. The Quarterly journal of the Geological Society of London. c d. apparently Postpliocene, occurs at a higher level than the other, asoutliers along the present valley (its present position) indicate thatthe Vaal has deepened its course since the old drift was deposited. The famous Pniel Kopje was of this age, the depth of sinking,about 30 feet, consisting of a few feet of fine gravel, composedof agates, chalcedony, amygdaloid, dolerite, &c, with some gar-nets, ilmenite, topaz, quartz, and diamonds. Below this, in places,was a hard layer of conglomerate, the pebbles cemented with rema
. The Quarterly journal of the Geological Society of London. c d. apparently Postpliocene, occurs at a higher level than the other, asoutliers along the present valley (its present position) indicate thatthe Vaal has deepened its course since the old drift was deposited. The famous Pniel Kopje was of this age, the depth of sinking,about 30 feet, consisting of a few feet of fine gravel, composedof agates, chalcedony, amygdaloid, dolerite, &c, with some gar-nets, ilmenite, topaz, quartz, and diamonds. Below this, in places,was a hard layer of conglomerate, the pebbles cemented with remainder of the drift was composed of large boulders of igneousrock, exceedingly tough and hard, with fine drift containing diamondsfilling the interstices. The. bottom is soft igneous rock, probablydolerite. At Gong Gong a calcareous conglomerate occurs high abovethe recent drift, and appears to belong to the same age as the Pnieldrift. Wherever worked, along the course of the Vaal, diamonds Q. J. G. S. No. 117. f 58 E. J. DUNN ON THE MODE OP OCCURRENCE. Port Nolloth. Ooearbis Hill. Hill. Ookiep No. 6 Fontein. Pella Mount. w NG-aun. p o cd c - c? i-1 £? O *» -^g o S| ©«s th> hf. CD Pv CD ,©^3 NGannaia. o • 1—1 h-** TGaams. a 0E DIAMONDS IX SOUTH AFRICA. 59 were found in this drift. Some localities have yielded immensequantities, as Pniel, Klipdrift, &c. The newer one, or recent drift, occupies the present river-bed. It differs in composition from the older drift, in containing alarger percentage of sandstone pebbles and pebbles of soft general colour is greyish, while the older drift is of a reddishcolour. The newer drift contains the same well-rounded polishedpebbles of agate &c. as the older one. Diamond-workings have been successfully prosecuted for a conside-rable distance along the Vaal river. In the newer drift CawoodsHope was an unusually rich digging; while Waldecks Plant yieldedthe largest diamo
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