GHC Ch 2: Internal Energy and Plate Tectonics

Question 1

What is Nebula Theory?

Answer 1

Theory that the solar system began as rotating spherical cloud of gas, ice, dust and debris. Cloud contracted, sped up and flattened into disk.

Question 2

Describe the formation of Sun.

Answer 2

Accumulation of matter (H and He). Temperature at center increased to 1 million degrees. Nuclear fusion of hydrogen (H) and helium (He) began, producing solar radiation.

Question 3

Describe the formation of the planets. What happened to the inner planets versus the outer planets?

Answer 3

Rings of concentrated matter formed within disk. Inner planets (Mercury, Venus, Earth and Mars) lost much gas and liquid to solar radiation, becoming rocky (terrestrial). Outer planets retained gas and liquid, as gas planets.

Question 4

Describe the impact origin of the Moon.

Answer 4

Early impact of Mars-sized body with Earth left cloud of debris which condensed into the Moon.

Question 5

What did Earth begin as and when?

Answer 5

An aggregating mass of particles and gases nearly 4.6 billion years ago.

Question 6

What are the 4 processes of planet formation that created huge amounts of heat?

Answer 6

Impact energy, decay of radioactive elements, gravitational energy, and the differentiation into layers.

Question 7

Describe Earth’s differentiation into layers.

Answer 7

Iron melted and sank below the rock and formed inner and outer core. Remaining rock melted, allowing low-density material to rise. Low-density material formed crust, oceans and atmosphere.

Question 8

Describe Earth 4.4, 3.5, 2.5, and 1.5 billion years ago.

Answer 8

4. 4 billion years ago: large oceans, small continents
5. 5 billion years ago: life (earliest photosynthetic bacteria?)
6. 5 billion years ago: larger continents
7. 5 billion years ago: plate tectonics, for sure!

Question 9

What is the state of the inner core? (solid, liquid, gas?)

Answer 9

Inner core is solid.

Question 10

What is the state of the outer core? (solid, liquid, gas?)

Answer 10

Outer core is liquid and has viscous convection currents.

Question 11

What is responsible for Earth’s magnetic field?

Answer 11

The outer core.

Question 12

How thick is Earth’s mantle?

Answer 12

2,900 km thick

Question 13

Describe the mantle’s composition.

Answer 13

Stony

Question 14

The mantle takes up how much of Earth’s volume and mass?

Answer 14

83% and 67%

Question 15

What has happened to Earth’s low-density elements?

Answer 15

They have been ‘sweated’ out of the mantle to form the crust, atmosphere and oceans.

Question 16

Layers can be described in terms of…

Answer 16

Different density (different chemical and mineral compositions), or different strength.

Question 17

List the layers of the Earth in order. (2)

Answer 17

Atmosphere, hydrosphere, lithosphere, asthenosphere, mesosphere, outer core, inner core. OR crust, mantle, core.

Question 18

Lithosphere

Answer 18

Rigid layer (solid rock).

Question 19

Asthenosphere

Answer 19

Fluidlike layer (plastic rock).

Question 20

Mesosphere

Answer 20

The solid mantle below asthenosphere.

Question 21

What are the 6 volcanic gases?

Answer 21

Hydrogen (H), oxygen (O), carbon (C), sulfur (S), chlorine (Cl), nitrogen (N)

Question 22

What is the dominant volcanic gas? How much of volcanic gas is this gas?

Answer 22

water vapor, 90%

Question 23

What are the 7 elements of volcanic rocks?

Answer 23

Oxygen (O), silicon (Si), aluminum (Al), iron (Fe), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K)

Question 24

4.5 billion years of volcanism has brought light weight elements to the surface to make up…

Answer 24

Continents, Oceans, Atmosphere, CHON (carbon, hydrogen, oxygen, nitrogen; elements of life)

Question 25

Elastic deformation

Answer 25

recoverable – object returns to original shape.

Question 26

Ductile deformation

Answer 26

is permanent – stress applied over long time or at high temperatures. Think putty.

Question 27

Brittle deformation

Answer 27

permanent – stress applied very quickly to shatter or break object.

Question 28

Rocks at Earth’s surface… brittle or no?

Answer 28

(low temperature, low pressure): brittle

Question 29

Rocks in asthenosphere… brittle, or no?

Answer 29

“soft plastic”

Question 30

Where does the asthenosphere come to the surface? How deep is it under the surface elsewhere?

Answer 30

at mid-ocean ridges, 100 km

Question 31

What does the asthenosphere do?

Answer 31

Allows continents to ‘float’ atop the mantle, by principles of isostasy