The planet Earth is composed of many layers. The first layer and the outermost zone is the crust. It is composed of a great variety of igneous, metamorphic, and sedimentary rocks. The temperature varies from place to place. Earth's crust is between three and 46 miles deep. The thickest parts are under the continents and the thinnest parts are under the oceans. Beneath the crust is the mantle. It has a temperature range between 800 and 1600 degrees Celsius. It is made of a very thin layer of rock and is mainly molten. Last is the core which is divided into two parts; the outer core and the inner core. Its temperature is between 3000 and 5000 degrees celsius. It is mainly made up of iron and nickel.