The Lithosphere

The solid, outer portion of the earth

The lithosphere is the solid, outer part of the earth - its rigid upper mantle. The main features of the lithosphere are the continental plates. The earth's surface is subject to constant change ranging from dramatic changes to changes so small they are not visible over a human lifetime.

Geomorphology is the study of landforms, their origin, evolution, type and distribution

Continental Drift

Wegener's theory of continental drift suggests that the currently isolated continents shifted laterally from a former "supercontinent". At first, scientists rejected the theory until plate tectonics were proven to be true. The discovery of the asthenosphere is very significant to the theory of plate tectonics as the lubrication layer assisting plate movement explained how the plates were able to move.

Gradational Processes

  • Weathering - the in situ (on site) physical disintegration and chemical decomposition of rocks and materials at or near the earth's surface.
  • Chemical Weathering - involves the actual decomposition of rocks, primarily by means of exposure to water, oxygen and carbon dioxide.
  • Physical Weathering - slow breaking up of rocks of the land surface into smaller particles (but no chemical composition change)
  • Mass Movement - the downslope movement of weathered rock material under the influence of gravity.
  • Erosion - the wearing away of land by running water, rainfall, wind, ice or other geological agents

SINKHOLES

How Scary Sinkholes Are Formed

A sinkhole is essentially any hole in the ground created by erosion and the drainage of water. Although they're often the result of natural processes, they can also be triggered by human activity. They mainly occur on 'karst terrain'; areas of land where soluble bedrock is dissolved by water. This causes the bedrock beneath the earth's crust to ultimately erode, until it collapses and the overburden above it collapses into it as well, causing sinkholes up to 30 metres or even kilometres deep.

Soil

Soils are a complex mix of inorganic minerals, air, water and organic matter. It provides foundation for plant life.

Soils are developed by 2 processes:

  1. Water causing physical and chemical weathering
  2. Biological processes
The 4 characteristics of soil are:
  • Texture: size of soil particles
  • Structure: soils with a high clay content cling together, sandy soils do not
  • Colour: dark = high humus content
  • Acidity & Alkalinity: affects plant growth
Source of image: http://www.thegef.org/gef/greenline/december-2012/dirt-matters-investing-soil-ecosystem-services-global-environment-and-food-s
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Human Interactions

The lithosphere is at risk of developments in agriculture, mining, forestry, industry, urban settlement, tourism and infrastructure.

Land Degradation - the decline in the quality of natural land resources