RHOOESIA 
BECHUANALANO 
PROTECTORATE 
,MOQAMBIQUE 
MARIENTAL 
HvryburgI 
SOUTH WE: 
ORANGE 
(STATE 
'howick 
JASUTC 
[BEDFORD j 
Fig. 1. Map of South Africa showing location of mapping sites in relation to isohyets 
WORKING GROUP 9 
BRINK 
Einheiten sind: Geländeformen, Entwässerungssystem, Grauton. Oberflächen-Habitus und 
natürlicher Pflanzenwuchs - in dieser Reihenfolge. 
Auf der definitiven Karte wird das anstehende Gestein in Farbnuancen angegeben und die 
darüber liegenden Bodengattungen durch entsprechende Schraffierungen und Bodenprofil- 
Symbole erkenntlich gemacht. Allgemein wurde beobachtet,dass Luftbilder in grösserem 
Masstab benötigt werden für Untersuchungen von Gebieten mit reichlichem Niederschlag, 
während in trockenen Regionen das Material in Luftbildern kleineren Masstabes und in 
grösseren Einzelheiten umgrenzt werden kann. Die anfängliche Untersuchung hat auf die 
Notwendigkeit einer regionalen Einteilung des Landes auf Grund geologischer und klima 
tischer Verhältnisse hingewiesen. Weitere Arbeit wird die Kartierung repräsentativer Gebiete 
innerhalb jeder solcher Region zum Ziele haben. 
499 
The selection of soil samples for highway design in South Africa is based on 
a well established but somewhat empirical procedure. Samples are selected 
from each layer of the soil profile at ten points to the mile, and down to a depth 
of 24 inches below ground level in areas of fill, or to about 18 inches below 
grade line along level stretches and in areas of cut. Prospecting for suitable 
construction materials is based on entirely arbitrary procedures: the prospector 
seldom has more than his own experience and intuition to assist him. Detailed 
geological maps cover only limited areas of the country and, even where they 
are available, seldom include information about surface deposits such as 
natural gravels, ferricretes and calcretes, which may be the very materials for 
which the road engineer is prospecting. Likewise, the areas covered by detailed 
agricultural soil maps are as yet very few and far between, and contain little 
information concerning solid rock. 
Consequently it has been realised that the engineer needs a map which will 
indicate the distribution of all materials along a proposed route, from the sur-