Mr. Bain on the Geology of Southern Africa. 181 



The Lower Silurian *. 



This is also widely developed; it consists of unfossiliferous sandstone and 

 conglomerate, and forms the summits of Table Mountain and Lion's Head, as well 

 as that of all the extensive and lofty ranges of the western and southern parts of 

 the colony. 



A very good description of it has been given, as far as it refers to the neighbour- 

 hood of Cape Town, in Clarke Abel's Travels, p. 295, to which I may with con- 

 fidence refer. But I must at the same time observe that the imbedded pebbles 

 very much decrease in numbers in an easterly direction, but increase as the range 

 trends northerly ; for at Pikeneers Kloof and Rinoster Hoek the whole mountain 

 seems to be one mass of conglomerate, many of the imbedded stones being larger 

 than a man's fist. 



Those imbedded stones and pebbles being principally composed of clayslate and 

 quartz, it becomes a matter of interesting speculation as to the district whence 

 they were derived. No antecedent quartzose rock (excepting the quartz-veins in 

 the clayslate) at present exists in South Africa ; hence we must conclude that the 

 parent of those numerous pebbles and conglomerates now lies buried in the depths 

 of the Atlantic or Indian Oceans. 



When this sandstone is seen to rest on the granite, as it does at Lion's Head 

 (see Section 4) and at Du Zoits Kloof, it is evident that the granite had cooled 

 down and was perfectly quiescent at the time of the deposition of the former ; 

 showing a very marked difference between the junction of the gneiss with the 

 granite, and of the latter with the sandstone, — both of which are shown in this 

 section. 



The thickness of this formation it is difficult to ascertain ; but, as far as I have 

 been enabled to estimate it, it cannot be less than from 10,000 to 12,000 feet; so 

 that, if Table Mountain was ever covered with a like thickness of deposit, which 

 I have no doubt it was, and had retained it until the present day, then it would 

 eclipse the Peak of Teneriffe, or even rival Mont Blanc in altitude. 



To the advocates for the sudden upheaval of mountains, I think the removal of 

 such a mass from the top of Table Mountain presents a considerable difficulty : 

 but, compared to the immense denudation that has taken place in this formation 

 on the Cape Flats alone, to say nothing of the extensive valleys of elevation 

 leading from Tulbagh by Worcester, Swellendam, and George, and from Bain's 

 Kloof to Picket Berg and Donkin's Bay, it is a mere nothing. A glance at Section 



* The author's nomenclature is here retained : the probable geological age assigned by Mr. D. Sharpe 

 and Mr. Salter to the fossiliferous rocks immediately overlying this sandstone will be seen in subsequent 

 pages to be " Devonian." — En. 



