TEE AGRICULTURAL JOURNAL. 



305 



crops of the lower members of the series, 

 the Dwyka conglomerate and black shales, 

 fringe the coast at intervals, [between 

 Isipiugo and Umgeui river mouth we 

 have the Durban basin, which I have 

 just described. Further to the north is 

 the edge of the basin which exists at 

 Tongaat and Umhlali, and some miles to 

 the north of the Tugela river mouth we 

 get the basin of the Umlalaas coal-field in 

 Zululand. These various outcrops of the 

 Ecca series, bounded inland by the out- 

 crop of the lower part of the Dwyka 

 conglomerate, may individually be por- 

 tions of isolated basins of Ecca strata, or 

 they may represent the denuded, iiTegular 

 edges of one large basin, the bulk of 

 which is still under the sea. The coal- 

 bearing portion of the Ecca series does 

 not extend farther inland than four miles 

 from the coast, except in the case of the 

 Umlalaas Coal field in Zululand. 



With regard to the Eluff itself and the 

 ridges which connect it with the main- 

 land, few rock outcrops occur, except at 

 the lighthouse end. Here the rocky bluff, 

 which faces the sea, consists of a much 

 eroded and weather-worn cliff of yellow 

 cakareous sandstones, showing remark- 

 ably good examples of false bedding, 

 which has been nude very apparent by 

 weathering. So far as I could discover, 

 they are entire'y unfossiliferous and 

 therefore tliere is no clue ^o 4ieir age. 

 They are, however, ceitainly younger 

 than the Ecca, upon which they rest 

 unconformably. 



There are no rock exposures on the sand 

 covered connecting ridges, in fact, the 

 first outcrop is probal)ly this same rock 

 which occurs on the beach at Wentworth. 

 I believe it also occurs at Isipingo, while 

 It IS reported to be present to the west of 

 Clairmont quarry, wherf^ it rests upon the 

 Halaeoroic sandstones. At the northern 

 end of the Berea, above the Unigeni 

 quarry, there are evidences, in the alluvial 

 sands, of its having existed locallv, and 

 probably much of the nodular calcareous 

 material which occurs disseminated 

 through the surface sand, has been 

 derived from the denudation of this local 

 outlier of the Bluff rock. 



On the seaward face of the Bluff, a few 

 hundred yards south of the Cave Rock, 

 remains of a raised-beach occur, more 

 than twenty feet above the present high 



water mark. Its presence here has, no 

 doubt, been due to the calcareous nature 

 of the sandstones forming the Bluff. The 

 materials of which it cojisists have been 

 cemented together by the calcareous 

 matter derived from the sandstones. Very 

 little of the old beach now remains, 

 except small patches which have survived 

 denudation by the protection afforded 

 them, by their position, in the crevices 

 and cavities of the decomposad face 

 of the cliff. The contents of this 

 beach are chiefly oysters and other 

 mollusca which are probably of the 

 same species as those now living in 

 the neighbouring seas ; showing that this 

 elevation of the land, as exemplified by 

 the presence of the ancient raised beach, 

 so many feet above the present water 

 level, must have taken place within 

 geologically recent times. 



This raised beach has, however, another 

 and very important significance in re- 

 ference to the present subject. The 

 materials of which it consists are chiefly 

 coarse sand and a few well rounded 

 boulders, but mixed with them and 

 scattered through the mass occur num- 

 bers of small pebbles of black and grey 

 shales, which could only have been 

 derived from the rocks forming the bed 

 of the ocean to the south-east. These 

 are undoubtedly fragments of Ecca shales, 

 and their presence in this old shore 

 deposit, facing the ocean, goes a con- 

 siderable way to prove that some portion 

 of the Ecca series exists on the ocean bed 

 to the south-east of the Bluff. The in- 

 ference necessarily follows, that it is 

 probable that the Ecca series are con- 

 tinuous from the shale outcrop of the 

 Congella bore, underneath the allavials 

 of the Bay, and under the calcareous 

 sandstones of the Bluff. 



With refeience to the parallel drawn 

 by the miner Martin Nolan, in his letter, 

 between the formation around the Bluff 

 and the country around Sydney, from a 

 physical point of view there is none, 

 except that each possesses a harbour. 

 From a geological point of view there is 

 a certain analogy, but there are also some 

 very wide differences, as can be seen by 

 comparing the two sections on the 

 attached Diagram No. 1.* 



, '''^Mred to may he seen at the 



OJfice of the Suneyor-Ge7ieral. 



