Plate Tectonics

Question 1

Continental drift theory

Answer 1

All present day continents were once part of a single supercontinent (Pangaea)
Proposed in 1918 by Wegener

Question 2

Wegener’s evidence

Answer 2

• continents fit together
• fossil evidence (same non-aquatic animals found all over world (matching it shows all the continents fit together))
• similarities in rock sequence (same thickness and order)
• pole wandering (WRONG) (pole wanders, continents move)

Question 3

Plate tectonic theory

Answer 3

• rigid lithosphere floats on semi-rigid asthenosphere
• lithosphere is broken into plates (about 30)
• constant movement created by earth’s features

Question 4

Layers of earth (top to bottom)

Answer 4

Crust
Mantle (lithosphere, asthenosphere)
Outer core
Inner core

Question 5

Lithosphere

Answer 5

• rigid
• crust + uppermost mantle
• plate of tectonic plates

Question 6

Asthenosphere

Answer 6

• part of solid mantle that flows (plastic flow (!))
• part of convection currents that move lithospheric plates
• semi rigid
• much denser than lithosphere and crust

Question 7

What drives plate movement

Answer 7

Convection currents

Question 8

What is subduction

Answer 8

One plate beneath another plate

Question 9

Eastern Caribbean (St. Lucia, st. Vincent, etc)

Answer 9

• Caribbean + North American plates

- oceanic-oceanic

Question 10

Andes

Answer 10

• nazca + South American plates

- oceanic-continental

Question 11

Ring of fire

Answer 11

Pacific + lots

-oceanic-continental

Question 12

Cascades volcanoes

Answer 12

• NA + Juan de fuca plate

- oceanic-continental

Question 13

Himalayas

Answer 13

• india + Eurasia plates

- continental-continental

Question 14

Appalachians

Answer 14

Ancient NA + Eurasian
-continental-continental
2 plates are now fused together

Question 15

Results of oceanic-oceanic

Answer 15

Volcanoes

Small islands of big enough

Question 16

Results of oceanic-continental

Answer 16

Mountains

Volcanoes

Question 17

Results of continental-continental

Answer 17

NO SUBDUCTION

Mountains (both go up)

Question 18

Sinai (Red Sea)

Answer 18

Eurasian + African plates

Divergent

Question 19

Mid-Atlantic ridge

Answer 19

African + South American
Nor American + Eurasian
Divergent

Question 20

African rift zone

Answer 20

African + Indian + Arabian plates

Divergent

Question 21

Sam Andreas fault

Answer 21

Pacific + North American plate

Transform

Question 22

Clarion fracture zone

Answer 22

Pacific + North American plates

Transform boundary

Question 23

Alpine fault

Answer 23

Australian + pacific

Transform boundary

Question 24

Hawaii

Answer 24

Hot spot

Pacific plate

Question 25

Iceland

Answer 25

Between Eurasian and North American plates | Hot spot

Question 26

Yellowstone

Answer 26

North American plate | Hotspot

Question 27

Results of divergent boundaries

Answer 27

Plates pull away from each other (new crust)

Question 28

Results of transform boundaries

Answer 28

-crust is neither produced nor destroyed as plates slide horizontally past each other

Question 29

Results of hot spots

Answer 29

Constant hot pocket | Chain of volcanoes

Question 30

Continental crust

Answer 30

Granite has big crystals (cool SLOW in dirt) - Granitic rocks - relatively lightweight minerals (Quartz + feldspar)

Question 31

Ocean crust

Answer 31

Salt has small crystals (cool FAST in water) - basaltic rocks - denser + heavier

Question 32

Continent + ocean

Answer 32

Continental on top (lighter)

Question 33

Continental + continental

Answer 33

Both go up

Question 34

Oceanic + oceanic

Answer 34

One goes under because they're so heavy

Question 35

Plate boundaries

Answer 35

- points where different plates meet - most beneath oceans - earthquakes and volcanoes concentrated there

Question 36

Rift

Answer 36

- place where earth's crust and lithosphere are being pulled apart - NO new crust/lithosphere formed

Question 37

French

Answer 37

Hemispheric long but narrow topographic depressions of sea floor

Question 38

Ridge

Answer 38

New oceanic crust + lithosphere is created by seafloor spreading NEW crust/lithosphere formed

Question 39

Fault

Answer 39

Layers (cracks) in earth's crust that are the result of different motion within the crust

Question 40

How can we tell where the plates meet? (Land)

Answer 40

Volcanoes Earthquakes Mountains

Question 41

How can we tell where the plates meet? (Oceans)

Answer 41

GEOSAY satellites map ocean floor

Question 42

Craton

Answer 42

Ancient rock at core of continent

Question 43

Terranes

Answer 43

Large block of lithospheric plate that has been moved and attached to the edge of a continent Contributes to the growth of continents cache creek Terrane in BC Canada

Question 44

How to identify a terrane

Answer 44

- surrounded by major faults - rocks and fossils don't match those of continent - magnetic record is different from continent

Question 45

River sediments and continent growth

Answer 45

Sediments (eroded rock and soils) build up on edges of containers Mississippi River delta

Question 46

Igneous rock and container growth

Answer 46

Plutons formed from magma that rises beneath the surface and cools Volcanoes at subduction boundaries eject lava, ash, rock materials (added to edge) Chains of volcanic islands from subduction zones may be added

Question 47

Modern evidence for plate tectonics theory

Answer 47

Arthur Holmes 1. seafloor spreading 2. Magma hardens + ferromagnetism - looking at rocks on sea floor shows pole flipping