Fichas
ers test2
Fichas del conjunto (20)
- 1how old is ocean crust?150, 000 to 160, ooo years old
- 2who was alfred wegenerproposed pangea - theory of plate tectonics and continental drift
- 3how were oceanic magnetic strip found?s?sonar and mangetometers used to map the sea floor
- 4difference between magnetic north pole and geographic north polethe magnetic north pole is 200 km away from the geographic
- 5how often do magnetic stripes switch polarity?ever 0.4 million years (170 reversals in past 70 m/y - indicated by magnetic minerals
- 6how do we know magnetic stripes changed polarity?symmetrical patterns produced from mapping regular and reversed polarity corresponded to those found in continental volcanoes
- 7sea level during glacial times?130 meters below
- 8when was the last glacial period?20, 000 years ago
- 9when did ice age start?2.6 million years ago - beginning of pleistoscene epoch era
- 10how did the shelf break form?the up and down of sea levels from glacial and inter glacial periods (130m altitude difference)
- 11explain active and passive continental margin typespassive margins are more expansive (widest in arctic ocean) and active margins have narrower shelf areas
- 12describe the continental margin features - names, distance, depth.1. continental shelf (0-350km)
2. shelf break (350km)(0-500m)
3. continental slope (50 km) (0.5-1.5km)
4. continental rise (500km) (1.5-4.5km)
5. abyssal plain (300+km) (4.5km)
- 13Where does the deep ocean basin begins?at the continental slope (after the shelf break)
- 14Angle of continental slope?as steep as 25 degrees!
- 15what is the source of sediments on the continental slope?sediment from rivers connecting to the continental shelf
- 16what is the mode of transport of the sediments to the continental rise?turbidity currents
- 17describe turbidityevent deposits (take place as events), is a current made of a frontal area (head) and followed with a tail (laminar flow, finer grain). Underwater avalanches
- 18what causes turbidity events?an earthquake or just pile gets big enough that starts tricking down
- 19describe a turbidite graded bedlower layer - eroded ocean floor surface, 2nd layer - coarse grain from turbid head, 3rd layer - fine grain from turbid tail, 4th layer repeat as more turbid events take place
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- Fichas sobre ers test2, creado por Tanzeela Tt el 05/03/2019.
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