GHC Ch 2: Internal Energy and Plate Tectonics Flashcards
What is Nebula Theory?
Theory that the solar system began as rotating spherical cloud of gas, ice, dust and debris. Cloud contracted, sped up and flattened into disk.
Describe the formation of Sun.
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.
Describe the formation of the planets. What happened to the inner planets versus the outer planets?
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.
Describe the impact origin of the Moon.
Early impact of Mars-sized body with Earth left cloud of debris which condensed into the Moon.
What did Earth begin as and when?
An aggregating mass of particles and gases nearly 4.6 billion years ago.
What are the 4 processes of planet formation that created huge amounts of heat?
Impact energy, decay of radioactive elements, gravitational energy, and the differentiation into layers.
Describe Earth’s differentiation into layers.
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.
Describe Earth 4.4, 3.5, 2.5, and 1.5 billion years ago.
- 4 billion years ago: large oceans, small continents
- 5 billion years ago: life (earliest photosynthetic bacteria?)
- 5 billion years ago: larger continents
- 5 billion years ago: plate tectonics, for sure!
What is the state of the inner core? (solid, liquid, gas?)
Inner core is solid.
What is the state of the outer core? (solid, liquid, gas?)
Outer core is liquid and has viscous convection currents.
What is responsible for Earth’s magnetic field?
The outer core.
How thick is Earth’s mantle?
2,900 km thick
Describe the mantle’s composition.
Stony
The mantle takes up how much of Earth’s volume and mass?
83% and 67%
What has happened to Earth’s low-density elements?
They have been ‘sweated’ out of the mantle to form the crust, atmosphere and oceans.
Layers can be described in terms of…
Different density (different chemical and mineral compositions), or different strength.
List the layers of the Earth in order. (2)
Atmosphere, hydrosphere, lithosphere, asthenosphere, mesosphere, outer core, inner core. OR crust, mantle, core.
Lithosphere
Rigid layer (solid rock).
Asthenosphere
Fluidlike layer (plastic rock).
Mesosphere
The solid mantle below asthenosphere.
What are the 6 volcanic gases?
Hydrogen (H), oxygen (O), carbon (C), sulfur (S), chlorine (Cl), nitrogen (N)
What is the dominant volcanic gas? How much of volcanic gas is this gas?
water vapor, 90%
What are the 7 elements of volcanic rocks?
Oxygen (O), silicon (Si), aluminum (Al), iron (Fe), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K)
4.5 billion years of volcanism has brought light weight elements to the surface to make up…
Continents, Oceans, Atmosphere, CHON (carbon, hydrogen, oxygen, nitrogen; elements of life)
Elastic deformation
recoverable – object returns to original shape.
Ductile deformation
is permanent – stress applied over long time or at high temperatures. Think putty.
Brittle deformation
permanent – stress applied very quickly to shatter or break object.
Rocks at Earth’s surface… brittle or no?
(low temperature, low pressure): brittle
Rocks in asthenosphere… brittle, or no?
“soft plastic”
Where does the asthenosphere come to the surface? How deep is it under the surface elsewhere?
at mid-ocean ridges, 100 km
What does the asthenosphere do?
Allows continents to ‘float’ atop the mantle, by principles of isostasy
