16 



Transactions of the South African Philosophical Society. 



the analyses of the soils collected from this strip, beginning with the 

 sandstone-encircled tip and working downwards : — 



II. TONGUE OF MALMESBUEY SERIES EXTENDING FROM THE 

 VICINITY OF ROBERTSON TO THE WINTERHOEK MOUN- 

 TAIN NORTH OF TULBAGH. 



Serial 

 No. 



Division. 



Farm. 



Fine 

 Earth. 



Water. 



Organic 



Matter. 



Lime. 



Potash. 



Phos- 

 phoric 

 Oxide. 



15 

 16 

 17 

 18 

 19 

 20 

 21 



Tulbagh... 

 Worcester 



Misgund 



KnolleVallei 



Khiitjes Kraal 



Breede Rivier 



Wilge Bivier 



73-4 

 61-4 

 98-7 

 94-8 

 83-4 

 53-7 

 100 

 70-9 

 89-6 

 700 

 75-5 



•95 

 1-49 

 5-75 

 2-92 

 1-34 

 219 

 2-09 



•79 

 159 



•78 

 1-45 



351 



3^64 

 1009 

 11^78 

 3-77 

 7-55 

 6-62 

 3^47 

 404 

 2-98 

 3^64 





044 

 068 

 008 

 070 

 086 

 150 

 066 

 016 

 260 

 038 

 156 





032 

 038 

 030 

 095 

 027 

 147 

 037 

 091 

 195 

 158 

 068 



•023 

 •047 

 •023 

 •070 

 •034 

 •093 

 •069 



22 

 23 

 24 

 25 



Hartebeest Rivier 



Zeekoegat 



Tweefontein 



Nonna 



•051 

 •089 

 •078 

 •063 



In many places the soils resulting from the rocks of the Malmes- 

 bury series are diversified by the intrusion of granite. The conse- 

 quent diversity is more than becomes evident at first sight, for, 

 although poverty in plant food is practically inherent in the soils of 

 the Malmesbury series, it is otherwise with those derived from 

 granite. This is owing to the fact that while the Malmesbury rocks 

 are deficient in plant-food constituents, the intrusive granite is not, 

 and thus the resulting granitic soils impart to the clay-slate soils 

 not only plant-food constituents, proportionate to the relative quan- 

 tities in which the two classes of soil are mixed, but also actual 

 plant food, proportionate to the amount of decomposition that the 

 granite has undergone. Where the granite has not been sufficiently 

 decomposed the elements of fertility contained in its constituent 

 minerals are not available for the plant ; in other words, sufficiency 

 of plant-food constituents may then be present in the soil while there 

 is lack of plant food. The diversification of the clays derived from 

 the Malmesbury slates, consequent n^on the introduction of granite 

 as a soil-forming factor, is therefore dependent not only on the rela- 

 tive quantities wherein these two classes of rock contribute to the 

 formation of any particular soil, but also on the stage which the 

 mechanical disintegration and chemical decomposition of the granite 

 has reached. 



These facts naturally add to the difficulty of laying down anything 

 like a typical composition even for unmixed granitic soils. It may 

 be remembered that, in the course of my previous paper on this 

 subject, mention was made of several granite soils that had been 

 analysed by Professor Hahn. In one — an alluvial soil — the con- 



