News - Researchers find explanation for emergence of mysterious bulges, depressions on Earth's surface

The constant movement of Earth’s tectonic plates reshapes our planet on a daily basis, but deep mantle processes also play a role, recent research shows, reports The Guardian. Many of Earth’s most significant features sit on plate boundaries: mountain ranges such as the Himalayas appear where continental plates collide; volcanoes and ocean trenches like those around the Pacific Ocean occur where ocean plates dive beneath continental ones.  But our planet also has many surface features that sit far from tectonic plate boundaries and cannot be explained so easily. To better understand these mystery features, researchers compared crustal thickness data with mantle measurements, to identify locations where differences in the temperature and chemistry of the mantle were likely to be creating bulges and basins on Earth’s surface. Their findings, published in the Journal of Geophysical Research: Solid Earth, show that areas where the mantle is hot produce some of the largest bulges (up to 2km high and stretching across hundreds of kilometers), such as the Afar-Yemen-Red Sea region, western North America, and Iceland. Meanwhile, cool mantle regions produce deep basins such as those found around the Black, Caspian and Aral seas, and in the East European Plain. Such features develop slowly over millions of years but are fundamental to geological processes such as erosion and sedimentary deposition.