👉 Understrata is a concept in physics and earth science that refers to the lowermost layer of the Earth's crust, which is characterized by its high density and low permeability. It is composed of rocks, minerals, and other materials that are less dense than the surrounding layers of rock. The understratum is responsible for the formation of tectonic plates and the movement of land masses on Earth. Understrata is also known as the "soft" or "plastic" layer of
