171 



is now being carried away into the sea by the Gouritz River, especially 

 at times of disastrous flood, although, as previously observed, some of it 

 is retained and deposited in the Mossel Bay and Riversdale Divisions as 

 the river passes through them o<n its seaward course.* 



Eleven analyses of such river deposits have been made by means of 

 the standard method, with the results below given: 



XVI. ALLUVIAL SILTS AND RIVER DEPOSITS. 



Division. 

 Gordonia. 



Albert. 



Prieska. 



Kimberley. 



Ladismith. 



S\vellendam. 



Knysna. 



Port St. John's 



River. 

 Orange. 



Vaal. 

 Buff els. 

 Tomvs. 



Farm. 

 Upington. 



Odendalstroom. 



Zeekoebaard. 



Warrenton. 



Buffelsvallei. 



Zeekoegatsdrift. 



Zevenfontein. 

 Keurbooms. Matjesfontein. 

 St. John's. Isinuka. 



Phosphoric 

 Lime. Potash, oxide. 



582 

 400 

 1-372 

 1-444 

 278 

 346 

 332 

 344 

 220 

 544 

 520 



093 

 065 

 042 

 473 

 108 

 094 

 166 

 187 

 146 

 105 

 171 



061 

 052 

 149 

 221 

 074 

 070 

 106 

 097 

 082 

 110 

 137 



They show considerable variety, both, in texture and in chemical com- 

 position. The proportions of lime, potash, and phosphoric oxide average 

 as follows : 



Lime 



Potash 



Phosphoric oxide 



584 

 153 

 106 



The following is a summary of the average results obtained from the 

 various types of soil reviewed. It may serve to bring out more clearly the 

 characteristic differences in respect of plant food. The low water-retaining 

 capacity of the soils of the Malmesbury and Table Mountain series will be 

 noted, as also the large amounts of moisture retained by the Upper Karroo 

 soils of the Burghersdorp-Stormsberg type: 



XVII. AVERAGES. 



Geological formation. 



No. of soils Phosphoric- 



analysed. Water. Lime. Potash. oxide. 



Pre-Cape rocks 



Cape System 



Karroo System 



Cretaceous System 

 Recent deposits : 



Malmesbury Series. 16 T02 '079 '124 '039 



Granite. 9 119 '049 '069 '048 



Campbell Rand Series. 7 3'99 4169 '048 '057 



Pniel Series. 9 2'90 '246 '068 '069 



Olive shales. 12 T48 '048 '055 '031 



Table Mountain Series. 46 1'08 '034 '031 '036 



Bokkeveld Series. 18 T27 '387 . '231 '118 



Common horizon of Table 11 '93 '042 141 '075 

 Mountain and Bokke- 

 veld Series. 



Witteberg Series. 4 3'49 '051 '058 '065 



Dwyka Series. 2 2"44 T013 138 '059 



Burghersdorp Beds and 24 2'29 '233 172 '078 



Stormberg Series. 



Uitenhage Series. 21 T44 '299 181 '087 



Sand Downs. 2 '078 '030 '027 



Transported Silts and River 11 2'86 '584 153 106 



deposits. 



*See pages 91, 96, 108, and 109. 



