Earth Systems Interior of Earth Earth Basics 71

Earth Systems: Interior of Earth

Earth Basics • ≈ 71% Earth’s surface covered with H 2 O • Slightly flattened sphere “oblate spheroid” • Surface is fairly smooth • 3 rd planet (rock) from the sun • 5 th largest planet (12, 756 km diameter) • Gravity – force of attraction between matter (6 times greater than the moon!)

Earth’s Interior

Earth’s Interior • Properties determined by changes in speed and direction of seismic waves – Seismic waves are vibrations that travel through Earth

Compositional Zones: • Crust – thin outermost layer of Earth above the mantle • Oceanic Crust – beneath the oceans (5 -10 km thick) • Continental Crust – makes up the continents (15 – 80 km thick) • Mantle – layer of rock between the crust and core • Core – central part of Earth below the mantle composed of Iron and Nickel

Compositional Zones

Structural Zones: • Lithosphere – solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle • Asthenosphere – solid, “plastic like” layer of the mantle which can flow and move the tectonic plates above it • Mesosphere – the middle sphere, strong, lower part of the mantle, made of solid rock

Structural Zones: • Outer Core – dense liquid of iron and nickel • Inner Core – dense rigid solid of iron and nickel

Earth is Magnetic • Two magnetic poles create magnetic field surrounding Earth • May be caused by movement of liquid iron in outer core – Sun and moon have magnetic fields but sun has no iron and moon has no liquid outer core • As liquid moves, electric currents create magnetic field

Earth’s Magnetic Field