163 



The above table of shale soils has been taken out of its proper geo- 

 logical order because of the local association of these soils with those- of 

 the Campbell Hand. Strictly speaking, it should be considered along 

 with the soils of the Dwyka series, of which these shales seem to form 

 part: chemically, however, the above soils differ greatly from the Dwyka 

 soils examined; to these reference will be made at a later stage. 



Another geological formation which it will be convenient to allude to 

 here, but which belongs to a much earlier geological age, is that of the 

 Pniel Volcanic series, a group of rocks that make their appearance still 

 further east, i.e., on the opposite side of the shales to the Campbell Rand. 

 From this formation the soils enumerated in the following table were col- 

 lected : 



VII. PNIEL VOLCANIC SERIES. 



Division. 



Farm. 



Fine earth. Water. 



Phosphoric 

 Lirne. Potash. oxide. 



Barkly West. Brady's. 



,5 



Patrys Kraal. 



JJ 



., Zwartputs. 



Vryburg. 



H.V. 67. 

 H.V. 63. 

 Luxmore. 



92-2 

 84-4 

 83-4 

 93'4 

 98-3 

 96-8 

 96-6 

 97-6 

 85-2 



94 

 116 

 2-02 

 3-33 



79 

 2-02 

 6-82 

 6-03 

 2-95 



044 

 020 

 082 

 240 

 020 

 082 

 1-037 

 461 

 220 



050 

 112 

 056 

 123 

 037 

 056 

 054 

 027 

 101 



031 

 045 

 038 

 031 

 022 

 038 

 195 

 154 

 063 



The Pniel group underlies the limestones of the Campbell Rand 

 series, and, including as it does amygdaloids and diabase, it appears to be 

 capable of producing chemically rich soils, but only under the condition 

 already pointed out in conection with the granite soils, mere disinte- 

 gration does not suffice ; it needs to be accompanied by chemical decom- 

 position in order to render the resulting soil fertile. 



The following are average results of the analyses of the Pniel series 

 soils : 



Lime '245 



Potash -068 



Phosphoric oxide '069 



Of the rocks of the Cape system, the lowest are those of the Table 

 Mountain series. Table Mountain sandstones and quartzites constitute 

 the greater part of the lofty mountain ranges which extend for hundreds 

 of -miles along the south-western part of the Colony : they tower above 

 all other rocks for very many miles around, and it is, therefore, a safe 

 assumption to make that the virgin soils, collected from these high alti- 

 tudes, are quite uninfluenced by any other geological formations. Fur- 

 thermore, the rocks cf the Table Mountain series consist of little else 

 than silica, namely, sandstones and quartzites, with occasional shales. It 

 may accordingly be anticipated that the soils thence derived will not be 

 of very complex chemical composition, but will, on the contrary, lack the 

 essential elements of plant food. Such we actually find to be the case. 

 The following is a table of analyses of 46 soils collected either directly 

 from areas formed of this sandstone, or from valleys so completely domi- 

 nated by ranges of the Table Mountain series as to render it practically 

 certain that no other ro^ck? could have appreciably contributed to their 

 composition. 



