Earth's Crust

Crust - Earth's relatively thin, rocky outer skin (continental crust and oceanic crust).
The oceanic crust is roughly 7 kilometers (5 miles) thick and composed of the dark igneous rock basalt.
The continental crust averages about 35 kilometers (22 miles) thick but may exceed 70 kilometers (40 miles) in some mountainous regions.
The upper crust has an average composition of a granitic rock called granodiorite.
Continental rocks have an average density of about 2.7 g/cm^3 and some have been found to be more than 4 billion years old.
Oceanic crust is younger (180 million years or less) and denser (about 3.0 g/cm^3).

Mantle

Mantle - A solid, rocky shell that extends to a depth of about 2900 kilometers (1800 miles) and takes up more than 82 percent of Earth's volume.
The upper mantle extends from the crust-mantle boundary down to a depth of about 660 kilometers (410 miles).
Lithosphere - Top portion of the upper mantle and is the stronger part. Consists of the entire crust plus the uppermost mantle and forms Earth's relatively cool, rigid outer shell. Averaging 100 kilometers in thickness, but 250 kilometers thick below the oldest parts of the continents.
Asthenosphere - Weak layer with a small amount of melting to a depth of 410 kilometers.
The lithosphere is able to move independently of the asthenosphere.
Transition Zone - From about 410 kilometers to about 660 kilometers in depth. Identified by a sudden increase in density from about 3.5 to 3.7 g/cm^3 because minerals in the rock peridotite respond to the increase in pressure by forming new minerals with closely packed atomic structures.
Lower Mantle - From a depth of 660 kilometers to the top of the core, at a depth of 2900 kilometers (1800 miles). The rocks within the lower mantle are very hot and capable of extremely gradual flow.

Earth's Core

Core - Thought to be composed of an iron-nickel alloy with minor amounts of oxygen, silicon, and sulfer with an average density of nearly 11 g/cm^3 and approuaches 14 times the density of water at Earth's center.
Outer Core - A liquid layer 2270 kilometers (1410 miles) thick. It is the movement of metallic iron within this zone that generates Earth's magnetic field.
Inner Core - a sphere with a radius of 1216 kilometers (754 miles). Despite higher temperatures, the iron in the inner core is solid due to the immense pressures.

Concept Checks

	Created by Jonathan Latiuk about 10 years ago

Geology 101 Latiuk (Lesson 1) Note on 1. An Introduction to Geology, created by Jonathan Latiuk on 13/10/2016.