality (McLoughlin's Bluff) 

 this stratum is full of soimll fragments of carbonized wood, which 

 rub doTSTi to black powder under the finger. These minute frag- 

 ments seem to indicate that the sedimentary matter of which this 

 particular portion of the bed is composed, must have been the 

 deposit of some current of water laden with innumerable small 

 pieces of vegetable drift, such as we see washed up in the present 

 day on the seashore, after rains, near the mouths of small rivers. 



Some miles further up Sundays Eiver, where this bed is again 

 exposed, and where its thickness is much greater, these specks of 

 carbonized matter are wanting — an indication that this latter por- 

 tion was most probably deposited further off shore, or from a dif- 

 ferent direction; but I shall have again to allude to this in my 

 observations on the Upper Sundays River. The shells also of this 

 stratum are, with few exceptions, of a very different character from 

 those of the Astarte- and Trigonia-heis, the sheUs of the latter 

 being, for the most part, strong massive shells, fit to live along the 

 coasts of an open sea, whilst those found in the zones of which I 

 am now speaking are, most of them, thin and fragile. The rock 

 itself is of a much looser texture than the associated non-fossili- 

 ferous sandstones — while these latter, which intervene between this 

 bed and the tippermost layer, increase in friabUity as they ascend, 

 and show a considerable difference from the compact sandstones of the 

 Lower Zwartkops. The rock composing the Hamites-zone is patchy 

 ia colour, appearing in some places of a reddish sandy tint, but 

 more frequently grey. This was the bed (No. 7) in which the large, 

 coiled, broken fossil, thought to have been an Ancyloceras (?), was 

 discovered by Major (now Lieut.-Col.) Eocke. In no other, that 

 I am aware of, have Hamites africanus and Belemnites afncanus 

 been found : fragments of the former are here exceedingly abun- 

 dant; but the latter is rare. Modiola Bainii seems almost ex- 

 clusively confined to this stratum. Fragments of either Hamites 

 or Modiola, found in the debris of the neighbouring cliffs, are 

 always a sure indication of the close proximity of this band. The 

 principal shells characteristic of this zone, are : — Hamites africanus 

 (very numerous), Ancyloce7'as (?) (two specimens), Trigonia Gold- 

 fussi, Tr. conocardiformis (young), Crassatella complicata, Modiola 

 Bainii (numerous), Mytilus Stowianus, Mytilus Ruhidgei, Belemnites 

 africanus (rather scarce) ; also, I believe, Alaria coronata, and small 

 specimens of Astarte, Cyprina (?), Psammohia (?), and Ostrea (nar- 

 row, curved). 



