Download Denudational Processes and Weathering

CGF 3M0
Nov 12, 2002
Denudational Processes and Weathering
Landforms result from the uplift caused by tectonic forces and the processes of
denudation, or leveling, than are constantly at work to lower the earth’s
surface to a common level.
Uplift is powered by energy from below, while denudation is powered largely by
energy from above.
The processes of denudation work to reduce the land surface to base level, the
lowest level to which a land surface can be eroded.
Sea level is the ultimate base level, although there are some areas that are
below sea level
e.g. Death Valley, CA and the Dead Sea in Israel & Jordan
At the present rate of denudation of the earth’s surface, all the continents would
be worn down in 10 to 12M years (without constant uplift).
Degradation:
1. Weathering – the disintegration or decomposition of rocks in places
on or near the earth’s surface
2. Erosion – the removal and movement of rock debris and organic
matter
3. Transportation – carried out by wind, running water, ice, wave
action
Aggradation: involves the building up of the land surface by the deposition of
rock materials
1. Deposition – occurs when a drop in energy slows the transporting
agent to the point where it drops or deposits some of its rock materials
Denudational processes occur very slowly that they often go unnoticed.
However, some processes such as floods and landslides cause great death and
destruction in very short periods of time.
Weathering – reduces solid rocks to smaller and smaller particles. This
breakdown is important because without it erosive agents would be less
effective.
Two major sources of energy for the breakdown of rock materials are:
1. Solar Energy – powers chemical activity, the hydrologic cycle, and
winds
2. Gravitational Energy – brings down moisture as rain and causes
stream flow and other downhill movements