Describe earth crust?

The Earth's crust is the outermost layer of the Earth, ranging in thickness from about 5 to 70 kilometers (3 to 44 miles). It is composed of a variety of rocks, minerals, and sediments, and is divided into several tectonic plates that float on the semi-fluid mantle beneath. The crust is constantly changing due to processes such as erosion, volcanic activity, and tectonic plate movement. It is also where most of Earth's geological activity occurs, including earthquakes, volcanic eruptions, and the formation of mountains and valleys.