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fogs more localized, it has less extensive dune fields,
and is dominated by nitrates rather than by gypsum
(Goudie, 2002, pp. 17-18).
regions present on the ground actually belies consider-
able variability and complexity. This has most obviously
been revealed not from the ground but from the air. To
this end, works such as
A study of global sand seas
(McKee, 1979), which utilised early Landsat satellite im-
agery to map the complexity and diversity of the dune
systems within individual sand seas, have done much to
lay down a basis for subsequent explanations of diversity,
based on analysis of meteorological station data and field
measurement.
McKee (1979) was not, however, the first time that
the generation of a bigger picture revealed within-desert
complexity. Alexander Du Toit used aerial survey as the
basis for his systematic
Kalahari Reconnaisance
(Du Toit,
1926) from which a better understanding of the topogra-
phy and hydrological connections of the region emerged,
allowing a scheme for dramatic river diversion and ir-
rigation in the region (Schwarz, 1920) to be quashed.
From a purely geomorphological perspective, the use of
aerial survey, via air photograph analysis, has played a
significant role in underpinning analysis of the complex-
ity of 'flat' drylands, which is no better illustrated than
by Grove (1958) for the Sahel and Grove (1969) for the
Kalahari.
Away from its uplifted margins, the Kalahari displays
no more than c.100 m relative relief over lateral distances
of up to 1000 km, save for isolated inselbergs. Largely
a sand-filled interior cratonic basin with a mean eleva-
tion of 1000 m a.s.l. (Thomas and Shaw, 1991), Grove's
(1969) analysis paved the way for systematic investiga-
tion of its actual considerable geomorphological diversity
(Figure 4.1) that is not obviously apparent on the ground.
Though much of the Kalahari is covered by sands that
have been shaped by the wind into dunefields (now pri-
marily vegetated) that show regional variations in orienta-
tions and dune type, the widespread occurrence of alluvial
and lacustrine deposits was also highlighted, along with
the distribution of largely dysfunctional drainage systems
and the local role of tectonic movements in disrupting
both drainage lines and locally displacing dune patterns.
Grove's work provided the basis of systematic geomor-
phological analyses of component parts of the Kalahari
landscape (e.g. dunes: Lancaster, 1981; Thomas, 1984;
pans: Lancaster, 1978; lake basins with associated
palaeoshorelines: Cooke, 1979; Shaw, 1984; valleys:
Nash, Thomas and Shaw, 1994). Beyond a landform-
based analysis, complexity has also been revealed with
the sands that themselves characterise the Kalahari, in
terms of their source regions and provenance as de-
fined by heavy mineral (e.g. Baillieul, 1975) and wider
statistical (Thomas, 1987) analysis. Within the deposi-
These differences are principally due to the contrasting
tectonic settings of these two deserts.
The previous discussion has provided a framework that
allows explanations to be sought for the diversity that
occurs between different desert and dryland areas. The
following sections illustrate the nature of drylands that
display considerable, and those that at first glance may
display little, internal diversity. The purpose is not to pro-
vide an account of the entire world's drylands: this is best
gained by reference to the detailed studies that prevail (e.g.
Thomas and Shaw, 1991, on the Kalahari and Lancaster,
1989, on the Namib) or summary texts such as Goudie
(2002).
4.2
Geomonotony: how unvarying are the
'flat' drylands of the world?
Many of the apparently flat dryland landscapes are domi-
nated by depositional (often aeolian) landscapes, but cer-
tainly not all, as 'flat' erosional landscapes in the form of
pediments and stony plains are also important dryland el-
ements. It is stable cratonic settings (Chapter 2) that most
obviously create the framework for 'flat' (depositional
or erosional) landscapes to develop. Such landscapes can
initially appear unvarying but, as the example below indi-
cates, marked geomorphological complexity emerges on
deeper analysis.
Livingstone (1857) described the semi-arid to arid
Kalahari Desert of central southern Africa as 'remark-
ably flat' (p. 47), while in 1912 its southern region
was described as 'dreary and depressing' because of its
monotonous and repetitive landscape of vegetated 'sand
hills' (Hodson, 1912). Similarly 'unimpressed' interpre-
tations of flat (or repetitive) dryland landscapes by early
European travellers can be found for parts of western
Australia, the North American mid-west and so on. While
this observation seemingly contradicts the previously ob-
served tendency for early landform accounts to focus on
the spectacular and unusual (see Chapter 1), it might also
provide a contributory explanation as to why the unusual
was often greeted with such enthusiasm.
The 'geomonotony'
1
of the apparently flat and end-
less swathes of terrain that some desert and dryland
1
With acknowledgement to Dr Frank Eckardt, remote sensor and geo-
morphologist, who has used this term to describe the experience many
