Vol. 62.] IN THE SOUTH-WEST OF CAPE COLONY. 79 



know that, at many places where there are shallow lakes and lagoons, 

 there are hollows in the rock-shelf; but these are distributed so 

 irregularly that they can offer no support to the theory that running 

 water was the cause of the cutting of the Flats. 



Near Cape Point there is a raised beach about 100 feet above 

 sea-level ; and Mr. A. W. Rogers describes some very well-marked 

 shingle-deposits on the same level on the western coast, near the Van 

 Rhyn's-Dorp area. 1 At the base is a conglomerate strongly impreg- 

 nated with iron-oxide ; the pebbles are of all sizes up to a foot in 

 diameter, and consist of a considerable variety of rocks — sandstones, 

 quartzites, schistose quartzites, granites, quartz-porphyries, vein- 

 quartz, and slates. Above this layer come more or less ferru- 

 ginous sandstones, which are in places silicified. In Bamboes Bay, 

 3 miles south of Strandfontein, the ferruginous conglomerate passes 

 upwards into sandstones, and these again into calcareous beach- 

 deposits containing shells of species still living on the coast. The 

 country behind the coast, at a distance of 4 miles from it, lies 

 between 500 and 600 feet above sea-level. It would be very interest- 

 ing to follow the surf-cut levels northwards. At Port Elizabeth and 

 Uitenhage, the beach-deposits and shell-banks lie on a shelf about 

 200 feet above sea-level ; but this slopes gradually up to 600 feet, 

 and I am inclined to reckon the 100-foot level as a substage of the 

 Uplands plateau. 



We have, then, a plateau 700 feet above sea-level, and one at 

 about sea-level. I will now discuss one at considerable depths 

 below : this is the plateau the edge of which is known as the 

 Agulhas Bank. 



Soundings off the south-western corner of South Africa soon get 

 into depths of 40 to 50 fathoms ; and then, out to sea, there is 

 a gradual slope of the sea-bottom to 90 or 100 fathoms. The 

 marine charts seem to express a succession of ledges rather than 

 one continuous slope, one of the plateaux being at 45 to 60 fathoms, 

 another at 70 to 80 fathoms, and an outer one at 90 to 100. Close 

 in-shore, along the Zitzikamma, is a narrow shelf at 30 fathoms, 

 with a sharp drop off the edge to 50 fathoms. At one place on the 

 plateau there is a sounding of 134 fathoms which may be simply an 

 embayment, but also it may be a rock-channel, which once carried 

 the waters of the Breede River out to sea at this point, nearly 

 100 miles from its present mouth. The effect of a rise of the 

 continent of 600 feet would prolong the land some 150 miles 

 to the south, with the apex of the point shifted somewhat to 

 the east of where it now lies. We should then have two well- 

 marked plateaux: one at 600 feet, more or less, and one at 1300 feet, 

 more or less, above sea-level, besides the one at or near sea-level. 

 As it is, the remnants of one are found to exist at about' 1500 feet, 



1 ' Geological Survey of Piquetberg, Clanwilliam, & Van Elavil's Dorp ' Ann. 

 Rep. Geol. Comm. 1903 (Cape Town, 1904) pp. 161-62. 



