Environmental Engineering Reference
In-Depth Information
Plate 13.1
The '3000 ft' remnant summit plateau of Y
Glyderau, north Wales, which was probably once a lowland
plain. Ridge-push forces, as the Atlantic continued to widen,
elevated it tectonically by 1 km less than 25 Myr ago, in the
mid-Cenozoic era.
Photo: Ken Addison.
landform assemblages led to the creation of morphogenetic maps (Figure 13.3). At first
sight they are plausible, especially since glacial and hot desert environments equate with
modern climatic zones. Climate inconstancy and tectonic displacement of crust across
climatic zones cannot be ignored, however. Many landforms are
polygenetic
, formed by
more than one process. Close affinities with climate also recede when we consider that
many Pleistocene glacier landsystems now lie outside the glacial zone and are reminders
of fluctuating climate patterns. Many landforms are not specific to any one climatic zone.
Slopes and fluvial channels evolve in all climates, and coastlines and mountains are
distinctly azonal. Details of form or intensity which reflect climatic nuances do not
override this principle. No one doubts the role of climate in contributing materials (water,
ice, air, pollutants) in particular amounts and regimes to the geomorphic environment, or
of temperature and moisture, etc., in influencing processes. To regard it as dominant or
controlling is inappropriate, however: it ignores the role of geological factors and
misunderstands the nature of
process
.
Force
and
resistance
hold the key to the progressive breakdown of intact rock and
therefore denudation. Forces
