Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
10 Cards in this Set
- Front
- Back
|
What 3 regions make up the passive continental margin?
|
- continental shelf
- continental slope - continental rise |
|
|
What is significant about the continental shelf?
|
- contains important mineral deposits including reservoirs of petroleum and natural gas.
|
|
|
What are turbidity currents?
|
- downslope movements of dense, sediment-laden water.
- they are created when sand and mud on the shelf and slope are dislodged, perhaps by an earthquake and are thrown into suspension. |
|
|
What are submarine canyons?
|
- deep, steep sided valleys that cut into continental slope and may extend across the entire continental rise
|
|
|
What are some features of the deep-ocean basin?
|
1) deep ocean trenches
2) abyssal plains 3) seamounts (as volcanoes emerge from sea level, they are eroded by running water and wave action, and eventuall sink, creating tablemounts. |
|
|
How do rift valleys get its rugged topography?
|
- as newly created hot oceanic crust rises and occupies the spreading seafloor, it takes up more volume than the adjacent cooler rocks. As it travels away, it cools and contracts. Eventually it is covered by sediment and belongs to the deep-ocean basin.
|
|
|
What are the 3 levels of oceanic crust?
|
1) Upper layer- pillow lavas that are composed mainly of basalt
2) Middle layer is composed of sheeted dykes which come from the underlying magma chamber. 3) lowest layer is composed of gabbro |
|
|
What is an atoll
|
- coral islands that were once volcanic islands.
- coral reefs are formed on the flanks of volcanic islands and as the island slowly sinks due to seafloor spreading, only the coral reef is left above sea level, creating an atoll. |
|
|
What is continental drift?
|
- continents that were once a former supercontinent pangea have now seperated.
- evidence such as fit of the continents, fossils, similar mountain belts are evidence of this hypothesis. |
|
|
What is the seafloor spreading hypothesis?
|
- created by Harry Hess in the early 1960s.
- proposed ocean ridges are located above zones of upwelling in the mantle. - deep sea drilling provided evidence of this theory, the sediment got older as you moved away from the ridge crest. - sediment was no existent on the ridge crest. |
