Geology Reference
In-Depth Information
accepted even before Lyell's death, and non-actualism
and, in particular, catastrophism are discussed in geo-
morphological circles.
with dating techniques. Geomorphology has engaged
in methodological debates over the extent to which the
present is a key to the past and the rates of Earth surface
processes.
SUMMARY
ESSAY QUESTIONS
Geomorphology is the study of landforms. Three
key elements of geomorphology are land form, geo-
morphic process, and land-surface history. The three
main brands of geomorphology are process (or func-
tional) geomorphology, applied geomorphology, and
historical geomorphology. Other brands include tec-
tonic geomorphology, submarine geomorphology, plane-
tary geomorphology, and climatic geomorphology. Form
is described by morphological maps or, more recently, by
geomorphometry. Geomorphometry today uses digital
elevation models and is a sophisticated discipline. Armed
with a powerful combination of predictive models, field
observations, and laboratory experiments, process geo-
morphologists study geomorphic processes in depth.
They commonly use a systems approach to their subject.
Form systems, flow or cascading systems, and process-
form or process-response systems are all recognized.
Negative feedback and positive feedback relationships
are significant features in the dynamics of geomorphic
systems. The great achievements of process geomor-
phology include notions of stability, instability, and
thresholds in landscapes, the last two of which belie
simplistic ideas on cause and effect in landscape evo-
lution. Uncertainty surrounds the issue of geomorphic
process rates. Magnitude and frequency impinge on
part of this uncertainty. At first it was believed that
medium-magnitude and medium-frequency events did
the greatest geomorphic work. Some studies now sug-
gest that rare events such as immense floods may have
long-lasting effects on landforms. Land-surface history
is the domain of the historical geomorphologist. Some
early historical work was criticized for reading too much
into purely morphological evidence. Nonetheless, his-
torical geomorphologists had some great successes by
combining careful field observation with the analysis
of the sedimentary record. Historical geomorphologists
reconstruct past changes in landscapes using the meth-
ods of environmental and stratigraphic reconstruction
or topographic chronosequences, often hand in hand
1 To what extent do process
geomorphology and
historical geomorphology
inform each other?
2 Discuss the pros and cons of a
'systems approach' in
geomorphology.
3 Explain the different types of
equilibrium and non-equilibrium
recognized in geomorphic systems.
FURTHER READING
Ahnert,
F.
(1998)
Introduction to Geomorphology
.
London: Arnold.
A good starting text with many unusual examples.
Bloom, A. L. (1998)
Geomorphology: A Systematic Anal-
ysis of Late Cenozoic Landforms
, 3rd edn. Upper Saddle
River, N. J., and London: Prentice Hall.
A sound text with a focus on North America.
Goudie, A. S. (ed.) (1994)
Geomorphological Techniques
,
2nd edn. London and New York: Routledge.
Covers the topics not covered by the present topic - how
geomorphologists measure form and process.
Kennedy, B. A. (2005)
Inventing the Earth: Ideas on
Landscape Development Since 1740
. Oxford: Blackwell.
A good read on the relatively recent history of ideas about
landscape development.
Ritter, D. F., Kochel, R. C., and Miller, J. R. (1995)
Pro-
cess Geomorphology
, 3rd edn. Dubuque, Ill., and London:
William C. Brown.
A good, well-illustrated, basic text with a fondness for
North American examples.
