Causes Of Mass Extinction In Earth's History

Throughout the 5 mass extinctions in earth’s history, some general causes can be concluded. They are generally related to the earth’s environmental changes. The earth is a system run by 4 spheres. The hydrosphere, atmosphere, geosphere and biosphere is interrelated. Any impacts or significant changes and activities of a sphere would affect the other and finally resulting in mass extinction events shaping the earth into a different appearance.

General factors causing mass extinctions can be classified into 2 groups, catastrophic cause and gradual cause, where catastrophic causes are big massive events that can cause mass extinction in 1 single event and gradual causes are long term events which usually results from catastrophic events that

Several supercontinents were believed to exist in earth’s history. Pangea and Gondwana are the 2 that happened during the 5 mass extinction events. The combination and separation of continents closes oceans and may open another new ocean change the topography greatly as well as the climate. Although the change happened in a very long time (billions of years), volcanism and magmatism related can cause disastrous effect to lives on earth. Activities of the supercontinents often follows with extra active volcanism period. Massive flow of lava flooding the land would cause the elimination of habitats and lives. Massive amount of volcanic ashes erupted to the atmosphere would again block sunlight leading to a short cooling period. Then gases like carbon dioxide and sulfur dioxide would enhance global warming and acidify oceans causing another destructive gradual impact to both terrestrial and marine lives. Record of massive flood of magma can usually be proved by geological findings. Central Atlantic magmatic province (CAMP) which is an area of basaltic igneous rock is believed formed during a massive basalt flood that happened at the end of Triassic period which was believed causing the Triassic – Jurassic mass

Glaciation is believed to be a result of plate tectonics and is often related to continental drift. When continents are separated by tectonic movements, it often leads to blockage of ocean currents and therefore a gradual cause which is cooling climate that in turn leads to sea level decline and increase in ice coverage. In late Ordovician, the southern part of supercontinent Gondwana covering the South Pole led to formation of ice cap. As ice cap expands, more water will be locked on land which in turns drives a gradual change of decline of sea level. This causes a massive impact to marine lives where their habitable spaces decline leading to extinction of species. In Ordovician where most lives are living in water, this would lead to a mass extinction. Various evidences were found by now to prove the presence of ice age and glaciation. For example fossils of cold adapting organisms found in low latitudes, fragment of rocks brought to other places by glaciers, deposition of glacial tills, etc. It is rather convincing that glaciation and ice age existed in earth’s