148 GEOLOGY. 



here and there in the gorges at the foot of the Randt, and are 

 metamorphic rocks, greatly denuded, on which the extensive siliceo- 

 calcareous beds of the Great Campbell Plateau lie unconformably. 

 These last and the breccias of their slopes are covered with enormous 

 travertine-deposits. Beyond the Plateau, at Griquatown, a long 

 parallel range of jaspideous rocks comes out from beneath the Campbell 

 Plateau, and presents a group of yellow, brown, chocolate- coloured, 

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

 blue and yellow crocidolite. The southern part 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 lie 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 mica, also parallel to the former 

 ranges. The maximum thickness of the successive beds is 24,000 

 feet; allowing for possible reduplications, the minimum is 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 are treated of. T. R. J. 

 Ye LAIN, Ch. Constitution geologique des iles voisines du littoral 

 de I'Afrique, du Maroc a la Tunisie. [Geology of the Islands off 

 the Coast of Marocco and Tunis.] Compt. Rend. t. Ixxviii. 

 pp. 70-74. 

 Lafarine Islands : three small islands, mainly formed of granitoid 

 trachyte. In part the islands are covered by reddish travertines, with 

 land-sheUs. These tuffs are well developed on the mainland, thus 

 affording a means of determining approximately the date of the 

 severance of the islands from the continent. Rachsgoun Isla.nd is 

 composed of a grey compact basalt, with volcanic scorige and reddish 

 pozzolana, which has been worked for hydraulic cement. Quaternary 

 deposits, 100 feet thick, with land-shells of species now living in 

 Algeria, are found at the southern end. Hahibas Isles, very far from 

 land : formed of eruptive rocks, chiefly siliceous trachytic porphyries, 

 and peculiar green serpentine-rocks, besides some gypsiferous marls. 

 Plane Isle : a mere rock formed of Marmorean Limestones and 

 ferruginous Dolomites ; these rocks are metamorphosed Jurassic. 

 La Galite Isles, off the Tunisian coast: Trachytic rocks very ana- 

 logous to the Andesites of Ecuador &c. Sedimentary rocks are found, 

 but altered, and without fossils. Recent reddish calcareous tuffs, with 

 land-shells, overlie most of the rocks. . G. A. L. 

 YiRLET n'AoTJST, — . Observations sur Tancienne mer interieure du 

 Sahara tuniso-algerien. [The old inland sea of the Tuniso-Algerine 

 Sahara.] Compt. Rend. t. Ixxix. pp. 794, 795. 

 The writer brings one of M. Elie de Beaumont's lines of upheaval 

 to bear on the question of the modern separation between the ancient 

 bay of Triton and the Mediterranean. G. A. L. 



