Fertility of some Coloiiial Soils. 25 



largely derived from the quartzites of the Zuurberg range, which 

 is entirely built up of rocks of the Witteberg series ; while almost 

 throughout the whole of the Humansdorp Division the soil is the 

 result solely of disintegration of the great ranges of Table Mountain 

 sandstone which extend along the south coast from George, and 

 eventually die out in the Zitzikama range. These sandstones and 

 quartzites contain practically nothing capable of affording nutriment 

 to plants, and are almost devoid of the very mineral salts essential 

 for the production of bone material. It would be of more than 

 interest to have the areas that are covered by these poor soils 

 mapped out as exactly as possible, so as to show their extent, and 

 yet these all-important investigations have been absolutely dormant 

 these seven years past. 



The average results of the above Witteberg soils may as well 

 be added for comparison with those already given: they are as 

 follows : — 



Lime 'OSl 



Potash -058 



Phosphoric oxide -065 



These soils, as before remarked, may be expected to resemble 

 those from the similar sandstones of the Table Mountain series. 

 There is, however, more clayey material in the Witteberg rocks, and 

 hence — if the subject were more closely investigated — we should 

 probably discover that the soils derived from them do not exhibit 

 quite the absolute poverty of the Table Mountain sandstone soils : 

 it is true that the above four analyses representing the Witteberg 

 series are along the line of this view, but they are altogether too few 

 in number to add any confirmation thereto. 



The soils derived from the Dwyka series, which overlie the Witte- 

 berg beds, lead us from the Cape into the Karroo System, w^here we 

 meet with an all-round richer type of soil than the average of the 

 older system. Of the soils which represent the Dwyka beds of 

 shales and conglomerates we have unfortunately examined only two 

 that can be taken as in any way typical, and both of these were 

 collected within the Worcester Division : their analyses resulted 

 as follows : — 



XI. DWYKA SOILS. 



Serial 

 No. 



Division 



Farm. 



Fine 

 Earth. 



Water. 



Organic 



Matter. 



Lime. 



Potash. 



Phos- 

 phoric 

 Oxide. 



145 



Worcester 



" 



De Hoek 



841 

 86-6 



3-80 

 108 



6-85 

 2-54 



1-640 

 •386 



•157 

 •119 



065 



146 



Aan de Doom Rivier 



052 



