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The ocean floor and its features
Ocean floor (sea-bed) refers to a landscape found at the bottom of the ocean. The ocean floor is made up of various features. The major features of the ocean floor include the continental shelf, the continental slope, oceanic ridges, deep sea plain, ocean deep (trench), ocean plain, oceanic island, and submarine plateaus.
Continental shelf
A continental shelf is a gently sloping margin of a continent that is occupied by shallow waters that extend from the coastline to a depth of about 200 metres towards the continental slope. Some continental shelves provide excellent fishing grounds in the world because they are shallow, and they
allow the sun’s rays to reach the shelf floor.
Hence, they provide good conditions for the growth of plankton, which fish feed on.
Continental slope
A continental slope is found at the point where the continental shelf forms a steep slope towards the ocean basin.
Mid-ocean ridge
A mid-ocean ridge is a raised part of the ocean floor. Some of these ridges appear above the surface of the ocean as oceanic islands such as Azores in Portugal and Bouvet in Norway. Examples of the mid- oceanic ridges are the Mid-Atlantic Ridge in the Atlantic Ocean and the Mid-Indian
Deep sea-plain
Deep sea-plains are extensive undulating areas of the ocean floor. It is also known as abyssal plains. Large parts of these plains are covered by thin layers of sediments of both organic and inorganic materials brought in by rivers and some from broken rocks of the ocean floor and cliffs.
Abyssal hill
Abyssal hill are small sharp hills rising from abyssal plain surface.
Ocean deep
An ocean deep (trench) is a long narrow steep sided depression plunging from the deep sea-plain to the depths of 10000 metres or more. The deepest known ocean trench in the world is Mariana Trench, which is approximately 11000 metres deep. It is located 11035 metres off the Island of Guam in the Pacific Ocean.
Island
An island is a piece of land surrounded by water. Islands may occur in oceans, seas, lakes or rivers. A group of islands is called an archipelago. Examples of an archipelago include Islands of Zanzibar and the Comoros. There are three types of islands: continental islands, oceanic islands, and coral islands.
(a) Continental islands
A continental island is a large unbroken landmass similar to a continental landmass rising from a continental shelf. Examples of continental islands include Mafia, Pemba, Unguja, Philippines, Indonesian, Greenland, and Sri Lanka.
(b) Oceanic islands
Oceanic Islands rise directly from the ocean floor. Some of the oceanic islands are the tops of oceanic ridges, plateaus, and ocean floor volcanoes. Examples of oceanic islands are Hawaii, Cape Verde, Iceland, Canary, and Seychelles.
(c) Coral islands
A coral island is an island, which is built up from limestone rocks made of skeletons of very small marine organisms.
MZUMBE SECONDARY SCHOOL FORM SIX GAUGING EXAMINATION 2024
HISTORY
ENGLISH LANGUAGE
GEOGRAPHY
PHYSICS
CHEMISTRY
BIOLOGY
ADVANCED MATHEMATICS
BAM