Br. Atherstone — On Diamonds at the Cape. 211 



dykes in many places have forced them np, and the sands both of a 

 white and red colour, are simply the debris from the breaking up 

 and wearing away of their burnt porjDhyries and burnt clays or 

 Porcellanite, which were formed originally through the volcanic heat 

 vitrifying these silicious clays. No other geological deposits are 

 visible, nothing but igneous and volcanic rocks, and the sands mainly 

 produced by their decomposition, and associated with these sands and 

 in the beds of the Orange and Vaal rivers are the characteristic Trap 

 minerals only — such as Zeolites, Natrolite, and sometimes Stilbite, 

 with small agates and geodes of chalcedony ; from the interior of 

 which geodes, but of larger dimensions, are derived the brilliant rock 

 crystals, of which thousands may be found, most of them rounded on 

 the edges, though some are perfectly iminjured, as the usual 

 hexagonal prism, sometimes with both terminal pyramids." Now I 

 am fortunately able personally to contradict this statement in toto, 

 for although I haA'^e not visited the Hopetown District, I have 

 examined the Cradock district, and the country between it and 

 Colesberg, and I have myself collected beautifully perfect reptilian 

 and other fossils from the very parts which Mr. Gregory declares to 

 be nothing but igneous and volcanic. " No other geological deposits 

 are visible," he states ! Dr. Gray, of Cradock, has sent home numbers 

 of Dicynodon and other fossils from this very district ; so have I and 

 Mr. Bain, Mr. Stowe, and others. If this is a specimen of Mr. 

 Gregory's careful and lengthened examination of the Cradock 

 division, we know what value to attach to his report and examina- 

 ation of the Hopetown and diamond-yielding district ! 



Mr. A. Wyley, the colonial geologist, gave ten years ago, and before 

 diamonds loere thought of as existing there, a careful geological de- 

 scription of the Hopetown district, which Mr. Gregory may consult 

 with advantage. He will find a copy of this report in the Geological 

 Society's Library, which I sent through Professor Eupert Jones. It 

 is entitled "Notes of a Journey in two directions across the colony 

 made in 1857-8," by A. Wyley, Esq., Geological Surveyor to the 

 colony, 1859. He describes the country as consisting of Sandstones, 

 Shales, and Schists, intersected by basaltic trap-dykes, etc. ; in fact 

 very similar to the great basaltic plateaus and horizontal Sandstone 

 formations in India, where the most celebrated diamond formations 

 occur, and to which I think it will be found our diamond-bearing 

 formations bear a strong resemblance. Mr. Gregory, in describing the 

 conglomerate in which the Hopetown diamonds are found, insists on 

 what he terms " an important distinction," as being not a silicious 

 conglomerate, as those from Brazil, but as being sometimes formed 

 into a solid conglomerate by the aid of lime. But why should our 

 diamond conglomerates be necessarily like those of Brazil ? Why 

 not rather like those of India, to which, as I have stated, our rock 

 formations, our vast horizontal sandstones, capped and permeated by 

 basalt, and in many cases our fossils also, bear so striking a resem- 

 blance. In Malcolmson's paper on " The Great Basaltic District of 

 India, and the Diamond Sandstones and Argillaceous Limestones," 

 published in the Geological Transactions, 2ud series, vol. v., lie says. 



