142 Transactions of the South African Philosophical Society. 
i) 
) o =| 2 
- Name of Farm and No. 3 a3 = 8 5 a ae 
of Sample. 3 ie iS) g 3 $s aie 
= OF 5 7, esl a 
Py 
Field-Cornetcy : Zoetendals 
Valler’ | 
112° Moere Kraal -......-.00.. 95 oa | 2014 15 228; i) LoeaeO 20m 
1B oRilands Drift’ 222... 1°18 B208 | O08) to iy dS a LOPS OrS 
DivistoN—ROBERTSON | | 
Field-Cornetcy: Robertson | 
tae Kieur aloo... .ceasscnee se aL 2 OMe) ONE EN Nie a Ola 
On comparing the map showing the various localities whence the 
foregoing samples were collected with the diagram (Plate XVII.), 
which illustrates the chemical composition of each sample a few broad 
features strike one. The first is this, that the amount of available 
lime averages ‘5 per cent. in the soils about Durban, thins out to 
about ‘1 per cent., and even less in the northern part of the Koeberg 
district, and remains fairly uniform as we go north to near Hope- 
field, the average percentage of lime in the 35-soils.collected on the 
clay slate formation in the Field-Cornetcies, Koeberg No. 2, 
Blaauwberg, Mosselbank River, Middle Zwartland, Groene Kloof 
East, Honing Berg, and Zwartland being only -078 per cent.; in 
other words, the average soil in the area just monuoneds is decidedly 
poor in lime. 
The following will show this more clearly : The four soils collected 
within the Field-Cornetcy of Tygerberg and Kuils River, Nos. 40 to 
43, yielded an average percentage of ‘47 of available lime. The next 
strip of country, lying to the north of this, and mainly within the 
Durban Field-Cornetcy, represented by the seven samples 44 to 49 and 
54 gave an average of *23 per cent. Next.come Nos. 00 to 53, north 
of Durban, and constituting the southern portion of the Koeberg 
district ; these give an average of ‘13 per cent. of lime. The middle 
part of the same district, comprising Nos. 55 to 62—8 samples in 
all—yields an average of -10 per cent. In the northern portion of 
Koeberg and the southern part of Zwartland we have the samples 
63, 64, and 65, giving an average percentage of 059. As we go 
further north we pass over samples 71 and 72, which are humus 
soils and probably also affected by the granite boss to eastward as 
well as the extent of granite lying to the west. Nos, 69, 70, and 73 
represent the next area, and the average in this case is ‘049 per cent. 
After this it becomes difficult to trace the gradation owing to the 
