Kathy Sullivan the first American woman to walk in space in 1984 became the first woman to reach to the Challenger Deep. Challenger Deep it the deepest part on seabed reaching more than 10.9 Km.
About Challenger Deep
Challenger Deep is an oceanic trench found in the western Pacific Ocean. It is the deepest part of Mariana Trench reaching as deep as about 10.9 Km (as per Wikipedia) so also the deepest part of earth. The trench is near the Mariana Island group.
How Trenches are Formed
The answer to this question is found in the famous theory of Geography i.e. Plate Tectonic Theory, propounded in 1960s. This theory was a result of combined study of many scientists like – Wilson, Mckenzie & Parker etc. This theory utilizes two major scientific concepts – continental drift and sea floor spreading.
As per plate tectonic theory, the Earth surface (Crust) is divided into various lithospheric plates. These plates float over the semi-molten rock surface call aesthenosphere. During the plate movement, plates can diverge – i.e. go away from each other or can converge – i.e. come towards each other or can slide past each other.
During the convergence movement of lithospheric plates, the plate which is has higher density subducts beneath the light plate. The subduction process give rise to deep trenches.
In the case of Mariana Trench – the lithospheric plate of Pacific Ocean is subducting beneath the lithospheric plate called “Philippines Plate” so forming deepest part of the seabed.
Why Trenches are Important
Oceans still remains one of the least explored part of the Earth and so trenches being the deepest part of earth surface (seabed) provide an important source of deep oceanic exploration, behaviour of life at such depth, study of interior of Earth, deep sea mineral composition & knowledge about seismic activity, tsunami etc.
Other Important Trenches
Aleutian trench (Near Bering Sea – about 7.8 Km deep); Kuril Trench (North-East of Japan’s Hokkaido Island, about 10.5 Km Deep); Japan trench (east of Japan – about 10.5 Km deep); Mariana trench (South of Guam, about 10.9 Km); Mid Indian Ridge – middle of Indian Ocean; Southwest Indian Ridge – separates Africa and Antarctic plates; Java trench (south of Indonesia) etc.
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