The Geosphere
Changes occur on the Earth constantly: Molten rock flows from volcanoes Hurricanes batter beaches and change coastline Earthquakes shake the ground
The Earth is a system that consists of air, water, rock and living things All of the ‘parts’ interact with each other
Scientists use special terms to describe the different parts of the Earth Geosphere – consists of all the rock, soils and sediments on the Earth Atmosphere – consists of the air that surrounds the Earth Hydrosphere – consists of all water, fresh or saltwater Biosphere – all living things on the planet
Most of the geosphere is located in the Earth’s interior The average diameter of the Earth is 12,756km
Discovering the Earth’s Interior
The earth is like an onion Its made of layers
The information we have concerning the interior of the Earth comes to us from studying seismic waves Seismic waves travel through different material at different rates. When seismic waves change direction or speed, it means they have moved through different layers
Scientists divide the Earth into three layers based on composition Crust – the thinnest layer of the Earth (5-20km thick) made entirely of light elements Mantle – makes up 64% of the earth’s mass, (2900km thick) made of rocks of medium density Core – has a radius of 3400km and composed of the densest elements
The Earth can also be divided into 5 layers based on physical properties Lithosphere Asthenosphere Mesosphere (mantle) Outer core Inner core
The lithosphere is the Earth’s outer layer It contains the crust and uppermost part of the mantle and is divided into moving sections called Tectonic Plates
The asthenosphere is the layer beneath the lithosphere The asthenosphere is the ‘plastic’ solid layer of the Earth that the plates move on top of
The mesosphere consists of the lower mantle between the asthenosphere and outer core The mesosphere contains molten rock which is called ‘magma’
The outer core is 2200km thick and made of nickel and iron The outer core is mostly liquid
The inner core is a solid sphere of iron, nickel and cobalt (radioactive) The temperature of the inner core is thought to be between 4000 and 5000 degrees Celsius
Scientists believe that cobalt in the core decays producing heat The heat from the core produces energy that makes the magma move producing earthquakes, volcanoes and plate movement