OceanographyLesson 5 of 5 in the course Seafloor and ocean basins

Abyssal Plains: Formation, Sediments, Ecology, and Human Impacts

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

An abyssal plain is one of the largest and least explored features of the ocean floor. This lesson introduces its location, depth, physical character, and place within the ocean’s depth zones.

An abyssal plain is a broad, nearly level region of the deep ocean floor, usually at depths of 3,000 to 6,000 metres. It generally lies between the foot of a continental rise and a mid-ocean ridge. These plains cover more than 50% of Earth’s surface and are among the flattest, smoothest regions on the planet.

All flashcards

Abyssal plain
A broad, nearly level deep-ocean floor region, usually 3,000–6,000 metres deep.
Seafloor sediment smoothing
The gradual burial of irregular oceanic crust by accumulating fine-grained sediment.
Chemosynthesis
The production of organic matter using chemical energy rather than sunlight.
Food-limited abyssal community
A deep-sea community whose structure is constrained by scarce food reaching the seafloor.
Subduction
The sinking of older, denser oceanic lithosphere into the mantle at a convergent boundary.

Quiz questions

  1. What process causes some rising mantle beneath a mid-ocean ridge to melt as pressure decreases?Answer: Decompression melting
  2. What kind of sediment-rich flow can carry material downslope from continental margins into deep water?Answer: A turbidity current
  3. Which group of metals can occur in polymetallic nodules on abyssal plains?Answer: Manganese, iron, nickel, cobalt, and copper
  4. Which technology maps seafloor depth across wide areas with high precision?Answer: Multibeam sonar
  5. Why can deep-sea fish populations be vulnerable to fishing pressure?Answer: Many species are long-lived and slow-growing.

Based on the Wikipedia article Abyssal plain, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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