Physical Geology

Question 1

Geology

Answer 1

the study of the Earth
* physical geology is concerned with them materials and processes which compose and operate on the surface of, and within, Earth

Question 2

Principal subsystems of the earth

Answer 2

atmosphere
biosphere
hydrosphere
geosphere

Question 3

Plate tectonic theory

Answer 3

lithosphere is composed of rigid plates that diverge, converge, or slide sideways past one another as they move over the asthenosphere

Question 4

Uniformitarianism

Answer 4

forms a cornerstone of geology
* principle states that the laws of nature have remained unchanged through time and thus, that the processes observed today have also operated in the past, though possibly at different rates

Question 5

Plate movement is ____

Answer 5

the driving mechanism of the rock cycle

Question 6

Rock

Answer 6

a solid aggregate of one or more minerals, as well as non-crystalline matter such as natural glass or organic material like coal

Question 7

Igneous rocks

Answer 7

form from the crystallization of magma as it cools, from material that is thrown out of a volcano

Question 8

Intrusive igneous rock

Answer 8

crystallizes beneath the earth’s surface

Question 9

Extrusive igneous rock

Answer 9

crystallizes and cools at the earth’s surface.
* can form as glass or ash

Question 10

Sedimentary rocks

Answer 10

typically deposited in layers formed from:
* rock/mineral fragments
* precipitation of minerals from solution
* the compaction of plant and animal remains

Question 11

Metamorphic rocks

Answer 11

form from alteration of other rocks, usually by:
* heat
* pressure
* chemically active fluids

Question 12

The core

Answer 12

composed of iron and a small amount of nickel

Question 13

The asthenosphere

Answer 13

behaves plastically and flows slowly
* composed primarily of peridotite, an igneous rock made of olivine
* surrounds lower mantle
* partial melting generates magma

Question 14

The crust

Answer 14

• thick continental crust
• thin, denser oceanic crust

Question 15

The lithosphere

Answer 15

• crust and upper mantle make up the lithosphere
• forms the solid outer layers of the earth

Question 16

Plate tectonics is ____

Answer 16

the unifying theory of geology
* heat-transfer within the asthenosphere, moves the plates
* plates separate, mostly at oceanic ridges
* collide and are subducted into interior at oceanic trenches

Question 17

Alfred Wegener

Answer 17

proposed continental drift hypothesis
* however, failed to provide a convincing mechanism
* continents have moved in the past
* noticed that Africa and South America fit
* he postulated that all landmasses were
originally united into a supercontinent
named Pangaea

Question 18

Support of plate tectonics

Answer 18

• volcanism
• seismicity
• mountain building
• climatic changes
• animal and plant distributions
• distributions of natural resources

Question 19

Continental crust

Answer 19

• less dense
• much thicker than oceanic crust
• helps explain why mountains on land stand higher on continents than in ocean basins

Question 20

Continental crust floats

Answer 20

isostacy: crust floats in the denser mantle
* all crust is less dense than the mantle
* oceanic crust is denser and floats lower
* mountains are high because they are less dense

Question 21

Isostatic rebound

Answer 21

• glaciers melt or mountains erode away
• crust rises back up to equilibrium level
• rebound occurs slowly

Question 22

Divergent

Answer 22

form when plates move away from one another
* new oceanic lithosphere is forms at the
opening rift
* most occur along the crests of oceanic ridges
* also present under continents during the early stages of continental breakup

Question 23

Convergent

Answer 23

places where two plates collide
* oceanic-oceanic: is where two oceanic plates collide, one ocean plate will subduct beneath the margin of the other plate
* oceanic-continental: oceanic plate and a continental plate collide, the oceanic plate will subduct
* continental-continental: when two continents collide, neither plate will subduct

Question 24

Oceanic-oceanic convergent boundary

Answer 24

• one oceanic plate is subducted beneath the other
• a volcanic island arc forms on the non-subducted plate
• oceanic trench forms where the subduction is taking place
• the volcanoes result from rising magma produced by the partial melting of the subducting plate

Question 25

Oceanic-continental convergent boundary

Answer 25

• oceanic plate and continental plate converge
• denser oceanic plate is subducted under the continental plate
• chain of volcanoes forms on non-subducted plate
• oceanic trench forms

Question 26

Continental-continental convergent boundary

Answer 26

• when ocean floor separating continents is all subducted, continents converge
• results in a collision between the two continents
• neither plate will subduct
• continents are welded together to form an interior mountain chain

Question 27

Transform

Answer 27

• plates slide laterally (sideways) past each other along faults
• these boundaries change one type of motion between plates into another type of motion

Question 28

Hot spots

Answer 28

• a stationary column of magma, from deep within the earth
• has slowly risen to the surface and formed a volcano
• enable geologists to determine plate motion
• Yellowstone

Question 29

Mantle plumes

Answer 29

• remain stationary
• while plates move over them, trail of extinct and progressively older volcanoes that record the movement of the plate is left

Question 30

Mineral deposits

Answer 30

• many of the world’s major metallic ore deposits are associated with convergent and divergent plate boundaries
• hydrothermal activity, often volcanic

Question 31

Continental accretion

Answer 31

• process of adding material to a continent
• common along convergent oceanic-continental plate boundaries

Question 32

Mineral

Answer 32

• natural
• inorganic
• crystalline solid
• characteristic physical properties
• specific chemical composition

Question 33

Most common minerals are made up of ___, ___, and one or more other elements.

Answer 33

oxygen, silicon

Question 34

Silicate minerals

Answer 34

composed of the silica tetrahedra
most minerals are silicates (compounds of
silicon and oxygen, and other elements)

Question 35

Ferromagnesian silicates

Answer 35

made up of iron and or magnesium, combined with other elements
dark in color and dense
olivine and biotite

Question 36

Non-ferromagnesian silicates

Answer 36

lack iron and magnesium
light colored

Question 37

Carbonate minerals

Answer 37

all carbonate minerals have the carbonate radical (CO³)-² as in calcite (CaCO³) and dolomite [CaMg(CO³)²]
found mostly in the sedimentary rocks limestone and dolostone
carbonates are derived from the shells and hard parts of marine organisms or are precipitated from seawater as evaporites

Question 38

Native elements

Answer 38

composed of a single element
gold, copper and diamonds

Question 39

Sulfide minerals

Answer 39

contain sulfur plus a metallic element as in
galena (PbS) and pyrite (FeS²)
commonly form along mid-oceanic ridges

Question 40

Sulfates

Answer 40

have the sulfate radical (SO4 -²) as in gypsum (CaSO4 2H2O)
common in deserts, forming from evaporation of water

Question 41

Mineral cleavage

Answer 41

refers to the breakage or splitting of mineral crystals along one or more smooth planes determined by atomic structure

Question 42

Number of cleavages and direction
1
2 at right angles
3 at right angles
3 at not right angles
4
6

Answer 42

Cleavage name
micas (biotite)
prismatic - feldspars
cubic - halite and galena
rhombohedral - calcite and dolomite
octhahedral - fluorite and diamond
dodecahedral - sphalerite