Geology Reference
In-Depth Information
3
GEOMORPHIC MATERIALS
AND PROCESSES
Weathering, erosion, transport, and some soil processes create sediments and soils. This chapter covers:
sediment production by weathering
sediment transport by gravity, water, wind, the sea, and ice
sediment deposition
humans as geomorphic agents
Geomorphic footprint
After the Earth had evolved a solid land surface and an atmosphere, the water cycle and plate tectonic processes
combined to create the rock cycle. Weathering, transport, and deposition are essential processes in this cycle. In
conjunction with geological structures, tectonics processes, climate, and living things, they fashion landforms and
landscapes. Over the last two centuries or so, humans have had an increasingly significant impact on the transfer
of Earth materials and the modification of landforms, chiefly through agricultural practices, mining and quarrying,
and the building of roads and cities. As Harrison Brown (1956, 1031) commented:
A population of 30 billion would consume rock at a rate of about 1,500 tons per year. If we were to assume that all the land areas of the
world were available for such processing, then, on the average, man [
sic
] would “eat” his way downward at a rate of 3.3 millimeters per
year, or over 3 meters per millennium. This figure gives us some idea of the denudation rates that might be approached in the centuries
ahead. And it gives us an idea of the powers for denudation which lie in mankind's hands.
The 'geomorphic footprint' is a measure of the rate at which humans create new landforms and mobilize sediment
(Rivas
et al
. 2006). For four study areas - one in northern Spain and three in central and eastern Argentina - new
