Unit 6: Geology - Earth's Surface

Question 1

How can the continents fitting together be used to support Pangaea?

Answer 1

Landmasses fit together = suggests may fit together long ago

Question 2

How do fossils be used to support Pangaea’s existance?

Answer 2

• Lystrosaurus fossils found separate landmasses but animal couldn’t swim well
• Wouldn’t make sense fossils found continents separated miles ocean –> Pangaea

Question 3

How do rocks be used to support Pangaea’s existance?

Answer 3

• Similar type + age of rocks clumped together –> how this possible?
• Pangaea

Question 4

How do glaciers be used to support Pangaea’s existance?

Answer 4

• Glacers formed South + North Pole and spread out
• Center glacier in Africa –> may have been South Pole but moved northward
• If Africa could move, why not other landmasses?

Question 5

Wegener’s continental drift hypothesis

Answer 5

Alfred Wegener thought continents together (Pangaea) long ago –> slowly drifted to current positions –> continental drift
Wegener did not know how –> others not believe him

Question 6

Mid-Ocean Ridges

Answer 6

• Mountain ranges underwater
• Shallow
• Outline plate boundaries

Question 7

Ocean Trenches

Answer 7

• Underwater troughs (long, narrow) on seafloor

Question 8

Isochron Maps

Answer 8

Map using colors depict ages

Question 9

Youngest/Oldest Crust Location

Answer 9

Crust = rock
- Youngest - mid-ocean ridges
- Oldest - ocean trenches
- Symmetrical
Youngest rock found mid-ocean ridges –> new rock/crust form at those ridges

Question 10

Seafloor Spreading

Answer 10

New crust always form along mid-ocean ridges + destroyed/re-melted at ocean trenches

Question 11

What causes Earth’s crust to spread?

Answer 11

1. Earth’s crust heated from core –> rocks rise (less dense) Earth’s surface
2. Rocks splits into 2 + rocks fall (more dense) at ocean trenches –> convection (explains why symmetrical)
3. Rocks go down –> pulls land –> landmasses form (slow proccess)
   *Continents do not plow through rock on seafloor but continents move as seafloor spreads!

Question 12

What comes up from mid-ocean ridges?

Answer 12

Magma – erupts onto surface: lava
Lava cools = new crust

Question 13

Theory of Plate Tectonics

Answer 13

Earth’s surface made rigid (stiff, not flexible) slabs of rock/plates that move according to each other

Question 14

Plate Boundary

Constructive/Divergent

Answer 14

• Move away from each other (pull apart <– –>)
• Volcanoes: yes, but not explosive
• Earthquakes: yes, weak
• New crust created created as magma rises to surface
• form new mountains (ridges) - underwater
• New rift valleys

Question 15

Plate Boundaries

Destructive/Convergent
(one continental plate, one oceanic plate)

Answer 15

• Towards each other (oceanic plate subducts under continental plate)
• Volcanoes: yes, explosive
• Earthquakes: Yes
• Mountain ranges
• Ocean trenches

Question 16

Destructive/convergent
(with two continental plates, AKA collision)

Answer 16

• Towards each other (curves upwards)
• Volcanoes: no lava (crust too thick)
• Earthquakes: yes
• Fold mountaines

Question 17

Conservative/transform

Answer 17

• Side by side, in opposite directions or same direction
• Volcanoes: no
• Earthquakes: Yes
• Fault lines (cracks in crust)