What is the Geosphere?
The geosphere is the Earth itself, the rocks, minerals, and landforms of the surface as well as its interior. Below the crust, which varies from about 5 km beneath the ocean floor to up to 70 km below the land surface, temperatures are high enough for deformation and a paste-like flow. At one time, roughly 200 million years ago, the continents were joined together in a supercontinent called Pangaea, but since then the tectonic plates have slowly separated, creating the arrangement of the continents we are accustomed to today.
Plate tectonics is ongoing and humans can witness its sometimes violent activity in the form of earthquakes and volcanoes. More regularly, however, human interaction with the dynamic geosphere comes in the form of surface erosion, our use of arable land for farming, and excavations for the construction of buildings, roads, and mines.
How does the geosphere interact in the Earth system?
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Evolution of the continents.
Fast-forward 200 million years from the time of Pangaea to the creation of the modern-day continents.
(Credit: ARC Science Simulations)
While seemingly static, the geosphere is in fact a very active player in the Earth system, affecting the atmosphere and the oceans, as well as critical processes such as the water cycle and the biogeochemical cycles. For instance, the types of minerals contained in soils--a factor of geologic processes--help to determine the vegetative cover and ecosystems at the surface. Carbon – an essential element of life – is bound in organic matter and is carried to the ocean via wind and water erosion where eventually it becomes part of the ocean floor. Tectonic movement carries the ocean deposits into the Earth's interior. On geologic timescales, volcanic activity can vent the carbon to the Earth's atmosphere as carbon dioxide. The carbon cycle is one of the key cycles linking the geosphere, atmosphere, hydrosphere, and biosphere.
The outer core of the Earth contains liquid iron. Its motion is thought to drive the Earth's magnetic field – the magnetosphere - which extends far beyond the atmosphere protecting Earth and its biosphere from solar wind and cosmic radiation.
How do humans interact with the geosphere?
Soy Plantation, Amazon Brazil. With the aid of fossil fuel-powered machinery, man can make sweeping changes to the natural landscape. In Brazil, for instance, the drive to produce more and more soybeans for food and biofuels leads to deforestation of the Amazon rainforest.
Aside from surface disturbances such as excavations and agriculture, humans have a fairly minor impact on the workings and scale of the geosphere. Humans still live largely at the mercy of powerful geologic forces. The 2010 Haiti earthquake is just one of many examples of the devastating impact of these forces. While we may never be able to stop earthquakes or volcanoes, our understanding of their mechanics may enable us to better understand their dynamics and possibly develop means for reducing human risk from their occurrences. Additionally, advances in geothermal technology will enable us to harness greater amounts of heat energy within the crust, which can be converted to electricity at the surface.