STOW SOUTH-AFRICAN GEOLOGY. 



509 



thick, interspersed with calcareous stripes. From this stratum (No. 

 1) small burrows or pipes have been sunk through the strata Nos. 

 2 & 3, and form cavities in No. 4, as delineated in Section N". 

 Some of these curious excavations are several feet in depth ; and in 

 some instances the lower part is 18 inches wide, while the pipes 

 leading to them are only a few inches in width ; they appear to be 

 the work of some of the old inhabitants of that ancient sea. They 

 are now aU filled with the sandy marl of No. 1, with which are 

 mixed small nodules, and, in some of the pipes, fragments of shells, 

 evidently aU washed in from above, when the apertures leading to 

 them were open. 



These clays dip E. by S. at an angle of 20°, and have been denuded, 

 as shown in the Section. The sandy marl and the outcrop of the 

 clays are covered with surface-soil, the lower part of which is inter- 

 spersed with beds of well-worn quartzite pebbles, in some parts to a 

 thickness of from 1 to 3 feet. In some places there is a small deposit 

 of calcareous tufa between the underlying clays and the surface-soil. 



In another excavation, near the same spot, I obtained a rather 

 different section of these stratified clays exposed for about 39 feet, 

 as seen at c, in Section (fig. 4). The dip here varied from 10° 

 to 20°. Whether the clays of these two last-mentioned Sections (N 



Fig. 5. — Section of the beds marked d in Fig. 4 *. (Section P of 

 Author.) From an excavation made for a large tank. 



Soil and pebbles. 



Tufa, 12-18 inches. 



Eather friable sandstone, interspersed with carbonate of lime, 2 feet. 



Tufaceous limestone, 5-7 inches. 



Sandstone, interspersed with carbonate of lime, 13 inches. 



Tufaceous limestone, 1 foot. 



Sandstone, 3 feet. 



Sandy limestone, 6 inches. 

 Sandstone, 7 inches. 

 f Sandy limestone, 6 inches. 



Sandstone, 1 foot. 

 Eeddish sandstone. 

 Bottom of excavation. 



and 0) are continued across the Salt Vlei to the opposite outlier d in 

 Section (fig. 4), I am not able to say, as the sides of this hill are 



* Possibly this section includes some Posttertiary deposits. 



