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-
