68 Transactions of the South African Philosophical Society. 



example, the various tributaries of the Kraai River, the Telle 

 Eiver, &c. By the excavation of the rocks the rivers formed valleys 

 whose floors became gradually flatter and flatter as the grade of the 

 river-beds became smaller and smaller. As the vertical erosion 

 became less and less the rivers eroded laterally, and finally wide 

 plains were produced across which the rivers flowed sluggishly in 

 numerous serpentine loops and bends. 



These plains of river erosion were formed in a period during which 

 the level of the earth's crust was but slightly affected by earth-move- 

 ments, so that the rivers were able to cut down to their base-level. 

 If a period of elevation followed, the downward erosive action of 

 the rivers was resumed, and the loops and bends of the streams were 

 perpetuated in deep gorges. When the elevation ceased a second 

 and lower plain of river erosion, or peneplain as it is termed, would 

 be formed. 



These peneplains are very well developed in this area, more 

 especially in Barkly East. The highest plateau is found at an 

 altitude of a little over 8,000 feet above sea-level, around the village 

 of Ehodes, and extends to the present escarpment of the Drakens- 

 berg, overlooking Maclear. On the north, some peaks along the 

 Witteberg Range indicate the higher ground which bounded the 

 peneplain in that direction. It is evident that the plateau once 

 must have extended further to the south and south-east until it 

 reached higher ground forming the watershed, and separating the 

 drainage area of the Kraai Eiver from that of the Tsitsa and Tina 

 Rivers. 



How far away that may have been situated from the present 

 watershed we have no idea ; it was probably many miles, but all the 

 beds have since been removed by denudation. An elevation of 

 a couple of thousand feet followed, and the rivers cut down and 

 formed a peneplain at an altitude of about 6,000 feet above sea-level. 

 This was a most extensive plateau ; much of it still remains in the 

 Kraai River valley, and there is no doubt that it extended away to 

 Dordrecht and Jamestown. A continuation of this peneplain is 

 found along the Orange River, in Basutoland. 



On the south-east side of the Drakensberg the high ground around 

 Cala, Engcobo, and Bazeia is probably a remnant of a peneplain at 

 about the same altitude, but the country has been greatly denuded. 



A second period of upheaval followed, and a peneplain at an 

 altitude of between 4,500 and 5,000 feet formed, which covers 

 an extensive area in Albert, Aliwal North, Herschel, and the 

 Orange River Colony. Beds of river gravels are common at many 

 points over this vast area. Even then the crust of the earth was 



