Earth's Changing Face: The Basics of Plate Tectonics (L14)

Question 1

What is the system of rock recycling called?

Answer 1

Rock Cycle

Question 2

How does an igneous rock become a sedimentary rock?

Answer 2

The igneous rock can be exposed to weathering to produce particles that are eroded, transported, and deposited as sediment. When lithified, it becomes sedimentary rock

Question 3

How does a sedimentary rock become an igneous rock?

Answer 3

sedimentary rock melted to produce magma, then cooled to produce igneous rock.

Question 4

Sedimentary rock to Metamorphic rock?

Answer 4

sedimentary rock put under high temperatures and pressures

Question 5

Metamorphic to Sedimentary Rock?

Answer 5

metamorphic rock can be weathered to produce particles that are eroded, transported, and deposited as sediment

Question 6

Metamorphic to Igneous?

Answer 6

metamorphic rock can be melted to produce magma that cools to become an igneous rock

Question 7

Igneous Rock to Metamorphic rock?

Answer 7

igneous rock put under high heat and pressure to become metamorphic rock

Question 8

What is one of the reasons why movement takes place on the Earth’s surface?

Answer 8

because heat flow within the Earth is not uniform

Question 9

how does hot material and cold material flow throughout the mantle?

Answer 9

hot material flows upwards, cold material flows downwards

Question 10

What produces the huge convection currents in the mesosphere

Answer 10

the cells of rising and sinking mantle

Question 11

what material in the mantle, flows most readily and why?

Answer 11

the Asthenosphere, because it is solid, but in a near-liquid state

Question 12

what is the boundary between the mantle and crustal part of the lithosphere called?

Answer 12

the Mohorovicic Discontinuity or “Moho” for short

Question 13

the lithosphere (the brittle outer shell of the Earth, is not a continuous sheet but rather ____

Answer 13

broken into tectonic plates

Question 14

Explain how the plates of lithosphere actually move

Answer 14

through something called Convection.

Convection currents in the asthensophere drag the pieces of lithospheric plates along on the surface called “Mantle drag”

Question 15

What happens to the places where the plates were moved apart ?

Answer 15

the asthenosphere fills the cracks and spots where the plates moved apart while the far edges of the plates of lithospheric plates are dragged down by downgoing currents

Question 16

Where do ridges form?

Answer 16

where the lithospheric plates are being formed as the new lithospheric plates are least dense

Question 17

What happens when lithospheric plate cools?

Answer 17

it increases greatly in density and sinks and drags the rest of plate along with it

Question 18

“slab pull”

Answer 18

the movement resulting from the pulling of a plate down a trench by the dense edge of a plate

Question 19

what does slab pull cause?

Answer 19

causes the old, outer edge of a plate to sink

Question 20

At the present time, what is thought to create the majority of plate movement?

Answer 20

a combination of slab-pull and convection

Question 21

what are the 2 Main types of boundaries?

Answer 21

A divergent boundary - the boundary between 2 plates that are moving APART

A convergent boudnary - the boundary between 2 plates that are moving toward one another (Converging)

Question 22

what are divergent boundaries represented by in the ocean floor?

Answer 22

mid-ocean ridges (e.g., East Pacific Rise, Mid-Atlantic Ridge)

Question 23

what are convergent boundaries represented by?

Answer 23

Trenches

Question 24

The 2 types of Crust

Answer 24

Oceanic Crust (mafic crust underlying the oceans) Continental Crust (felsic crust that underlies the continents)

Question 25

what are the 2 main differing characteristics of an Oceanic and Continental crust and how do they differ?

Answer 25

Density and thickness

continental crust is lighter and thicker than oceanic crust

Question 26

What is the effect of density on the way oceanic plates and continental plates

Answer 26

oceanic lithosphere floats low on asthenosphere (forming ocean basins)

Continental lithosphere floats high on asthensphere (forming continents)

Question 27

what is the dependence of the level of floatation on thickness and relative density of the materials called

Answer 27

Isostasy meaning “equal standstill”

Question 28

why iscontinental lithosphere taller than the oceanic lithosphere?

Answer 28

THICK continental lithosphere, with thick roots, stands higher on the asthenosphere

Question 29

why does it matter that continental lithosphere is diff from oceanic lithosphere?

Answer 29

oceanic lithosphere is continuously created at oceanic ridges and destroyed at subduction zones (so quite young). However, slabs of continental lithosphere float like rafts as it is buoyant so this is why contients contain such old rocks

Question 30

How are ocean basins formed?

Answer 30

1. in interior of contient, heat can rise from the underlying mantle
2. upwards the lithosphere of continent
3. cracks develop in this upwarded area, forming rift valleys
4. mafic magma generated by decompression melting close to surface

4.b) Magma than cooled at depth to form gabbro of lower crust

5. Magma that cools at surface forms basalt
6. 2 of the arms continue to spread, forming oceanic lithosphere of an ocean basin, while the remaining failed arm stops spreading and is fillied with sediment

Question 31

What is the proof that we have that continents have moved around and seas can open and close?

Answer 31

evidnece from Alfred Wegener, who noticed that the contients could be fit together like a puzzle

created the concept of “continental drift”

Question 32

What was the argument for the concept of “continental drift”

Answer 32

it was that the distribution of certain fossils of land animals and plants could only be explained if all the continents were once together

Question 33

what are the 3 main types of convergent plate boundaries?

Answer 33

Oceanic-oceanic convergence

Oceanic-continental convergence - (subduction of OL)

Continent-continent collision

Question 34

What is formed through oceanic-oceanic convergence?

Answer 34

magma generated from hydration melting rises to form an ISLAND ARC

Question 35

what is formed through Oceanic-continental convergence

Answer 35

molten material from hydration melting rises to form an CONTINENTAL ARC

Question 36

the process of subduction is indicated by 3 things”

Answer 36

the existence of ocean trenches (deepest area of the ocean)

explosive volcanoes

severe earthquakes

Question 37

what is a trench?

Answer 37

a trench is the surface expression of a subduction zone where oceanic lithosphere begins its descent

Question 38

what is an additional consequence of convergence in plate tectonics

Answer 38

the development of clastic wedges which are derived from wearing-down of mountains that were created through the uplifting during the convergence of the plates

Question 39

what are zones where lithospheric plates move alongside one another called?

Answer 39

transform plate boundaries – basically “offsets” that form within moving plates