Environmental Engineering Reference
In-Depth Information
negatively correlated with the mobility of the scree (i.e. the smaller the debris, the more
mobile is the scree). The free face scree system is called a
morphological system
; it is
still essentially descriptive and shows the network of structural relationships operating
between the free face, the scree and the size of the scree material.
In the introduction, the term
factor
is used for any control which leads to an effect. A
process
is any transformation (physical, chemical or biological) which the environment is
experiencing or has experienced in the past. Thus the weathering of Carboniferous
Limestone in Upper Wharfedale is a general process of rock breakdown carried out by a
series of specific weathering processes (i.e. freeze-thaw, root quarrying, leaching,
chelation
,
carbonation
). The speed at which the processes operate is governed by
several key factors such as temperature, frost cycles, rainfall amount, rainfall acidity,
vegetation type and amount, and by the rate of removal of weathered material by slope
and soil processes to expose fresh limestone rock. Processes in physical geography
involve the movements of energy and/or matter through a series of interconnected
subsystems. The
output
of one subsystem provides all or part of the
input
of another
subsystem. The movement of water from its input in precipitation through to the channel
of the river Wharfe and its tributaries forms a
cascading system
(Figure 1.5). Water
circulates through a number of stores (atmospheric store, vegetation store, surface store,
soil moisture store, groundwater store) before being removed by outputs of evaporation,
transpiration or drainage discharge.
Figure 1.4
The morphological system of free faces and
associated screes.
Source: After Chorley and Kennedy (1971).
