![]() The research efforts eventually led to the proper identification, sampling, and mapping of trenches via sonar. During World War II, the widespread use of echo sounders led to rapid developments in marine research, especially in the western Pacific Ocean. In 1939, this hypothesis was further developed by Griggs and, in later years, by the well-known American geologist Harry Hammond Hess. Based on his findings of ‘belts of negative gravity anomalies’ close to island arcs, he proposed the “tectogene hypothesis.” During the 1920s and 1930s, the noted Dutch geodesist Felix Andries Vening Meinesz used the gravimeter to measure gravity over the trenches. In 1923, Johnstone, in his book “An Introduction to Oceanography,” first used the term ‘trench’ in its truest modern sense. In the late 19 th and 20 th centuries, the laying of transatlantic telegraph cables between the continents also stressed the need for improved ocean bathymetry. The 1872 to 1876 Challenger Expedition discovered “Challenger Deep” at the Mariana Trench’s southern end. History Of The Term “Trench” A diagram showing the Puerto Rico Trench.īefore the Challenger Expedition, the ocean’s bathymetry was not well-known, and the trenches were also not very clearly defined. The greatest ocean depth has been measured at the Challenger Deep - the lowest point of the Mariana Trench, reaching a depth of about 35,830 ft below sea level. The deepest oceanic trenches in the world include the Mariana Trench in the western Pacific Ocean, the Philippine Trench in the east of the Philippines, the Tonga Trench near Tonga, the Kermadec Trench to the northeast of New Zealand, and the Kuril-Kamchatka Trench near the Kuril Islands. Featuring a characteristic V-shaped profile, the trenches are placed on the island arcs’ oceanward side and the Andean-type orogenic belt. ![]() km, i.e., only 0.5% of the world’s oceans. There are estimated to be more than 50 significant ocean trenches worldwide, occupying an area of 1.9 million sq. Oceanic trenches are found in the deepest ocean areas at maximum oceanic depths ranging between 24,000 to 36,000 ft, mainly at subduction zones on convergent plate boundaries. Where Are Oceanic Trenches Found? Map showing the location of the world's deepest trench, the Mariana Trench. However, in recent years, concerns have been raised regarding the accumulation of plastic debris in the oceanic trenches, posing a severe threat to these unique biotic communities. The oceanic trenches form a part of the ocean’s hadopelagic zone and feature exclusive biomes based on chemotrophic microorganisms adapted to the region’s extreme environmental conditions. ![]() Approximately 31,000 miles of oceanic trenches are known worldwide, the majority of which are placed around the Pacific Ocean, some in the eastern Indian Ocean, and just a few in the Mediterranean Sea and the Atlantic Ocean. Oceanic trenches are a distinctive feature of the Earth’s plate tectonics and are found at convergent boundaries, where two or more tectonic plates move towards each other at rates varying from a few millimeters to more than 10 cm yearly. Also referred to as “deep-sea trenches,” oceanic trenches are conspicuous, deep, narrow, steep sloping depressions on the ocean floor.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |