408 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 30, 



communication. A subsequent portion of the journey up the Hart, 

 across to the Vaal, down the valley by the diamond-diggings of 

 Hebron and Klipdrift to the Panneveldt, will be treated of in 

 another paper. 



From the Modder, first south-westward and then westward, to the 

 junction of the Vaal and Orange, the olive shales of the Dicynodon- 

 or Karoo- series, traversed frequently by igneous rocks, form the 

 country, and are seen in some places to lie unconformably on older 

 rocks. The shales reach to the edge of the Campbell Randt. on the 

 other side of the Orange River, and have been, it seems, to a great 

 extent, formed of the debris of those old hills. The oldest rocks of 

 the locality are seen cropping out here and there in the gorges at the 

 foot of the Randt, and consist of metamorphic rocks, greatly denuded, 

 on which the massive and extensive siliceo-calcareous strata of the 

 Great Campbell Plateau lie unconformably. These latter and the 

 breccias of their slopes are coated thickly with enormous travertine 

 deposits. Beyond the Plateau, at Griquatown, a long parallel range 

 of jaspideous rocks comes out from beneath the Campbell Plateau, 

 presenting a wonderful group of yellow, brown, chocolate, and red 

 jaspers, with magnetic and other ironstone, and beautiful seams of 

 blue and yellow crocidolite. The southern portion of this range has 

 long been known as the " Asbestos Mountains " and the " Doorn- 

 berg." Igneous rock-masses occur around Ongeluk, west of the 

 Jasper range ; and then bright-red jasper rocks crop up near Matsap, 

 succeeded to the west by the parallel quartzite range of Matsap, 

 and again by other bedded jaspers, which seem to He in a synclinal 

 of the quartzite rocks, which come up again in the Langeberg. These 

 are succeeded by lower rocks, consisting largely of sandstone, grit, 

 and quartzite, with more or less pervading mica, as far as the journey 

 extended in the Schurwe Bergen, also parallel to the former ranges. 

 The maximum thickness of the successive strata is calculated by the 

 author at 24,000 feet; allowing for possible reduplications, the 

 minimum is regarded as not less than 9000 feet. The details of 

 stratification, successive upheavals, denudation, nature and origin of 

 the salt-pans, escarpments, river-valleys, and other features were 

 treated of by the author, who has supplied a very large collection of 

 specimens illustrative of the phenomena observed in the line of 

 march, and of his numerous sections, maps, and sketches. 



Discussion. 



Prof. Hull suggested making thin slices from the limestone with 

 a view to microscopic examination, and offered to carry out this 

 suggestion. 



, Prof. Hughes observed that, by burning a limestone and suddenly 

 plunging it in water, fossils previously invisible were sometimes 

 manifested. 



Prof. Rupert Jones pointed out some interesting lithological 

 characters in some of the micaceous, jaspideous, and other rocks 

 sent by Mr. Stow. 



