Page 33 - Fundamentals of Geomorphology

16 INTRODUCING LANDFORMS AND LANDSCAPES

Channel Valley-side slope Interfluve

Wind erosion and deposition
Waste mantle
Waste mantle

Debris
Debris Debris
production
transport production
Debris
Debris
production
production
Debris
Weathering front
Weathering front
transport

Uplift or subsidence
Figure 1.7 A hillslope as a system, showing storages (waste mantle), inputs (e.g. wind deposition and debris production),
outputs (e.g. wind erosion), throughputs (debris transport), and units (channel, valley-side slope, interfluve).

export matter or energy. A closed system has bound- destroy it. The events between the creation and the final
aries open to the passage of energy but not of matter. An destruction are what fascinate geomorphologists.
open system has boundaries across which energy and Systems are mental constructs and have been defined
materials may move. All geomorphic systems, including in various ways. Two conceptions of systems are impor-
hillslopes, may be thought of as open systems as they tant in geomorphology: systems as process and form
exchange energy and matter with their surroundings. structures, and systems as simple and complex structures
(Huggett 1985, 4–5, 17–44).

Internal and external system variables Geomorphic systems as form and process
structures
Any geomorphic system has internal and external vari-
ables. Take a drainage basin. Soil wetness, streamflow, Three kinds of geomorphic system may be identified:
and other variables lying inside the system are endoge- form systems, process systems, and form and process
nous or internal variables. Precipitation, solar radiation, systems.
tectonic uplift, and other such variables originating out-
side the system and affecting drainage basin dynamics 1 Form systems. Form or morphological systems are
are exogenous or external variables. Interestingly, all geo- defined as sets of form variables that are deemed to
morphic systems can be thought of as resulting from interrelateinameaningfulwayintermsofsystemori-
a basic antagonism between endogenic (tectonic and gin or system function. Several measurements could
volcanic) processes driven by geological forces and exo- be made to describe the form of a hillslope system.
genic (geomorphic) processes driven by climatic forces Form elements would include measures of anything
(Scheidegger 1979). In short, tectonic processes create on a hillslope that has size, shape, or physical prop-
land, and climatically influenced weathering and erosion erties. A simple characterization of hillslope form is