Planet Earth Earths Formation The earth formed by

Planet Earth

Earth’s Formation • The earth formed by accretion of dust and small objects in the early solar system. orbital motion – Heat from collisions – Melt and reform collision • Earth rocks are compared to meteorites and moon rocks. different orbit

Layers in the Earth • Heating the earth caused the heavy metals to sink and lighter minerals to rise. inner core outer core mantle crust

Seismic Waves • Earthquakes near the surface create vibrations. – P waves compress – S waves shake, slower • Waves can be measured at surface points far away. – Interior information

Core • The earth’s core consists of iron and other metals. – 3500 km radius • Radioactivity keeps it hot. – Temperature to 6500 K – Liquid metal outer core • Density keeps part solid. – Solid within 1200 km – Pressure over 1 million atmospheres U Colorado

Mantle • Lighter minerals congregated above the core. – Silicates: silicon, aluminum, magnesium, oxygen – Iron, too • The mantle is solid, but plastic. – Slow movement, like putty under pressure. crust mantle outer core convection

Crust • The crust is the cool, hard surface of the mantle. – ocean - more dense, basalt rock – continents - less dense, granite rock • The crust is very thin; 10 km out of 6400 km radius. crust mantle outer core ocean floor continent

Plate Tectonics • Motion in the mantle causes the crust to split. – Earthquakes, mountains, volcanoes • Plate tectonics causes continents to move over millions of years. crust mantle overriding plate descending plate outer core ZME Science

Hot Plumes • The heat from the outer core causes molten rock to rise through the mantle. – Surface rises • The dense rock causes gravity to be very slightly higher. crust mantle outer core bulge at the surface plume

Volcanism • Plumes that push material to the surface form volcanoes. • Gases and minerals in volcanoes tell us about the earth’s mantle. crust mantle outer core volcano plume