Earth Inside and Out Key Ideas How is

Earth: Inside and Out

Key Ideas • How is the Earth’s interior structured? • How has the appearance of the Earth changed over time? • What geologic Features are common near tectonic plate boundaries?

Where did the Earth come from? • http: //www. mnh. si. edu/earth/main_frames. ht ml

Geologic Time • http: //www. eram. k 12. ny. us/education/compon ents/docmgr/default. php? sectiondetailid=17500 &fileitem=6776&catfilter=449&PHPSESSID=f 7 224 dbc 8 e 13359 ed 2 bb 68 e 998 eed 97 a

Earth’s Interior • Three parts: 1. Crust 2. Mantle 3. Core

Crust • Only makes up 1% of Earth’s mass. • Continental crust averages about 12 -25 miles deep. • Oceanic crust averages about 3 -5 miles deep.

Mantle • • • Lays beneath the crust. Denser than the crust. Makes up 80% of the Earth’s interior. About 1800 miles deep. Humans have never drilled all the way to the mantle.

Core • • • Core makes up 19% of Earth’s mass. Composed mainly of iron and nickel. Two layers – inner and outer core. Inner core – solid metal Outer core – liquid metal • http: //www. mnh. si. edu/earth/main_frames. ht ml

Hot, Hot!!! • The temperature of the Earth increases with depth. • The Earth’s interior contains radioactive isotopes. • As uranium, thorium and potassium decay, they release energy that is stored in the core.

Plate Tectonics • Alfred Wegener hypothesized that all of the continents might have been part of one landmass in the past before they drifted apart.

Plate Tectonics • The continents fit together like pieces of a puzzle. • The landmass was called Pangaea.

Plate Tectonics • Fossil record showed that the continents were at one time, one landmass.

Plate Tectonics • How did the continents get to their current location? ? ?

Continental Drift • Continental Drift Theory is theory that the Earth’s surface is made up of large moving plates.

• http: //www. ucmp. berkeley. edu/geology/tecall 1 _4. mov

Continental Drift • Where’s the evidence? • Changing magnetic fields discovered on either side of the Mid-Atlantic Ridge. • Suggests that the crust was moving away from the plate boundary in both directions.

Continental Drift • Lithosphere = crust + upper portion of mantle • Lithosphere is made up of 8 large plates(and 9 smaller plates) called tectonic plates. • Tectonic plates move from 1 -10 cm per year.

What makes tectonic plates move? • Hypothesis One – convection currents in the asthenosphere , the hot, plastic portion of the mantle moves the plates. • Hypothesis Two – plates are driven by the force of gravity acting on their own massive weight.

• http: //www. mnh. si. edu/earth/main_frames. ht ml