Tectonic plates

Question 1

When was continental drift proposed? by who

Answer 1

1915
Wegener

Question 2

What was the name of the supercontinent? When did it begin to drift into the smaller fragments that they are today?

Answer 2

Pangea
Mesozoic era

Question 3

Continental Jigsaw line of evidence

his “fit” of the continents wasn’t a great approximation

Answer 3

similarity btw the coastlines on opp. sides of Atlantic ocean

bc including the continental shelf would be better

Question 4

Fossil line of evidence
1fossil (reptile)

reptiile name
describe it
where was it found
why its evidence

Answer 4

Mesosaurus: small, aquatic freshwater reptile
- found in south america and africa (was together in pangea)
- can’t swim vast ocean (salinity) and it’s remains would’ve been scattered

Question 5

Fossil line of evidence
1 fossil (plant)

name
description
where it was found
why it supports pangea

Answer 5

Glossopteris: seed ferns with seeds to heavy to be carried by wind
- Africa, Australia, India, Antarctica, and South America
- only grow in cold climates
in Pangea, these places would be by the south pole

Question 6

Rock Types and Geological features line of evidence

Answer 6

deformed igneous rocks in Brazil match similar tocks of same age in Africa

Appalachians goes northeastward and disappear in newfoundland but similar ones of simmilar age are in the british isles and scandinavia, put together in pangea forms a mt chain

Question 7

What rocks are older, continental or oceanic?

Answer 7

continental

Question 8

where can glaciers be found today

Answer 8

anywhere except along the equator

Question 9

Lines of evidence: ancient climates
era and where was the glacial period? what was one proposal against this? how was it rejected?

Answer 9

paleozoic era in Africa, South America, Australia, and India (glacial deposits found there-near the equator)
- global cooling
- tropical swap deposits in US and Eastern Europe (northern hemisphere) in the form of coal, fossils were produced by ferns in warm climates
- Pangea: southern continents were near south pole=glacier deposits
northern continents were near equator=tropical swamps

Question 10

Objections to continental drift

mechanism
breaking through crust

Answer 10

• inability to identify a credible mechanism for continental drift, said gravitational forces of moon and sun moved continents
• said large continents broke through thinner oceanic crust, but no evidence of oceanic crust weak enough to let continents pass without being deformed

Question 11

Where are most divergent plate boundaries located?

Answer 11

Along crests of oceanic ridges

Question 12

What are spreading centers?

where is it found?
plate boundary?
process

Answer 12

Mid ocean ridges at divergent plate boundaries that produce fractures in oceanic crust and rising magma/volcanic eruptions fills voids and cools to create new sea floor

Question 13

Oceanic ridges

Answer 13

Elevated areas of the sea floor with high heat flow and volcanism

Question 14

Who proposed sea floor spreading? How did his theory contract with Wegener?

Answer 14

Harry Hess
Moving continents plowed through moving oceanic floors

Question 15

Why are ridges high?

Answer 15

New oceanic lithosphere use hot and less dense than those farther away from upwelling zone

Question 16

Where does ocean depth increase

Answer 16

Farther from ridge crest

Question 17

Where is thicker vs thinner sediment and why

Answer 17

• Older lithosphere away from ridge crest has more time to cool and contract and is buried by sediment bc its away from upwelling
• asthenosphere cools and becomes rigid and converts to lithosphere

New lithosphere can’t cool bc it’s so hot- no sediment at ridges

Question 18

Where should the youngest and oldest ocean floor be?

Answer 18

Near mid ocean ridge
Far from mid ocean ridge

Question 19

What is rifting

Answer 19

1. Continental plate motions produce tensional forces that stretch and thin the lithosphere
2. Mantle upwelling and lithosphere upwarping
3. faults created, magma potentially erupts as volcanoes
4. Stretching of brittle crust causes large blocks sink creating a continental rift
5. Sea floor spreading generates a long narrow sea, oceanic crust being created btw c.c and eventually a deep ocean basin with a mid ocean ridge

Question 20

Rift Valley

Answer 20

Canyon like structure along the crest of some ridge systems

Question 21

East African rift

explain rifting
how do we know its happening
ex of in the past

Answer 21

Tensional forces have thinned lithosphere and sparked upwelling which is demonstrated by large volcanic mountains and Rift Valley is lengthen and deepen just like how the Red Sea did