welcome to moomoomath in science in this video let's take a look at the layers of the earth based on chemical composition and physical properties the earth can be divided into three layers based on chemical composition the crust the mantle and the core the outermost layer of the earth is called the crust there are two types of crust continental and oceanic the crust averages around 25 miles of 40 kilometres in thickness and can be divided into 15 major tectonic plates that are rigid in the center and have geological activity at the boundaries such as earthquakes and volcanoes the Earth's crust contains all three rock types including igneous sedimentary and metamorphic oceanic crust lies under the ocean and is thin and is approximately four miles or seven kilometres in thickness and it's composed of dense rocks including basalt continental crust is thicker and ranges from 6 to 47 miles or 10 to 75 kilometers in thickness inhibiter has a high abundance of less dense igneous rock like granite the mantle is located between the crust and the core it's a region of hot slow-moving solid rock the mantle is 1,800 miles thick or 2,900 kilometers and it's composed of silicate minerals and they're similar to the ones found in the crust except with more magnesium and iron unless silicon and aluminum the core extends from below the mantle to the center of the earth scientists believe the core is made mostly of iron and nickel the core is the densest layer and makes up about 1/3 of the Earth's mass the outer core is composed mostly of iron and nickel with metals found in liquid form the outer core reaches temperatures of 7,200 to 9,000 degrees Fahrenheit and it's estimated to be about 1,400 miles thick or 2300 kilometers the inner core is the hottest part of our planet and has temperatures between 9,000 and 13,000 degrees Fahrenheit it's a solid layer and it's around 755 miles or 1,200 kilometers thick and it's composed mostly of iron this iron is under so much pressure that it stays as a solid the earth can also be divided into layers based on physical properties such as whether the layer is solid or liquid the five physical layers are the lithosphere asthenosphere mesosphere outer core and inner core the outer most rigid later the earth is that lithosphere the lithosphere is around 100 kilometers thick and it's divided into tectonic plates the earth list of the sphere includes the crust in the upper part of the mantle and it is hard and rigid outer layer of the earth the asthenosphere lies underneath and it's made of solid rock that moves very slowly it's described as this so elastic which means it can flow and also can be elastic the asthenosphere is located below the lithosphere and the tectonic plates move on top of the asthenosphere the strong lower part of the mantle is called the mesosphere rock in the mesosphere flows more slowly than rock in the asthenosphere the outer core is the liquid layer of the Earth's core and the inner core is the solid part the inner core extends from the bottom of the outer core to the center of the earth thanks for watching and moomoomath uploads a new math and science video every day please subscribe and share