The inner core of the Earth is composed of solid iron; this iron is the main heat source of the Earth and is the driving force behind the many essential systems that make up the Earth. The heat from the inner core is slowly being lost mainly due to the formation of ridges on the ocean floor. The inner core also transfers heat to the outer core which is necessary in order to cater for another fundamental process of the earth. The outer core forms one of the most integral parts of the Earth’s functioning as it drives the magnetic field. The convection of the liquid in the outer core is the mechanism through which the magnetic field is generated.
The mantle also plays a critical role in the functioning of the Earth. Convective overturn of the mantle is the main source that drives the plate tectonic system at the surface. The mantle is divided into two parts, the inner mantle and the outer mantle. The inner mantle is composed of solid rock due to the extreme pressures the rock is subjected to. The outer mantle is further divided into the bottom layer and top layer, both of which are composed of iron and magnesium.
As mentioned earlier, the mantle plays a critical role in the driving of the plate tectonic system. Convection is the critical process that occurs in the mantle, heat from the core is transferred through the layers up to the crust, on its way to the crust it starts cooling down, as it starts cooling it starts moving horizontally along the bottom of the crust before eventually subsiding. This process is cyclic and has been unfolding for billions of years. When convection currents strike a weakness in the Earth’s crust such as a volcano or a oceanic ridge, magma is released and replaces the old layer. When the earth’s crust is under tensional forces the crust will become much thinner than normal, if there is no fault. This means that the crust becomes weaker as it is thinner than normal. This can happen to the oceanic crust in the ocean basins, but will only cause an earthquake with a hot spot. A hot spot is an abnormal hot rising area of the mantle that supplies the lava for volcanoes. If at the same time a hot spot is directly below a thinned crust then the magma in the hot spot may hold too much pressure to be held by the thinner weakened crust. If this is the case then the magma can penetrate the lithosphere, and eventually erupt on the surface. The action of the magma forcing its way up can trigger earthquakes as it breaks through the crust. When its breaks through the crust at the sea bed eventually a volcanic island will be formed in the middle of the ocean. A subduction zone is where two plates collide and one is forced below the other, they occur at convergent boundaries. They collide because of compression forces, pushing them into each other. One plate is subducted below the other into the mantle, where it will be recycled. An example can be seen by the subduction of the Pacific plate under the Eurasian plate.
The collision of the Pacific and Eurasian plates causes a massive build up of pressure, as time progresses this pressure forces one of the plates (Pacific) to start bending downwards. However the plate does not slip, just bends. This is because of the friction between the two plates is enough to allow them to bend, without slipping. This is a very slow but continuous movement, maybe only a few millimetres every year. Every fraction moved by the plates increases the build-up of elastic strain energy within the rock. The rock continues to store this energy from a few decades to a few thousand years. An earthquake will happen when the strain in the rocks exceeds that of the limit of the rocks. The fault then ruptures, moving a large distance in a short space of time. The plates then snap back into a new position, forcing the already undercutting plate to dive down even further under the other. The collisions of two plates generally produce large forces in the plates. These processes are vital in ensuring the recycling of the Earth’s rocks. In short, Oceanic crust is continually being formed along the mid oceanic ridge via the mechanism of sea floor spreading; this oceanic crust is then ultimately, subducted back into the earth’s mantle and recycled. The entire surface of the Earth is in constant motion which was a necessary discovery in explaining and developing the theory of plate tectonics which in turn is used to explain the formation of the continents.
The inner Earth is not the only part of the Earth that allows for the sustainment of life, the processes that occur in the biosphere and at the surface also influence and affect life. For example the oceans play a pivotal role in the regulation of Earth’s climate, warm oceans generally bring low pressures and more temperate and humid conditions compared to the climatic conditions that are bought by cold oceans which are characterized by high pressures and more drier and cold conditions.
Plants and other primary producers also form an integral part of life on the planet as they generate a huge amount of oxygen through the process of photosynthesis. Photosynthesis is a particularly vital process as not only does it result in the production of oxygen but also the absorption of carbon dioxide for the atmosphere. Excess carbon dioxide in the atmosphere is enhancing the onset of global warming which is a factor that could be potentially problematic in ensuring the survival of humanity. According to Monbiot carbon emissions must be kept below 450 parts per million as any excess over this amount will alter global temperatures by as much as two degrees Celsius, such a substantial increase will severely change global climates and therefore disrupt contemporary life as we know it (Monbiot,2007). He goes on further to say that a ‘global cut of 90% is needed by 2030 in order to ensure that levels do not exceed 450 parts per million which is necessary in order to prevent another mass extinction’ (Monbiot, 2007).
The ozone layer in recent times has also been affected by the changing chemistry in the atmosphere. In some places holes have developed in the layer which is a major concern as the ozone layer plays an important role in regulating the amount of sunlight that enters the Earth. Weaknesses in the ozone layer enhance the onset of global warming as the increased sunlight prevents carbon dioxide and other greenhouse gasses from escaping back into the atmosphere thus resulting in the warming of the planet.
The Earth is an amazing place that is perfect for sustaining life. Our position in the solar system as well as the all the complex and dynamic processes that occur on the planet all interrelate in order to provide the perfect setting for the facilitation of life and make the Earth the habitable planet that we live in today. However, we must be careful not to abuse this amazing place that we have been given and in order to ensure future survival we must strive to accentuate the pros of sustainable development and the implementation of legislature and quotas that will reduce and control carbon emissions. By being proactive and taking a stand everyone has the ability to reduce his/her carbon footprint which is a necessity in reducing our impact on the environment, this can be achieved through the use of public transport or fitting catalytic converters or installing solar panelling. However in order to drastically reduce our global carbon footprint more radical measures need to be taken, these include the development of alternative forms of power such as wind, bio fuel, solar and nuclear power (Monbiot:,2007).
Bibliography
Monbiot, G. (2007). Heat: How to Stop the Planet from Burning. South End Press 2007.
