STOW SOUTH-AFRICAN GEOLOGY. 503 



Above the Modeler Drift (Ford). — The country for a distance of 

 some 10 miles in a straight line between McLoughlin's and Modder 

 Drift, on the Sundays River, I have not been able to examine ; but 

 from the Modder Drift, for several miles, to the krantzes (precipices) 

 below the Addo Drift, at Tunbridge's, three distinct fossiliferous 

 bands make their appearance at intervals — that is to say, wherever 

 the rocks are sufficiently exposed on the slopes of the hills that bound 

 the S,W. side of the river. 



Unfortunately, it is here the same as lower doAvn the river, and 

 the hill-sides are too much covered with debris and brushwood to 

 enable any one to make a very accurate survey of the intervening- 

 strata. The belts vary from 2 to upwards of 3 feet in thickness. 

 The lowermost, No 3 (see Section G, fig. 3), contains large numbers of 

 Trigonia Herzogii, young and adult) ; but Trigonia conocmxliformis 

 is more abundant, and appears to be the characteristic shell here. 

 Trigonia vau is often found, but it is far scarcer than those just 

 mentioned ; also Cgjarina rugidosa, Astarte Herzogii, and Ostrea. 



The middle band, No. 2, Section Gr, is composed of a fossi- 

 liferous rock that appears to be, as before alluded to, the equivalent 

 of the " Modiola- and If amites -zone" at McLoughlin's. At present, 

 however, I am not aware that any fragments of Hamites africanus 

 have yet been found in this locality. Only in this bed, and in 

 Nos. 6 & 7, at McLoughlin's, is Modiola Bainii found, as far as I 

 have been able to learn ; and the accompanying shells, much like 

 those found in the corresponding zone shown as No. 7, Section E, 

 are Ammonites suhanceps, Gastrochcena dominicalis (in fossil wood), 

 Alaria coronata ?, Gardita nucidoides ?, Astarte Pinchiniana ?, and 

 small specimens of Astarte, Gyprina ?, Psammohia ?, Ostrea. 



The differences are that, above the Modder Drift, this stratum, 

 No. 2, is much thicker than No. 7 at McLoughlin's Bluff, as it here 

 attains, in some parts, a thickness of 3 feet ; the rock also is of a 

 closer and harder texture, and of a more uniform grey colour, whilst 

 the black specks of carbonized matter which characterize the 

 "■ Hamites-zone" at McLoughlin's are, as far as I could observe, 

 entirely wanting, owing most probably to the sediment of whicli 

 this rock is composed having been deposited in deeper water. 

 This stratum makes its appearance, as 1 have said, at intervals, 

 wherever the mountain-side is sufficiently denuded of the superin- 

 cumbent soil: thus it is exposed a little above Modder Drift, 

 again in a kloof (gully) called by Drs. E-ubidge & Atherstone, from 

 the number of Ammonites they found there, " Ammonite Kloof," 

 and again some six miles above the Addo Drift, and beyond Com- 

 mando Kraal on the Sundays River. These indications therefore 

 enable us to trace this " Modiola-zone " from the bluff, in Section E, 

 to the last-named spot, a distance of upwards of fifteen or sixteen 

 miles. Other indications of this same bed may most probably 

 be found between these different and widely separated points ; 

 but the difficulties of making a thorough examination, as I have 

 previously explained, are very great, covered as many of the hills 

 are with dense entangled brushwood, while at the same time there 



