Geological Society. 53 1 



points out its extremely low geological position, resting upon a cal- 

 careous stratum, which has been proved by its organic remains to be 

 the equivalent of the Wenlock limestone ; and he states that it is 

 of higher antiquity than the oldest salt-bearing beds of Russia. Mr. 

 Murchison also alludes to the great value of Mr. Hall's communica- 

 tion in proving the wide application of the palaeozoic succession esta- 

 blished in Great Britain. 



April 21. — A paper " On the Geological Phsenomena in the Vici- 

 nity of Cape Town, Southern Africa," by the Rev. W. B. Clarke, 

 F.G.S., was read. 



Mr. Clarke commences by stating, that having derived no advan- 

 tage from the labours of previous geologists, his remarks must be 

 regarded as independent of any prior description. He arranges his 

 details under the heads of Physical aspect, Mineral structure, and 

 Geological changes. 



1 . Physical aspect. — The leading physical features are the mag- 

 nificent serrated mountains called Blue Berg or Hottentot's Hol- 

 land, which stretch northward for many miles into the interior ; 

 and the promontory which extends from Table Mountain to the 

 Cape of Good Hope. Each of these ranges consists of flat-topped 

 masses interspersed with pyramidal or pointed peaks, and separated 

 by deep ravines ; and Mr. Clarke states that their outline is evidently 

 owing to deep vertical fissures intersecting horizontal strata, proving 

 also that the Table Mountain is not a solitary example of the fea- 

 ture to which it owes its name. A level area extends from the base 

 of the Blue Berg to the shore ; and between the southern termina- 

 tion of that range and Table Mountain, is the low sandy district 

 called the Table Flats, forming an isthmus between Table Bay and 

 False Bay. A prominent but subordinate physical feature is the 

 Lion's Hill, situated below Table Mountain ; at the entrance of the 

 Bay is Robben's Island, and between the base of the Blue Berg and 

 the shore is a low range of hills of limited extent. 



False Bay is bounded on the west by the Cape Promontory, and 

 on the east by a continuation of the Blue Berg, presenting the same 

 physical structure and geological aspect as the Promontory. 



Mineral structure and position. — In detailing the composition of 

 the rocks and the associated phenomena, Mr. Clarke describes sepa- 

 rately, and in the following order, first, each of the principal physical 

 masses ; namely, the Lion's Rump, the district between Green Point 

 and Camp's Bay, that between Camp's Bay and Cobler's Hole, the 

 Kloof, and Table Mountain ; and secondly, the modern deposits, 

 springs and detritus. 



The Lion's Rump. — The lowest deposit at the Lion's Rump varies 

 in characters from a glossy soft slate to a hard and siliceous, as well 

 as a crystalline schist, and occasionally to a rock as close-grained as 

 bassanite. The partings of the masses are stated to be frequently 

 lined with a substance resembling soapstone and serpentine ; and 

 the intersection of the joints giving the strata a somewhat columnar 

 structure, the rock presents a basaltic aspect. The true line of bed- 

 ding is not easily to be distinguished, but the author is of opinion 



