1. Dimensions of the Earth

2. Shape and Composition of the Earth The Earth is close to being a perfect sphere. The Earth bulges slightly at the equator and flattens slightly at the poles. Evidence of the Earth’s shape? Ships “sink” when moving past the horizon Satellite photographs Moon phases and lunar eclipses Nearly equal gravitational attraction of objects all over the Earth’s surface. POLES: slightly flattened EQUATOR: slightly bulging The Earth is composed of a series of spheres. Each sphere has a different composition of materials and is held together by gravity. The spheres of Earth are arranged from least dense (atmosphere) to most dense (geosphere) depending on how close they are found to the Earth’s center.

3. Atmosphere The layer of gases that surround the Earth located above the Earth’s surface is known as the atmosphere. The atmosphere is the least dense of all the spheres The atmosphere is composed of 78% nitrogen,21% oxygen and 1% other gases and aerosols – suspended solids and liquids in the atmosphere. Earth’s atmosphere is broken down into smaller spheres (zones) with distinct differences in air temperature and composition. The interface between these zones are called pauses. RT = Pg. 14

4. Hydrosphere The layer of liquid water found at the Earth’s surface is known as the hydrosphere. The hydrosphere consists of bodies of freshwater and saltwater found on Earth’s surface including: oceans, lakes, rivers and streams. Mostof the hydrosphere(~7 0%) is composed of water (hydrogen/oxyg en).

5. Lithosphere The layer of rock that forms the outer shell of the Earth is known as the lithosphere. The lithosphere lies beneath the atmosphere and hydrosphere. The uppermost section of the lithosphere is the crust which is broken up into sections known as lithospheric or tectonic plates. RT = Pg. 1

6. Geosphere The region of the Earth between the crust and Earth’s center is known as the geosphere. The geosphere is the most dense of all the spheres RT = Pg. 10 The geosphere is broken into zones based on changes in density, pressure and temperature.