Geology Reference
In-Depth Information
1
Introduction to tectonic
geomorphology
Introduction
rivers and glaciers are incising into bedrock and
the rates at which landslides are stripping
mountain slopes. Clearly, the merger of such
data sets can underpin a new understanding of
the balance between the rates at which crustal
material is added at a given site and the rates at
which this material is eroded away. Defining
this balance and interpreting the landscape that
results from this competition represents a major
component of modern tectonic geomorphology.
One of the remarkable attributes of tectonic
geomorphology is the breadth of fields it often
encompasses. Few other geological fields easily
blend as disparate topics as seismology, Quaternary
climate change, geochronology, structure, geod-
esy, and geomorphology. In fact, such breadth
makes this field particularly exciting, as new data
and ideas emerge from fields as diverse as
paleobotany and fault mechanics. This diversity
also presents a formidable challenge, because
successful studies commonly require blending
of appropriate data from specialized fields that
were traditionally considered to be unrelated.
Certainly, specialists in well-established disciplines
like structural geology or stratigraphy often make
important contributions to tectonic geomorphol-
ogy. Fundamental leaps in our understanding,
however, more commonly emerge from an
integration across several disciplines.
This topic is intended primarily for readers
who are familiar with basic geomorphological
and structural concepts and terms. Although we
The unrelenting competition between tectonic
processes that tend to build topography and
surface processes that tend to tear them down
represents the core of tectonic geomorphology.
Anyone interested in the Earth's surface has
wondered why it has the shape it does and what
forces are responsible for that shape. For more
than a century, this natural curiosity has inspired
numerous conceptual models of landscape
evolution under varied tectonic and climatic
regimes. In the past, our ability to assign reliable
ages to geomorphic and tectonic features was
commonly very limited. In the absence of a
chronological framework, testing competing
concepts of landscape evolution was nearly
impossible. As a consequence, these unquanti-
fied models were often viewed skeptically and
treated as speculative notions.
During the past few decades, innovative appli-
cations of new techniques for determining the
ages of landscape features, for assessing the
mechanisms and rates of geomorphic processes,
and for defining rates of crustal movement, have
helped revitalize the field of tectonic geomor-
phology. It is now possible to measure at the
scale of millimeters how rapidly a given site is
moving with respect to another and how those
rates of relative convergence or divergence are
partitioned among various faults and folds.
Similarly, we can now quantify how rapidly
