Mountain environments - Environmental Sedimentology - page 37

Geomorphology

Fig. 2.3 Research
themes in mountain
geomorphology
(Barsch & Caine 1984).
Environmental
sedimentology is largely
focused on the
morphodynamics of
mountain environments
but has important links
to mountain form.
(Reproduced with
permission Mountain
Research and
Development .)

Mountain
geomorphology

Mountain
form

Morphodynamics
in mountains

Morphometry
and structure

Relief generation
and history

Morphoclimatic
models

Process dynamics
and activity

that are of greatest interest and in particular
the process dynamics and activity, because this
is what is most closely related to sedimentary
processes. Process dynamics, however, can never
be viewed in isolation because these are closely
controlled by morphoclimatic factors as well
as morphometry, structure and relief. Environ-
mental sedimentology, therefore, embodies the
full range of research themes in mountain geo-
morphology and in the case studies that follow
each of these themes is covered.

from mountain catchments (Church & Ryder
1972). Caine (1974) provided an early over-
view of alpine geomorphological processes
and described these as a series of sediment flux
cascades. This consisted of two dynamic geomor-
phological subsystems, namely the slopes and
stream channels (Fig. 2.4). Caine (1984) subse-
quently developed this concept by superimpos-
ing three sediment subsystems: the geochemical,
the fine sediment and the coarse detritus. This
basic description was later modified by Barsch
& Caine (1984) into a four-way classification of
mountain processes each with different controls,
responses and rates of activity.
Barsch & Caine (1984) distinguished:
• valley glacier sediment system
• coarse debris system
• fine sediment system
• geochemical system
All four systems interact and material is trans-
ferred between the different systems and hence
it is often convenient to couple some of these
systems together. For example, the valley glacier
and coarse sediment subsystems are most char-
acteristic of mountain areas of greatest elevation
and relief. Table 2.3 provides examples of these
subsystems and the main morphological units
which typify them.
Interactions between the coarse sediment sys-
tem and fine sediment system in many mountain
environments are difficult to separate as zones
of activity are closely coupled. For example, there

2.2

SEDIMENT SOURCES AND TRANSFER PROCESSES

2.2.1 The mountain sediment cascade

An important conceptual model in understand-
ing the environmental sedimentology of moun-
tain environments is the notion of the mountain
sediment cascade (Caine 1974). In simple terms
this depicts the mountain sediment system as
a series of sediment stores linked by a series of
transfer processes (Fig. 2.4). Recognizing and
quantifying significant sediment stores and the
processes that link them is the basis of the
sediment budget approach. The seminal work
by Rapp (1960) working in the Kärkevagge
catchment in Sweden used this methodological
approach and inspired others to follow a similar
approach in identifying the significance of sedi-
ment storage in regulating the sediment yield