Geoscience Reference
In-Depth Information
ent material, and can create a high water table at the base of the slope and in valley or
basin sites. A sequence of soil types, formed on the same parent material but differing
in drainage according to their position on a slope, has been called a soil, or drainage,
'catena'.
Figure 11
shows two variants of such catenas, which are widespread features
of soil variation on a local scale.
F
IG. 11
The relationship between soil class and drainage to landform (Adapted from C.C. Rudeforth and others
1984.)
Among biological factors, some direct effects of vegetation and organisms on
soil profiles are considered in
chapter 7
. In an intensively settled and agriculturally
developed country like Britain, man has had an important effect on the course of soil
development everywhere at some time or another, and has remained a major influence
through historic time in lowland Britain. The evidence of soil change on abandoned
arable land in Wiltshire, also described in
chapter 7
, is one example of man's influen-
ce. Another is the way drainage, and, to a lesser extent, irrigation, rapidly alters the
moisture regime in a soil. In such circumstances, profile characteristics of a formerly
poorly drained soil can persist, even though the conditions that produced these charac-
