347 



More important rivers traversing this region are the Swakop, 

 the Khuiseb, and the Khan, the latter a tributary of the Swakop 

 which it joins at Haikamchab. These carry water as far as the 

 sea, on the average, about once in seven years. "Within a few 

 miles of the coast the Khuiseb bed is flush with the surface, 

 while that of the Swakop is only a few feet below it. Higher up 

 both the Swakop and also the Khan (the Khuiseb I have not 

 followed for more than 5 or 6 miles inland) have eroded canons 

 so deep that their beds, bounded by unscalable cliffs, now lie 

 from 500 to 800 feet below the level of the Namib. For a mile— 

 in places much more than a mile — on each side of the main bed, 

 the orographical features of the country are extraordinarily com- 

 plicated by the deep winding" channels cut out by tributary 

 streams. For some distance south of Usakos the Khan basin is a 

 deep channel only 15 to 20 miles across, at the bottom of which 

 lies the present bed of the river like an abrupt and narrow furrow 

 in the middle of a storm- water drain. These facts again must 

 indicate that the rainfall, not only of the Namib, but probably also 

 of the higher land to the north and east, was sufficient to effect a 

 degree of denudation which the existing conditions, even if acting 

 through an indefinite period, could not possibly bring about. 



Flora (Plateau).— Among the most generally prevalent and 



characteristic of the plants of the Namib plateauf the first 

 place must probably be given to Zygophyllum Stapfii, Schinz, 

 a bush with thick,* fleshy, suborbicular, vertically-placed leaves, 

 one of the surprisingly few succulents met with. A Commiphora 

 ( ? C. saxicola, Engl.), a low shrub with very stout, spreading 

 branches, is abundant in the eastern part of Namib, whence 

 it extends beyond the desert boundaries into the transition 

 region ; both it and a Sarcocaulon ( ? S.Marlothii, Engl.), Fig. 3— 

 the small bush to the left in the background— of somewhat similar 

 habit and with rose-coloured petals, are commonly associated 

 with Welwitschia to the south of Welwitsch. Welwitschia, 

 Figs. 3, 4, and 5, was found fairly constantly both on the plateau 

 and also in the upper portions of the lateral valleys leading down 

 to the Swakop and Khan rivers, from a point about 6 miles 

 south-west of Haikamchab, north-eastwards to the railway sta ion 

 at Welwitsch (see map). East of the latter place I believe that it does 

 not occur. The first plant passed on the way to Haikamchab v> as 

 found just before sunrise. I have no doubt that its western linn 

 was crossed during the preceding night. Mr. Gale, ot "amsn 

 Bay, believes that it occurs as fax- south as the Tubas river channel. 

 There is a tradition among the natives that it has been found 

 within the memory of the present generation in the ™™ l y °J 

 Roodebank on the Khuiseb river. As far as I can learn it d oes not 

 occur there now. From all the information aval ab e »t ja uia 

 appear that in this locality the occurrence of ^ehutsdim is 

 imited to an area measuring not more than 2. miles from north 

 to south and 15 miles from west to east. Both Mr ^ ^ 

 Herr Bohr, an officer of the German Forest Department, have 



/.'., the hard surface on which the sand-dunes more. 

 _ t An extensive collection of these and of the P 1 ^. ^™* ^ ' Qalpin. A 

 Swakop river-beds was made during the journey, principally by Mr. uaipi 



"fit will be published later. 



