The _____ is the extended margin of each continent occupied by relatively shallow seas and gulfs.

The correct answer is continental shelf.

Important Points

• The continental shelf is the extended margin of each continent occupied by relatively shallow seas and gulfs.
• The Continental Shelf of all oceans together covers 7.5% of the total area of the oceans.
• The gradient of continental is 1° or even less.
• The continental shelves are covered with variable thicknesses of sediments brought down by rivers, glaciers, etc.
• Massive sedimentary deposits received over a long time by the continental shelves become the source of fossil fuels [Petroleum].
• Seaward extension of the continent from the shoreline to the continental edge approx. 200 m deep.
• In some places, where the coasts are extremely mountainous, such as in the Rocky Mountains, the continental shelf may be entirely absent.

 Additional Information

• Continental slope:
  • When seaward slope immediately becomes steep & gradient to about 1 in 20 with average depth 200 – 3000m.
  • Most of the canyons & trenches are observed in this region.
  • The continental slope connects the continental shelf and the ocean basins. ​
• ​Abyssal Plains:
  • The average depth is 3000 – 6000 m.
  • These plains are covered with fine-grained sediments like clay and silt.
• ​Oceanic Trench:
  •   They are some 3-5 km deeper than the surrounding ocean floor.
  • The trenches lie along the fringes of the deep-sea plain at the bases of continental slopes and along island arcs.
  • The trenches run parallel to the bordering fold mountains or the island chains.
• Deepest trench in the world → Marina trench (11 km) of Guam Islands (Pacific Ocean)