The term 'EARTH'S OUTER LAYER' can be summarized as the Earth's CRUST. The Earth's CRUST is the outermost layer of the Earth, composed of solid rock and soil. It is the thinnest layer of the Earth, ranging from 5 to 70 kilometers in thickness. It is composed of several different layers, including the upper CRUST, lower CRUST, and mantle. The CRUST is the source of many of the Earth's natural resources, such as minerals, oil, and gas.