Geoscience

Question 1

Layers of the Earth’s interior

Answer 1

Crust
Mantle
Outer core
Inner core

Question 2

Plate tectonics

Answer 2

Aka the geological Grand Unifying Theory

• describes how plates and continents contained by them are pushed and pulled around the surface of the earth
• explains processes that build mountains
• explains patterns of distribution of earthquakes and volcanoes

Question 3

Three types of tectonic plate boundaries

Answer 3

Convergent (colliding)
Divergent (spreading)
Transform (sliding)

Question 4

Convergent boundary outputs

Answer 4

Oceanic-oceanic
- volcanic island chains

Continental-oceanic
- mountain ranges along edge of continent
- oceanic plate is always subducted below (oceanic crust is denser)

Continental-continental
- mountain ranges

Question 5

Rocks

Answer 5

Naturally occuring aggregates of minerals

*manmade objects are never considered rocks or minerals

Question 6

Mineral

Answer 6

A naturally occuring homogenous solid with a definite (but generally not fixed) chemical composition and a crystalline structure

Formed by inorganic processes

*manmade objects are never considered rocks or minerals

Question 7

Gemstone

Answer 7

A valuable mineral that originated from an original source rock

Exceptions
- broadly, any mineral highly valued for its beauty, durability, and rarity
- can include non-minerals (organic or biological origin), eg. pearl, amber
- can include some rocks

Question 8

Relationship between rocks, minerals, and gemstones

Answer 8

Rocks = aggregates of minerals
Gems = highly valued minerals (and some non-mineral materials)

Question 9

Igneous rock

Answer 9

Crystallizes when molten material (melt/magma) cools

• rock is composed of interlocking crystals
• can be volcanic/extrusive or plutonic/intrusive

Question 10

Volcanic/extrusive rock

Answer 10

Rock formed from melt cooling at the surface of the Earth

Question 11

Plutonic/intrusive rock

Answer 11

Rock formed from melt cooling and solidifying inside the Earth

Question 12

Metamorphic rock

Answer 12

Formed by the alteration of pre-existing rocks

Rock transformation involves heat and/or pressure, and often fluid percolating through subsurface; does not involve melting

• compression can generate heat
• compression often results from plate collision
• pressure and temperature increases with depth
• newly generated minerals may be more stable at new temperature/pressure conditions

Question 13

Sedimentary rock

Answer 13

Physical - erosion
- weathering forms clastic sedimentary rock (eg sandstone, siltstone, mudstone –> fragments and grains of eroded rock)

Chemical - precipitation
- evaporite formed when body of water evaporates to form layers of salt

Biological - precipitation
- production of coral reefs, sediments composed of shells, and deposition of plant material in swamps (forms coal)

Question 14

Diagenesis/lithification

Answer 14

Processes that physically cements sedimentary grains together

Involves heat, pressure, and percolating fluids (like metamorphism), but not to the extent of drastic transformation of mineralogy or structure

Question 15

Rock cycle

Answer 15

Rock in mantle –> magma

Magma –> igneous rock (solidification)

Igneous rock –> metamorphic rock -or- sediment (weathering and erosion)

Metamorphic rock –> sediment -or- magma (partial melting)

Sediment –> sedimentary rock (lithification)

Sedimentary rock –> sediment -or- metamorphic rock (metamorphism)

Question 16

The Earth system

Answer 16

Atmosphere and oceans
Biosphere
Lithosphere
- crust (rigid)
- upper mantle (ductile)
- lower mantle (ductile)
Core (mantle boundary)
- fluid outer core
- solid inner core

Question 17

Lithosphere

Answer 17

Rigid layer composed of the crust and uppermost part of mantle

• contains tectonic plates

Question 18

Asthenosphere

Answer 18

Upper mantle just below lithosphere

• soft, lubricating layer over which tectonic plates move