78
WALLACE H. FULLER
includes Angola, the Republic of South Africa, Southwest Africa, and
Botswana. Desert land in Angola is small. The general soil patterns follow
the rainfall distribution which increases from the Southwest to the Northeast (d'Hoore, 1964). The southwest African Desert may be roughly divided into three parts according to soil-climate interrelationships: (1)
desert soils—south and west, (2) semidesert soils—south and middle, and
(3) dry forest soils—north. In the Namib Desert three types of soil materials are delineated (Koch, 1962; Giess, 1962), (a) sands in a narrow
strip along the coast, (b) sand dunes (Ergs) south of the Kuiseb River,
and (c) stony and gravelly plains (Regs) north of the Kuiseb River on
the Namib Flats (Dregne, 1967). Dregne points out that inland from the
Namib Desert along the coast some weakly developed semiarid brown
soil occur as small inclusions in the barren mountain ridge. The Kalahari
Desert is east of these mountains and extends for great distances as a flat
plain. Lime accumulations are common and exposed except where they
are covered with thin layers of sand. The desert is divided into two general
groups, brown to reddish brown desert soil over sand and ferruginous
tropical soil also on sandy material where rainfall is higher.
Surface structures peculiar to the Kalahari Desert include indurated lime
surfaces (calcrete), gypsum beds (gypcrete), siliceous layers (silcrete)
from relic soils, ferrugenous desert pavements, loose sand and dune
and clay pans (playas). Grasses at one time dominated the Kalahari
Desert. Overgrazing has left much of the land barren and eroded (Debenham, 1952).
The Namib Desert has no vegetation except along its major river, the
Kuiseb, flood plain.
Desert pebble and stone pavement are prominent in the South African
Cape Province (van der Merwe, 1954). Lime-crusted and saline soils also
occur. Most of the soils of the Kalahari-Namib Desert area are quite deep
but the presence of indurated lime and silicate surfaces, stony pavements,
shifting sand dunes, and saline spots breaks the continuity of the better
soils.
B. SAHARA
The Sahara Desert is one of the most barren and harshest of world
deserts. Soil development in the large center area is weak where it
exists, and consists mostly of structureless shifting dune sand. Other desert
detritus and rock debris are little altered in the absence of rainfall and
vegetation. This extremely arid part is represented by a strip approximately
1250 km wide and 4000 km long. Fortunately, not all of the Sahara is
this dry and so little known. Desert soils have been described for the irrigated peripheral areas including oases and the Nile Valley in Egypt and
Sudan.
WALLACE H. FULLER
includes Angola, the Republic of South Africa, Southwest Africa, and
Botswana. Desert land in Angola is small. The general soil patterns follow
the rainfall distribution which increases from the Southwest to the Northeast (d'Hoore, 1964). The southwest African Desert may be roughly divided into three parts according to soil-climate interrelationships: (1)
desert soils—south and west, (2) semidesert soils—south and middle, and
(3) dry forest soils—north. In the Namib Desert three types of soil materials are delineated (Koch, 1962; Giess, 1962), (a) sands in a narrow
strip along the coast, (b) sand dunes (Ergs) south of the Kuiseb River,
and (c) stony and gravelly plains (Regs) north of the Kuiseb River on
the Namib Flats (Dregne, 1967). Dregne points out that inland from the
Namib Desert along the coast some weakly developed semiarid brown
soil occur as small inclusions in the barren mountain ridge. The Kalahari
Desert is east of these mountains and extends for great distances as a flat
plain. Lime accumulations are common and exposed except where they
are covered with thin layers of sand. The desert is divided into two general
groups, brown to reddish brown desert soil over sand and ferruginous
tropical soil also on sandy material where rainfall is higher.
Surface structures peculiar to the Kalahari Desert include indurated lime
surfaces (calcrete), gypsum beds (gypcrete), siliceous layers (silcrete)
from relic soils, ferrugenous desert pavements, loose sand and dune
and clay pans (playas). Grasses at one time dominated the Kalahari
Desert. Overgrazing has left much of the land barren and eroded (Debenham, 1952).
The Namib Desert has no vegetation except along its major river, the
Kuiseb, flood plain.
Desert pebble and stone pavement are prominent in the South African
Cape Province (van der Merwe, 1954). Lime-crusted and saline soils also
occur. Most of the soils of the Kalahari-Namib Desert area are quite deep
but the presence of indurated lime and silicate surfaces, stony pavements,
shifting sand dunes, and saline spots breaks the continuity of the better
soils.
B. SAHARA
The Sahara Desert is one of the most barren and harshest of world
deserts. Soil development in the large center area is weak where it
exists, and consists mostly of structureless shifting dune sand. Other desert
detritus and rock debris are little altered in the absence of rainfall and
vegetation. This extremely arid part is represented by a strip approximately
1250 km wide and 4000 km long. Fortunately, not all of the Sahara is
this dry and so little known. Desert soils have been described for the irrigated peripheral areas including oases and the Nile Valley in Egypt and
Sudan.