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expose ocean zones

publicité
THEME
CHARACTERIZATION OF
OCEANIC ZONES
Presented by
ASHU NGONO STEPHANIE VANESSA
Under the supervision of
Dr. SADEM KENFACK
Content
▪
Introduction
▪
What are ocean zones?
▪
Different types of ocean zones and their caracteristics
▪
Conclusion
Introduction
▪
The oceans are vast. They cover approximately two-thirds of the surface area of
our planet and extend much deeper than the height of the tallest mountain.
▪
The parts of the ocean are as varied and diverse as those found on land.
▪
Each ocean is subdivided into zones based on the water’s depth.
▪
What are these ocean zones and how are they caracterized?
▪
This presentation has as main objective to bring answers to this question.
What Are Ocean Zones?
▪
To make understanding the oceans more
manageable, scientists have organized oceans into
various zones.
▪
These divisions help us better understand the
characteristics of these vast bodies of water.
Different Types of Ocean Zones
▪
➢
There are four types of ocean zones:
Shoreline
➢ Continental shelf
➢ Continental slope
➢ Abyss
Source: https://study.com/academy/lesson/continental-slope-definition-facts.html visited on the
25/09/17 at 09:00 a.m
Shoreline
▪
The shoreline is the line along the edge of the ocean where land meets the
water.
▪
It is a place that is always changing due to forces acting upon it from waves,
currents and winds
▪
Shores are influenced by the topography of the surrounding landscape, as well
as by water induced erosion, such as waves. The geological composition of
rock and soil dictates the type of shore which is created

Following their caracteristics we have shoreline or shores on :
▪ Beaches
▪
Salty swamps
▪
Concrete platform where canoes land
▪
Port
A picture of the Seme Hotel Beach, Limbe, Cameroon
Source: https://www.google.com/imgres-Hotel_Seme_Beach-Limbe_Southwest_Region. =plagelimbecameroun
visited on the 25/08/19 at 10:00 a.m
A picture of a part of Bollore ports
Source:https://www.bollore-ports.com/en/who-are-we/bollore-ports-overview.html
Boat on the shoreline of the Santa Cruz port, Flores Ile , Açores Portugal Archipel
https://fr.123rf.com/photo_24946159_bateaux-sur-le-rivage-dans-le-port-de-santacruz-l-%C3%AEle-de-flores-archipel-des-a%C3%A7ores-portugal.html
Salty swamp of Ré island
Source: https://fracademic.com/pictures/frwiki/77/MaraisSalant.JP
Continental shelf
▪
The extended landmass of a continent that lies below the ocean at a shallow depth of. A
continental shelf is usually less than 500 feet below the ocean’s surface.
▪
A continental shelf has three main characteristics:

A portion of the continent that extends beyond the coastline

Lies below the ocean’s surface

Shallow depth
Certain areas of a continental coast have no shelf. These usually occur where there is a meeting
of tectonic plates at the coastline. The coast of Chile is one example of this.
How large is a Continental Shelf?
 The
average width of a continental shelf
beyond the coastline is 50 miles. The largest
continental shelf lies off the Siberian coast in
the Arctic Ocean, extending for 930 miles
into the ocean.

The actual widths of various continental shelves vary greatly. For example, parts of North
America’s continental shelf are just over half a mile long, while the shelf off of Siberia runs
approximately 40 miles underwater before hitting its shelf break. This discrepancy in size
requires that there be two different definitions for a continental shelf.

There is both a legal and geographical definition for a continental shelf. The legal definition,
which is used by the United Nations, defines the term as submerged land that extends no
further than 200 nautical miles from a continent’s coastline. Geographically speaking,
however, a continental shelf is simply the parts of continents that extend underwater to the
shelf break.
How is a Continental Shelf Formed?

Part of a continent may drop in elevation, becoming a portion of
continental shelf that borders the dry mainland. The sea level can
also rise, submerging a portion of the continent.

Part of a shelf can also rise above the water and become part of the
continent, or the sea level may drop and expose a part of the shelf.

According to scientists, over the course of 18,000 years during the
peak Ice Age, when much of water on the earth was frozen, sea
levels dipped and exposed the continental shelves.
Pictures of continental shelves
https://www.google.com/search?q=map+showin
g+continental+shelf&hl

One of the famous
continental shelves is The
North Sea that borders the
northern European and
Scandinavian countries is a
shallow sea that lies above
the continental shelf of
Europe with an average
depth of 300 feet.
Continental slope
▪
The comparatively steep slope from a continental shelf to
the ocean floor.
▪
The world’s combined continental slope has a total length
of approximately 300,000 km (200,000 miles).
Features of Continental Slopes

The angle of continental slopes are not the same everywhere.

The gradient of the slope is lowest off stable coasts without major rivers and
highest off coasts with young mountain ranges and narrow continental
shelves.

Worldwide, the angle of the continental slopes averages about four degrees,
but there are factors that affect the steepness.

When the land that borders the ocean shore has newer mountain ranges and a
narrow continental shelf, the angle tends to be steepest.

Most of the continental slopes in the Pacific are steeper than those in the
Atlantic, but the flattest continental slopes are in the Indian Ocean.
ABYSS

The deep ocean is the abyss or the abyssal zone with a depth varying between 3000 and
6000m.

The water in this region is very cold (around 3° C), highly pressured, high in oxygen
content, but low in nutritional content.

Abyssal waters originate at the air-sea interface in polar regions, principally the Antarctic.

There, the cold climate produces sea ice and residual cold brine. Because of its high
density, the brine sinks and slowly flows along the bottom toward the Equator. Abyssal
salinities range narrowly between 34.6 and 35.0 parts per thousand, and temperatures are
mostly between 0° and 4° C
Conclusion
▪
From the ever changing pools of the sea shore to the cold, dark void
of the deep ocean the Earth’s marine are both beautiful and
mysterious.
Thank you for your kind attention
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