Chapter 7 Section 1 Inside the Earth
Compositional Layers of the Earth (Brown) (Gray/green)
Composition of the Earth: • The Earth is divided into 3 compositional layers: • Core: • iron, nickel • Mantle: • magnesium, iron, aluminum, silicon, oxygen • Crust: • oxygen, silicon, aluminum, iron, calcium, & magnesium • Crust and mantle are not very dense. • Core is denser than the crust & mantle.
CRUST • The outermost layer • 5-100 km thick • Thinnest layer • 2 types of crust • Continental- thick • Oceanic-thin
MANTLE • 2900 km thick • Layer between the crust and core • Thicker than crust • Contains most of Earth’s mass • Scientists study the mantle by looking at the composition of magma. • Magma from volcanoes gives scientists clues about the composition of the mantle.
How scientists see the mantle • Volcanic eruption of Mt. Etna in Sicily
CORE • Innermost layer, below mantle to center of Earth • Made mostly of iron and nickel • Divided into two parts • Inner core—solid • Outer core—liquid
Physical Properties of Earth: How the layers respond to heat and pressure • Earth divided into 5 physical (mechanical) layers: • Lithosphere • Asthenosphere • Mesosphere • Outer Core • Inner Core
Lithosphere • Outer layer of Earth • Made of crust & rigid, upper mantle (asthenosphere) • Divided into pieces called tectonic, or continental plates • Continental plates drift slowly—a few centimeters a year—on top of the mantle
Asthenosphere • Layer below lithosphere • Pieces of lithosphere (tectonic plates) move along this layer • Made of solid rock, soft, plastic-like layer of the mantle
Mesosphere • Below the asthenosphere • Strong lower part of mantle • Extends to the Earth’s core
Outer Core • Liquid layer of Earth’s core • Surrounds inner core
Inner Core • Solid dense center
Quiz • 1. What are the three compositional layers of the Earth? • 2. What are the physical layers of the Earth? • 3. Is the mantle solid or liquid? • 4. What physical and compositional layers of the Earth do you live on?
Quiz Answers • 1. What are the three compositional layers of the Earth? Crust, Mantle, and Core (CMC) • 2. What are the physical layers of the Earth? • Lithosphere, Asthenosphere, Mesosphere, Outer Core, and Inner Core • 3. Is the mantle solid or liquid? Liquid that can be forced to act as a solid • 4. What physical and compositional layers of the Earth do you live on? • Physical: lithosphere Compositional: Crust