1 hrly gs ch 04 oceans

Oceans, Seas, Lakes and Others

Ocean

• Definition– An ocean is a body of salt water with no

boundaries and limitless volume

• It is the largest water body

• There are only five oceans in the world in the order of size (largest to smallest)– The Pacific Ocean– The Atlantic Ocean – The Indian Ocean– The Southern Ocean – The Arctic Ocean

• The Southern Ocean was approved in 2000 by the International Hydrographic Organization. It is now the fourth largest ocean

• Largest Ocean– The Pacific Ocean is the

largest ocean in the world. – It covers almost one third of

the Earth's surface

• Smallest Ocean– The smallest ocean is the

Arctic Ocean, which is about 10 times smaller than the Pacific Ocean

• Ocean beds are very deep, and support only very basic life forms like bacteria and shrimp– Because no light reaches there

and the pressure are such that marine life cannot survive

• An idea of the ocean depth the Pacific Ocean has an average depth of 3790 meters or 12,430 feet

Sea• Definition

– A sea is part of an ocean that is partially surrounded by land

• If it is totally surrounded by land, then it's called an inland sea– Example

• Caspian Sea• Aral Sea

• Seas being close to land are generally much shallower than ocean– Therefore, it is possible for plant

and animal life to thrive on a sea bed because it is generally lit up by light

• The average depth of the Mediterranean Sea on the other hand is 4690 feet

• There are numerous seas. Following are few seas (by size):– South China Sea Asia– Caribbean Sea North America– Mediterranean Sea Asia, Europe,

Africa– Bering Sea Asia and North America– Arabian Sea Asia– Sea of Okhotsk Asia– Sea of Japan (East Sea) Asia– East China Sea Asia– Andaman Sea Asia– Black Sea Asia and Europe– Red Sea Africa and Asia

Gulf

• Definition– A deep inlet of the sea almost surrounded

by land, with a narrow mouth– A body of water surrounded by land from

three sides

• Following are of the gulfs– Gulf of Mexico – Persian Gulf– Gulf of Oman– Gulf of Alaska– Gulf of Saint Lawrence

Bay• Definition

– An area of water mostly surrounded by land

• A large bay may be called a gulf or a sea

• Bays generally have calmer waters than the surrounding sea– Because the surrounding land blocks some

waves and often reduces winds

• Following are some bays:– Hudson Bay – Bay of Bengal– Bay of Biscay

• Bays and gulfs were significant in the history of human settlement because – They can provide a safe place

for fishing as they have varied marine geology

– Later, they were important in the development of sea trade as the safe anchorage they encouraged their selection as ports

Lake• Definition

– A body of relatively still fresh or salt water of considerable size that is surrounded by land from all sides

• Lakes are inland and not part of the ocean

• They are larger and deeper than ponds

• Very large lakes are called seas– Caspian sea– Aral Sea

• There are some natural lakes and some artificial (man-made) lakes

• Natural lakes– Caspian Sea (Khazar Lake), Asia– Lake Superior, North America– Lake Victoria, Africa– Huron Lake, North America– Lake Michigan, North America– Aral Sea, Asia– Tanganyika, Africa

• Artificial Lakes– It is also called a reservoir – A reservoir is an artificial lake

used to store water.

– Reservoirs are often created by building a reinforced dam or a barrage

Dam

Barrage

Waterfall

Definition– A cascade of water falling from a height,

formed when a river or stream flows over a precipice or steep incline

– A waterfall is a place where flowing water rapidly drops in elevation as it flows over a steep region or a cliff

• Tallest Waterfalls– Angel Falls, Venezeula– Tugela Falls, South Africa– Tres Hermanas, Peru– Olo'upena Falls, USA– Yumbilla, Catarata, Peru

Angel Falls - Venezeula

Tugela Falls - South Africa

Tres Hermanas - Peru

Olo'upena Falls - USA

Yumbilla, Catarata - Peru

Niagara Falls, North America