Atlantic Margin History

Question 1

initial rifting

Answer 1

triassic (200 mya), no oceanic crust yet, embryonic stage of the wilson cycle

Question 2

jurassic margin

Answer 2

150 mya, spreading starting, juvenile stage of the wilson cycle

Question 3

present day

Answer 3

passive atlantic margin, reef died about 100 mya

Question 4

Pleistocene

Answer 4

began 2.5 mya, ended 11,000 ya, repeated advance and retreat of glaciers in northern hemisphere, sea level rise with fluctuations

Question 5

interglacials

Answer 5

‘warm periods’, warmest spell was in the pleistocene about 125,000 ya, seas were higher than today

Question 6

escarpments

Answer 6

a long, steep slope, separating areas of land at different heights, represent ancient shorelines

Question 7

last glacial maximum

Answer 7

18,000 ya, glaciers covered more than 1/3 of Earth’s land mass, oceans were about 120 meters lower than today

Question 8

what was present during low stands of the pleistocene?

Answer 8

ice caps and glaciers, the shelf showed river channels, erosion rates increased, coral reefs exposed, winnowing occurred showing relict sediment