When studying the Earth’s rotation and magnetic field, information about geothermal heat often comes up. Apparently, molten metals such as iron flow in the Earth’s outer core, generating the geomagnetic field, and the Earth retains enough heat to keep the metal molten. Although we don’t often feel it in our daily lives, it seems that the Earth has geothermal heat of about 6,000 degrees inside, close to the surface temperature of the Sun.
https://www.enecho.meti.go.jp/category/resources_and_fuel/geothermal/explanation/development/
Geothermal energy is separate from the thermal energy from the sun. It is thought that geothermal heat is generated continuously by the heat generated when the radioactive nuclei of uranium, thorium, potassium, etc. decay, in addition to the heat generated when the earth was born. It takes a fairly long time, from 700 to 14.1 billion years for half of the amount of these elements to decay, to continue to generate heat.
https://grsj.gr.jp/archives/whatbook/chapter1.html
Thanks to this geothermal heat, rocks and metals are heated and rise, then cooled on the surface and fall, creating convection in the mantle, a rock layer. The mantle melts near the low-pressure ocean floor and turns into magma, which cools and creates plates from undersea mountain ranges, which continue to cool and sink down through deep ocean trenches. This is how materials circulate between the Earth’s surface and interior. It’s a magnificent cycle. Geothermal energy is amazing.
https://mtl-muse.com/study/kashio-spring/plate-and-volcano
I think the goal of circulation on the Earth’s surface is the ocean floor, including sand and mud that have flowed from land to the ocean floor, remains of marine life, and other materials that have sunk. The sediments on the ocean floor are carried by plates, and through the earth and geothermal heat, new water, carbon, and many rocks and minerals come to the surface. Volcanic ash, which is formed when magma cools and hardens, seems to enrich the soil and nurture life.
https://synodos.jp/opinion/info/17686
Hydrothermal vents, where heat and various substances spew from the ocean floor due to geothermal heat, are said to have a very high density of living organisms, forming independent ecosystems on the ocean floor where no light reaches. It’s amazing that there is an “ecosystem that eats the sun” that uses photosynthesis, and an “ecosystem that eats the earth” at hydrothermal vents on the deep ocean floor.
https://grsj.gr.jp/archives/ghts/symposium/020913seminar/naganuma.htm
The weight of the rocks from above keeps the underground under constant high pressure, and the geothermal heat keeps it at a high temperature. It is said that under this high temperature and pressure, minerals such as gold and diamonds may be formed, and oil may be produced from minerals and water. It is exciting to see how the underground is uncovered in the future.
https://www.sci.tohoku.ac.jp/news/20170302-8938.html
https://natgeo.nikkeibp.co.jp/nng/article/news/14/1520
We usually only feel geothermal heat when we go to hot springs, but geothermal heat is amazing because it creates the largest and most time-consuming cycle of matter. The Earth’s circulation is amazing.
