Chapter 17
Aeolian processes and erosive landforms
1. Introduction
Aeolian processes are those derived from wind activity, and they comprise erosion,
transport, and sedimentation. Small-sized particles are mobilized and, finally, deposited in
different environments, sometimes at a great distance from their source area. Desert winds
are able to build large dune fields, such as those of the Rub al Khali desert (Figure 17.1),
in the Arabian peninsula, that covers about 560,000 km 2 (Allison, 1997). Also, as a
consequence of aeolian processes, more than 300 m of loess were deposited in China
(Derbyshire, 1983a). Aeolian deposits are studied by different scientific disciplines such as
physics, geology, biology, and agronomy (Pye and Tsoar, 1990). This multidisciplinary
scientific research has provided significant advances in the knowledge of aeolian activity
and its effects. Recent research on aeolian geomorphology deals mainly with
quantification of processes, analyses of forms and internal structures of the aeolian
deposits, and also with the information that those supply in order to understand the
climates of the past.
From an historical perspective, during the 19th century, wind was considered as a
transporting agent of limited importance, in comparison with water. At the end of that
century, and at the beginning of the 20th century, the scientific trend reversed, and some
researchers (especially German ones such as Passarge and Walther) pointed out that
aeolian erosion was predominant in deserts, and inselbergs with their surrounding
plains were a consequence of wind activity (Goudie and Wilkinson, 1977). Research
activities focused on exploration of new territories and the description of landforms, and
were not particularly concerned with the connections between forms and processes.
Bagnold's (1941) work was a milestone in this subject because he quantified wind
characteristics and transport processes. Since then conventional aerial photographs have
become an important tool but the decisive boost started with research using satellite
images, clearly showing the geomorphic work of the wind (McKee, 1979a,b). With
these techniques it is possible to analyse yardang systems, that can extend up to
100,000 km 2 (Lybian desert, Tibesti massif, desert of Lut in Eastern Iran, and others).
Recent studies on orbital images from Mars and Venus show clearly the importance
of wind processes on these planets (Greeley and Iversen, 1985). The discovery of oil
and hydrocarbons in Mesozoic aeolian sandstones from Europe and USA was also a
stimulus to work on these subjects. Knowledge of the aeolian domain has increased with
the large number of absolute dates, carried out since 1980, using C-14 and luminescence
techniques.
Aeolian processes and erosive landforms
1. Introduction
Aeolian processes are those derived from wind activity, and they comprise erosion,
transport, and sedimentation. Small-sized particles are mobilized and, finally, deposited in
different environments, sometimes at a great distance from their source area. Desert winds
are able to build large dune fields, such as those of the Rub al Khali desert (Figure 17.1),
in the Arabian peninsula, that covers about 560,000 km 2 (Allison, 1997). Also, as a
consequence of aeolian processes, more than 300 m of loess were deposited in China
(Derbyshire, 1983a). Aeolian deposits are studied by different scientific disciplines such as
physics, geology, biology, and agronomy (Pye and Tsoar, 1990). This multidisciplinary
scientific research has provided significant advances in the knowledge of aeolian activity
and its effects. Recent research on aeolian geomorphology deals mainly with
quantification of processes, analyses of forms and internal structures of the aeolian
deposits, and also with the information that those supply in order to understand the
climates of the past.
From an historical perspective, during the 19th century, wind was considered as a
transporting agent of limited importance, in comparison with water. At the end of that
century, and at the beginning of the 20th century, the scientific trend reversed, and some
researchers (especially German ones such as Passarge and Walther) pointed out that
aeolian erosion was predominant in deserts, and inselbergs with their surrounding
plains were a consequence of wind activity (Goudie and Wilkinson, 1977). Research
activities focused on exploration of new territories and the description of landforms, and
were not particularly concerned with the connections between forms and processes.
Bagnold's (1941) work was a milestone in this subject because he quantified wind
characteristics and transport processes. Since then conventional aerial photographs have
become an important tool but the decisive boost started with research using satellite
images, clearly showing the geomorphic work of the wind (McKee, 1979a,b). With
these techniques it is possible to analyse yardang systems, that can extend up to
100,000 km 2 (Lybian desert, Tibesti massif, desert of Lut in Eastern Iran, and others).
Recent studies on orbital images from Mars and Venus show clearly the importance
of wind processes on these planets (Greeley and Iversen, 1985). The discovery of oil
and hydrocarbons in Mesozoic aeolian sandstones from Europe and USA was also a
stimulus to work on these subjects. Knowledge of the aeolian domain has increased with
the large number of absolute dates, carried out since 1980, using C-14 and luminescence
techniques.