Geoscience Reference
In-Depth Information
Figure 5.3. Gemmule membrane broken open to show interior, extracted from sponge
pottery, Shabona, lower White Nile Valley, Sudan. (SEM Photo: Don Adamson).
during the past few centuries (Whetton et al.,
1990
; Whetton and Rutherfurd,
1994
;
Whetton et al.,
1996
). We discuss the reasons for this synchronism in
Chapter 23
.
Lustig (
1968
) has provided a very detailed and useful annotated bibliography of the
geomorphology and surface hydrology of desert environments. It is not our intention
here to duplicate his work but simply to highlight some themes and questions raised
during the early stages of research on deserts.
5.2 The Sahara and Afar deserts
There are three reasons why it is appropriate to start with the Sahara. First, it is the
largest desert in the world, with an area in excess of 8 million km
2
. Second, it has
