1. Dimensions of the Earth

2. Shape and Composition of the Earth 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 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 known 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 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 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 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.