The Composition AND Structure of the Earth

Composition of the Earth The Earth is made up of 3 main layers: Core Mantle Crust Mantle core The layers are based on compound(s) – a substance composed of two or more elements Crust

The Crust The thin and solid outermost layer above the mantle 5 – 100 km thick It is the thinnest layer of the Earth Less than 1% of Earth’s mass Crust

The Crust Continental Crust thicker Oxygen, silicon, aluminum, iron, calcium, and magnesium Oceanic Crust thinner, but MORE dense Almost twice as much iron, calcium, and magnesium

The Mantle The layer of rock between the crust and the core Much thicker and contains most of the Earth’s mass; roughly 2/3 or 67% The mantle has more magnesium and less aluminum and silicon than the crust It is more dense than the crust

The Core The central part of the Earth below the mantle Scientist believe the Earth’s core is made mostly of iron and contains smaller amounts of nickel, but almost no oxygen, silicon, aluminum, or magnesium It makes up roughly 1/3 (33%) of the Earth’s mass. It is more dense than the crust

Layers of the Earth Song!

Physical Structure

Physical Structure Lithosphere: outermost, solid/rigid layer made up of the crust and the rigid upper part of the mantle divided into pieces called tectonic plates Asthenosphere: The soft layer of the mantle on which the tectonic plates move Solid rock that flows very slowly

Physical Structure Mesosphere: The strong, lower part of the mantle Between the asthenosphere and the outer core Outer Core: Liquid layer of the Earth’s core Between the mantle and inner core Inner Core: Solid, dense center of the Earth

If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle.

Plate Tectonics Pieces of the lithosphere that move around on top of the asthenosphere The Earth’s crust is divided into 10-12 major plates which are moved in various directions. This plate motion causes them to collide, pull apart, or scrape against each other. Each type of interaction causes a characteristic set of Earth structures or “tectonic” features. The word, tectonic, refers to the deformation of the crust as a consequence of plate interaction.

World Plates

Physical Structure How do scientists know the inside of the Earth? Seismic waves traveling through the Earth The waves travel at different speeds due to density in the layers of the Earth Waves travel faster through solids than liquids Seismographs measure the waves This information can track thickness and density of each physical layer