Plate Tectonics

Question 1

Density

Answer 1

density = mass/volume
if two substances of different densities come into contact and one is acting as a fluid, the substance with lesser density will float above the substance with greater density

Question 2

tectonic plates vs plate tectonics

Answer 2

TP - large subdivisions in the crust of the planet
PT - the study of the movement of TP

Question 3

Faults

Answer 3

major fracture in the continuity of two regions of rocks
all plate boundaries associated with faults but not all faults are associated with plate boundaries

Question 4

Oceanic Crust

Answer 4

density heavier than continental (2.9 - 3g/cm cubed)
uniform thickness
relatively young
mainly found oceans, but not always!

Question 5

Continental crust

Answer 5

lighter density than ocean crust
differences in thickness - very thick
varying ages - older than oceanic crust
generally found out of water, Zealandia continental crust below ocean)
cratons - oldest and most stable regions of continental crust

Question 6

Asthenosphere

Answer 6

below upper mantle and crust
hot enough that rock behaves like liquid

Question 7

How do tectonic plates move?

Answer 7

convection current = movement of liquid rock is driven by in temp. and density btwn outer and inner layers of mantle

Question 8

Push-pull process

Answer 8

Ridges - creation of new plates where magma rises
Subduction zones - Destruction of plates by crushing (pull down)
slab pull - entire plate pulled by the weight of its cold, dense sub ducting section

Question 9

Divergent boundary

Answer 9

seafloor spreading - process of tectonic plates moving apart at divergent boundaries, ridges
(where hot liquid rises from the asthenosphere)
brand new crust is hotter, less dense than then older, cooler crust – sinks!

Question 10

Hydrothermal Sea Vents

Answer 10

weak point in the sea floor where water and minerals heated geothermally enter the ocean, found at divergent boundaries

Question 11

Rift Valley

Answer 11

When divergent boundary can form on continental crust
rock formed here similar to oceanic crust, denser
eventually all rift valleys will be submerged under water

Question 12

How can we tell Magnetic Pole Reversals?

Answer 12

when lava rock solidifies, minerals which are magnetized in the rock lock into an orientation reflecting the existing direction of the magnetic field, and we can test this

Question 13

Convergent Boundary

Answer 13

Two plates moving towards each other, one plate will be forced under the other, into a subduction zone

Question 14

Ocean-continent convergent boundary

Answer 14

Ocean is forced under bc more dense, forms OCEANIC TRENCH
melts –> less dense –> rises to continental crust –> continental crust

Question 15

Ocean-Ocean

Answer 15

Oldest crust forced under, produces volcanic activity
responsible for many oceanic island chains

Question 16

Continent-Continent

Answer 16

One can be forced under the other, but they do not suduct, does not sink easily
force rocks up into new mountain ranges
if there is some oceanic crust beneath the continental crust, parts of oceanic crust can be moved to mountain tops (scapped up ocean sediment at top of Himalays)

Question 17

Transform Boundary

Answer 17

Plates slide paste each other
creates transform faults
cause earthquakes

Question 18

Elastic Rebound theory

Answer 18

plates cannot move continuously, energy and pressure builds up at the fault until it is released all at once in a sudden movement

Question 19

Supercontinent breakup and life

Answer 19

breakup produces predictable trends in climatic and topographic conditions
- increased biome and species diversity
- increased volcanic activity, global temp.
- shallow seas, sea levels rise

Question 20

Angle of insolation

Answer 20

angle at which sunlight hits planet
high concentration of solar energy and equator
less energy per surface area at higher or lower latitude

Question 21

Albedo

Answer 21

reflectivity of a surface
lighter substances have cooling impact
darker substances have a warming impact

Question 22

Tectonic Plates impact on life and Earth (3)

Answer 22

Snowball Earth bc they were all mainly at equator ~750MA
Global ocean currents transport heat, continents movement can redirect oceanic currents
glaciation + cooling temperature ~50MY

Question 23

Landform

Answer 23

natural feature of the physical landscape of the Earth

Question 24

Igneous rock

Answer 24

new rock formed from cooling of molten rock from the mantle, within crust or volcanic eruptions
how all minerals in the crust formed

Question 25

Metamorphic rock

Answer 25

minerals that have been changed from their original form through intense heat and pressure
takes place under the crust, or at convergent boundaries

Question 26

Sedimentary rock

Answer 26

rocks formed from the pieces of other rocks or organic material
pressure forces together lowest layers of material into a single structure –>forming a new mineral

Question 27

Physical Weathering

Answer 27

mechanical break-up of rock,
freeze-thaw cycle

Question 28

chemical weathering

Answer 28

mineral breakdown by chemical reaction, ex: weak acid

Question 29

biological weathering

Answer 29

tree roots breaking up rock, parrotfish eating dead corals, lichen using acids to breakdown rocks

Question 30

Erosion

Answer 30

material which has been weakened though weathering moved from its original location
sometimes very long distances as long as there is energy, when it ends = deposition leads to sedimentation

Question 31

The rock cycle

Answer 31

igneous is transformed to metamorphic or breaks down to sedimentary
metamorphic break down to
sedimentary
sedimentary can transform into metamorphic