plate tectonics

Question 1

formation

Mt. Rundle

practical example

Answer 1

a large force against gravity would have been requried to push material deposited below sea level kilometers above

primarily composed of limestone rock which formed in shallow ocean basin

Question 2

contracting Earth theorly

Answer 2

theory that Earth contracted / shrank over geologic time due to gradual cooling
* scientifically fragile

contortions explained mountain formation

Question 3

flaws of contracting Earth theory

Answer 3

• no evidence to suggest Earth had cooled drastically
• distribution of mountain ranges is not quite random
• amount of contraction required to form large mountains unrealistic

Question 4

contributers

“Jigsaw” Fit Evidence

Answer 4

• Frances Bacon (1620)
• Antonio Sinder-Pellegrini (1858)
• Alfred Wegener (1880-1930)

Question 5

“Jigsaw” Fit Evidence

Alfred Wegener’s Continental Drift Hypothesis

Answer 5

continental margins fit together like puzzle pieces, the best match is when continental shelves are used rather than continental edges

Question 6

glacial deposits evidence

Alfred Wegener’s Continental Drift Hypothesis

Answer 6

evidence of Permain glaciers found on four continents
* some near the equator where glaciers do not typically occur
* distribution of deposits converge near south pole when continents are regrouped
* distribution of glacial striations indicate ice flow direction

Question 7

paleoclimate evidence

Alfred Wegener’s Continental Drift Hypothesis

Answer 7

rocks preserve climate belts
* tropical coals formed in anciet swamps/forests
* tropical reefs
* subtropical deserts
* subtropical evaporites

Question 8

paleontological evidence

Alfred Wegener’s Continental Drift Hypothesis

Answer 8

identical fossils found on widely seperated landmasses

Question 9

matching geologic units

Alfred Wegener’s Continental Drift Hypothesis

Answer 9

distinctive rock assemblages match across the Atlantic
* geologic structures
* rock types
* rock ages

matching mountain belts
* i.e. caledonian mountains

Question 10

Opposing theories

Alfred Wegener’s Continental Drift Hypothesis

Answer 10

suggested alternative interpretations of his findings
* isthmianlinks (trans-oceanic land bridges)
* rafting
* island stepping stones

improbable hypothesis

Question 11

Wegener’s hypothesis flaw

Answer 11

lack of a reasonable mechanism for movement of the continents

suggested continents ‘plowed’ through the oceans