532 Geological Society .—The Rev. W. B. Clarke 



that it ranges between north and south. The cleavage, where it 

 can be detected, is nearly perpendicular to the horizon. Overlying 

 these schists and composing the upper part of the hill, is a yellowish, 

 argillaceous and sandy laminated rock, which presents the same 

 jointed structure and cleavage as the schist ; and owing to the in- 

 tersection of the joints, the beds divide into wedge-shaped masses, 

 or regular prisms with pyramidal terminations. Mr. Clarke is of 

 opinion that the subjacent schistose rocks have been intruded into 

 or amongst these upper beds, and he states that the grooved and 

 fluted surfaces betray the intensity of the forces with which the 

 slaty masses were ground against each other. He mentions a quarry 

 below the Lion's Rump at the back of Cape Town, as an example 

 of the disturbed position of the schist and overlying sandy rock. He 

 suggests that the schists may belong to the Cambrian, and the super- 

 jacent beds to the lower portion of the Silurian system. 



The schistose rocks occur also in Robben's Island ; and on the other 

 side of the Lion's Rump they form a reef of hard rock along the 

 shore, occurring at intervals at the bottom of Table Bay, and re-ap- 

 pearing in the rounded low range upon the opposite coast. Grooves 

 and scratches, as well as ripple-marks, are very prominent on many 

 of the slabs. 



2. District from Green Point to Camp's Bay. — The rocks which 

 form the general base of the Lion's Hill are stated to be best exa- 

 mined along the fiat shore which skirts it, and where the successive 

 formations crop out. The slate rocks gradually attain a nearly ver- 

 tical dip as they recede from the Lion's Rump ; and between their out- 

 crop in the sea, where they form the first line of barrier rocks, and 

 Green Point, they first change into mica-slate, which soon becomes 

 charged with hornblende, then presents a mottled aspect, and gneiss is 

 ultimately exposed in contact with granite. At the immediate junc- 

 tion of the gneiss with the granite the former is stated to be in some 

 places superficially black and vitreous, extremely hard, as vesicular 

 as lava, and to be most curiously contorted. Masses of true Lydian 

 stone and other metamorphic rocks are stated to be intercalated be- 

 tween the ridges of slate. The true beds in the vicinity of the 

 gneiss range from S.E. to N.W., but where that rock first appears, 

 the strata, as well as the sandstone, dip under the Lion's Rump at 

 an angle of 82° towards the N.E. One line of joints, called by the 

 author cleavage-joints, is stated to be inclined 18° to the W.S.W. ; 

 and some of the intercalated beds are said to have similar joints 

 dipping 23° to the N.W. Directly under the Lion's Head, where 

 the gneiss is in contact with the granite, the beds alter in their 

 direction about 5° to the west, the cleavage joints changing also to 

 a range of 30° to the west ; and the strata on the shore are in 

 utter confusion. At this point commences a series of highly curious 

 quartz veins, which intersect the gneiss, passing in some places 

 through the joints, as if of posterior origin to the change which pro- 

 duced that structure in the rock, and they throw off from each side 

 numerous branch veins, often at right angles to the main vein. The 

 gneiss is described as overlaid by granite, and the quartz veins to be 



