The continental shelf is a shallow submerged region of continent that extends from the shoreline to the shelf break. It includes three zones - inner, mid, and outer continental shelf. Continental shelves were formed during glacial periods when sea levels dropped and exposed land that is now submerged. The average shelf is 80 km wide and 150 m deep, ending at the shelf break which marks the start of the steep continental slope. Continental shelves support rich ecosystems due to nutrients from land and ocean and most of the world's fish populations live along continental margins. They also provide resources like oil and minerals and are important for fisheries.

1. Continental Shelf
Assigned by:
Mam Umm-e-Ammara
By :
Fatima Islam
Yasir Mehmood
M. Usama sami

2. Definition:
• A continental shelf is a portion of continent that is
submerged under an area of relatively shallow water
known as continental shelf.
• Much of the shelves were exposed during glacial periods
and inter-glacial periods.
• Continental shelves are flat submerged edges of the
landmass.
• The continental shelves are covered by terrigenous
sediments; that is, those derived from erosion of the
continents.

4. Types of Continental Shelf:
• Inner continental shelf
• Mid continental shelf
• Outer continental shelf

5. Location:
• A continental shelf extends from the coastal line of
the continent to a drop-off point called the shelf
break. From the break, shelf descends toward the
deep ocean floor in what is called continental
slope even though they are under water,
continental shelves are the part of continent.

6. Shelf Break:
• The shelf usually ends at a point of increasing slope.
• Shelf break is located at remarkably uniform depth of
roughly 140 m (460 ft.)
Continental Slope:
• The sea floor below the break is continental slope.
• The continental slope is much steeper than shelf.
• The average angle is 3° but it can be as low as 1° as high
as 10 °.

7. How it is formed:
• Continental shelves were formed in
between glacial periods as the oceans
flowed over the continents forming shallow
areas along the coasts.
• About 18 thousand years ago during the
height of Pleistocene ice ages, much of
what is now a continental shelf was actually
above water.

9. Depth:
• The continental shelf is one volume in facts files life
in the sea. The depth of shelf also varies but is
generally limited to water shallower than 150 m
(490 feet).The slope of shelf is usually quite low on
the order of 0.5 degree; vertical relief is also
minimal, at less than 20 meters (66 ft.).
Width:
• The average width of continental shelf is about 80
km (50 miles).

10. Temperature:
• Sea surface temperature for the Northeast shelf
ecosystem reached record high of 14°C (57.2°F).
• In 2012, exceeding the previous record high in
1951.
• Average SST has typically been lower than 12.4°C
(54.3°F) over the past three decades.

11. Continental Margins:
• The continental margins is between the
continental shelf and abyssal plane comprises a
steep continental slope followed by the flatter
continental rise.
• The continental shelf and the slope are part of the
continental margins.
• Worldwide continental margins are only the small
portions of the oceans making of the mere 8% of
the surface and only 0.2% of the total volume.

12. Types of Continental Margins:
• Passive continental margins (wide & shallow
shelves made of thick sedimentary wedges)
• Active continental margins (narrow & steep
shelves)

13. Continental Rise:
• Sediments from the continent above
cascades down the slope accumulates as
a pile sediment at the base of slope called
the continental rise.
• The continental rise’s gradient is
intermediate between the slope and the
shelf.

15. IMPORTANCE
• Shelf waters are rich in nutrients which they
receive from both ocean and land. For this
reason marine environment on the
continental shelf are able to support dense
population of living things
• Continental Shelf surface contains most of
the marine Animals and Plants

16. Plant Life:
• Plant life depends upon the extent of
penetration of sunlight in the continental
shelf.
• Plants can survive in the shallower regions of
the continental shelf but it gradually
decreases with the depth due to the
deficiency of sunlight.

18. Food Chain:
• Due to the presence of producers in continental
shelf it supports the food chain.
Animal Life:
• 99% of the ocean’s fish make their homes along
the continental margins.
• Shelf water contains cnidarians, jelly fish,
molluscus, crustaceans and tunicates.

20. Economic Importance:
• Fishermen earn their livings mostly from the
near-shore regions of the ocean.
• Continental shelf provides us with metallic
and non-metallic ore.
• In US most of the petroleum is obtained from
the continental shelf.

21. Bibliography:
• Title: The continental shelf
(Life in sea series, Palm Walker) Chapter 1
Author: Palm Walker, Elaine Wood
Publisher: Infobase Publishing, 2009
• Gross, M. Grant (1972)
(Oceanography: A view of the earth)

22. THANK YOU
YASIR MEHMOOD