INTRODUCTION
What is Geomorphology?
- one approach = understanding, explaining, describing LANDSCAPES.
Landscapes are collections of landforms - morphological features on the surface
of the Earth e.g. cliffs, ridges, valleys, beaches... etc.
These landforms are made of the solid or weathered rock that makes up the
earth's surface.
Geomorphology includes the study of the evolution of landforms over time,
as well as contemporary processes that are presently creating landforms.
In theory, there is a GEOMORPHOLOGICAL explanation for every feature on the
surface of the Earth - for example, if an area is flat there should be a reason
why it is flat; a steep cliff exists because of some reason - landforms do not
occur randomly or by chance: the question is, what are the reasons landforms
appear the way they do?
Our approach is based on the following:
1. Rocks at the surface
of the earth are UNSTABLE - they all wear away eventually.
2. Initial
conditions at the surface are not equal - some parts of the surface are higher
than others (e.g. mountains); and different
rock types occur in different areas.
3. To change the shape of the earth's surface requires energy - where energy
expenditure is high, erosion occurs and erosional landforms are created; where
energy expenditure is low, deposition occurs, creating depositional landforms.
4. Most landscapes
take a long time to develop - contemporary processes may not alone explain
landforms; often the history of the landscape must also be studied.
The course is organized to reflect these principles:
PART I. STRUCTURES - THE
RESISTIVE FRAMEWORK
Deals with the initial
shape of the surface. This section of the course deals with initial conditions
at the surface - the shape of the surface imparted by tectonics, volcanism and
diastrophism.
PART II. MATERIALS - THE
RESISTIVE ELEMENTS
Rocks and soils - the
ability to resist change depends on strength.
PART III. PROCESSES -
AGENTS OF ENERGY EXPENDITURE
The ability to change the
shape of the surface depends on the movement of material - this requires energy;
sources include:
Gravity - energy due to
height and the pull of gravity...
Running water - energy
due to the movement of water in rivers
and streams...
Waves - energy due to the
movement of water in lakes and
oceans...
Ice - energy due to
moving glaciers….
PART IV. HISTORY
Many landscapes retain
landforms formed during the last Ice Age - the past must often be reconstructed
to explain the present.
Applied Geomorphology:
The last part of the
course presents case studies of applied geomorphological research, dealing with
coastal erosion and sedimentation in Texas.