Geoscience Reference
In-Depth Information
a wider audience (Wood,
2002
). The geographer Ellsworth Huntington (
1907
;
1945
)
invoked historic droughts following earlier pluvial climates as a primary cause of the
periodic migrations of the Mongol nomads into China and Russia. The geological
expedition led by Berkey and Morris (
1927
) into Mongolia also noted evidence of
previously wetter climates in this presently arid region.
The German geographer-explorer Baron Ferdinand von Richthofen referred to
these historic trade routes collectively as the
Seidenstrasse
,orthe
Silk Road
,aname
that immediately attracted popular romantic interest (Wood,
2002
). Chinese officials
kept detailed lists of goods traded and of the peoples involved from the time of the Han
dynasty onwards. They also recorded unusual weather phenomena, dust storms and
when certain flowering plants blossomed, all of which provide an unrivalled archive
of historic climatic fluctuations (Anon.,
1981
; Chu,
1973
; Godley,
2002
;and
Chapter
23
). Richthofen (
1877
-
1885
;
1882
) also drew scientific attention to the great loess
deposits of central China.
Nineteenth-century rivalry between the expanding Russian Empire and the British
in India led to clandestine forays by both sides to map the rivers, lakes and moun-
tains in the huge region between central Asia and the Himalayas, including Tibet
and Afghanistan (Hopkirk,
2010
). The once independent desert cities of Bokhara,
Tashkent and Samarkand later fell under Russian control, while the British maintained
an uneasy presence in northern Pakistan and Afghanistan. Further east, scholarly sci-
entific explorers such as Sven Hedin (in 1897 and again in 1900-1901) and Nikolai
Przhevalky (from 1870 to 1872) documented the natural history and geography of
Asia's largest desert, the Gobi, which covers some 1.3 million km
2
,aswellasthe
Alashan Plateau in what is now Inner Mongolia and the Taklamakan desert. The geo-
logical work by Berkey and Morris (
1927
) provided the first substantive account of
Mongolian geology and had a major influence on later accounts of arid zone geomor-
phology (e.g., Cotton,
1947
). The Yale University geographer Ellsworth Huntington
carried out sustained fieldwork in central Asia early last century and became well-
known for his vigorous espousal of environmental determinism, in which he argued
that human actions are determined by environmental and, ultimately, by climatic
changes (Huntington,
1907
; Huntington,
1945
).
In lieu of huge deserts and evidence of vast former pluvial lakes, India provided
evidence of a former flourishing urban civilization - the Indus Valley Culture - in the
form of the abandoned cities of Harappa and Mohenjo-Daro (Wheeler,
1968
; Allchin
and Allchin,
1982
). These Harappan settlements were often located on the banks of
now defunct river systems, prompting speculation about climatic desiccation, river
capture, tectonic displacement of drainage and Ayran invasions around 4,000 years
ago (Singh,
1971
; Singh et al.,
1974
; Misra,
1983
) (see
Chapter 12
).
Another feature of the Indian landscape is the presence of laterite, a soil or weath-
ering profile depleted of bases and silica and enriched in hydrated oxides of iron
and aluminium. First defined by Buchanan (
1807
, pp. 440-441) as a clay soil on the
