Physical Geology: Chapter 1&23 (introduction to geology & earths companions)

Question 1

geology

Answer 1

is a science that studies the origin and evolution of Earth and solar system bodies

Question 2

geocentric model

Answer 2

model that places Earth at the center of the solar system

Question 3

heliocentric model

Answer 3

model that places the Sun at the center of the solar system

Question 4

differentiation

Answer 4

• the process through which the Earth transformed into a different planet with a zoned interior (the crust, the mantle, and the core)
• partial melting or complete melting of earth allowed heavier more dense minerals and elements like: iron (Fe) & nickel (Ni) to sink to down a produce the core; also allowed the reverse, lighter less dense minerals and elements like: silicates, and plagioclase feldspar
• the energy to partially/completely melt the earth came from:
  1) impacts; and 2) radioactive decay

Question 5

The Core

Answer 5

• inner most zone of the Earth
• gravity, seismic, and geochemical data strongly suggest its mostly made up of iron
• core molten on outside (ouster-core) and solid on the inside (inner-core) where the pressures are highest (5200 to 6400 km in depth)

Question 6

The Mantle

Answer 6

• is material in the middle zone
• makes up the bulk of solid earth
• seismic and geochemical data strongly suggest is has an intermediate density and is formed mostly of compounds of O2 with Mg, Fe, and Si
• about 40 to 2900km in depth

Question 7

The Crust

Answer 7

• materials that floated toward the surface of magma ocean formed Earths solid crust
• thin outer layer up to about 40 + Km thick
• contains relatively light materials with low melting temperatures
• most easily melted compounds are Si, Al, Fe, Ca, Mg, Na, and k

Question 8

Earth has two heat engines

Answer 8

• internal: (comes from the initial formation of Earth and form radioactivity)
• external: (comes from sun a.k.a. solar energy)

Question 9

Internal Energy

Answer 9

• drives volcanism and other interior processes

Question 10

External Heat

Answer 10

• energizes the atmosphere and oceans which are responsible for climate and weather

Question 11

Earths surface: 1) the continents

Answer 11

• its not clear what caused the initial formation of the continents; hypothesis :
  1) repeated melting and solidification of initial cooled surface: allowed lighter elements to become separated form heavier ones and float to surface

Question 12

2) oceans and atmosphere

Answer 12

• origin traceable to water and gases that boiled off during initial heating/ differentiation of earth (water, H, N, C initially bound in minerals , then freed by partial melting, carried to surface by magmas and then released through volcanic activity)
• gases released from volcanos in early Earth history are believed to have been the same as those released today in modern volcanoes
• today the atmosphere is mostly made up of N and O, but O apparently only persisted in atmosphere after photosynthetic algae developed and began releasing substantial O was a waste product

Question 13

Earth is composed of a system of interacting components

Answer 13

1) heat from interior drives mantle convection
2) solar energy drives most of biosphere and atmosphere
3) interactions between atmosphere, hydrosphere, biosphere, geosphere

Question 14

Lithosphere

Answer 14

• (crust and upper mantle): strong, solid, outermost shell; 100-200 Km thick; cool and brittle with roughly a dozen of plates

Question 15

Asthenosphere

Answer 15

• weak layer upon which lithosphere rides; weak because its almost at melting point; 100 to 200 Km thick and can also flow

Question 16

Earths age

Answer 16

• about 4.5 billion years old