Relationships between Rock Structure and Topography
The landform features that result from tectonic activity vary
from microscopic fractures to major mountain ranges. However, few of these remain in their original form because of the
leveling action of degradation and aggradation. It is important to note the difference between surface topography
(landform features) and the structural arrangement of the
rocks (rock structure), as shown in Figure 14.36. For instance,
the limb of an anticline may form a surface ridge, but it can
also form a valley because of erosional activity on weak or
broken rocks. Some mountain tops in the Alps are the erosional remnants of synclines, which are structural downfolds.
As another example, Nashville, Tennessee, occupies a topographic valley, yet it is sited in the remains of a structural
dome (a circular, domed, anticline). An important distinction
is that the terms mountain and ridge refer to surface landforms
(topography), whereas the terms anticline and normal fault signify rock structures, which may or may not be visible at the
surface. It is also important to remember that the topographic variation on Earth’s surface has resulted mostly from
three major factors: the interaction among forces that act to
create relief, the gradational processes that operate to shape
landforms and reduce relief, and the relative strength or resistance of different rock types to degradational processes.
