Oceans of Today

Lets dive down and see what lies in our oceans today!

Hold Your Breath, Here We Go!

Dip a toe in any ocean and you are linked to all the world's ocean as the earth's seawater is one continuous mass. The largest expanses are called oceans while the smaller ones (usually close to, or partly enclosed by, land) are called seas. Two-thirds of the Earth's surface is covered by seawater, which makes up to 97 percent of the planet's entire water supply. Seawater's temperature varies in different areas- it is colder at the surface in polar regions than in the tropics. Generally, seawater gets colder with depth. Seawater's salinity varies from that of the saltiest waters (such as the desert-bound Red Sea where there is a high evaporation rate and little inflow of freshwater) to one of the least salty (the Baltic Sea where there is a high inflow of freshwater from rivers). Nor is the bottom of the ocean the same everywhere. there are undersea mountains, plateaus, plains, and trenches, making the ocean floor as complex as any geological formations on land.

mens1

OCEANS OF OCEANS:

The world's five oceans, ranging from the largest to the smallest, are the Pacific, Atlantic, Indian, Southern, and Artic. The Pacific Ocean, by far the largest, covers 59 million sq miles (153 million sq km) and is about 13 times the size of the Artic Ocean. The Artic Ocean's center is permanently covered by a layer of sea ice that grows larger in winter and shrinks in summer by melting. Over half the Southern Ocean is also frozen in winter and sea ice still fringes the continent of Antarctica during the summer. The average depth of all the oceans is 12,000 ft (3,650 m) with the deepest part in the Pacific Ocean at 36,201 ft (11,034 m) in the Mariana Trench, east of the Phillippines.

SEA OR LAKE?

The water in the Dead Sea is saltier than any ocean because the water that drains into it evaporates in the hot sun, leaving behind the salts. A body is more buoyant in such salty water, making it easier to float. The Dead Sea is a lake, not a sea, because it is completely surrounded by land. True seas are always connected to the ocean by a channel.

GOD OF THE WATERS:

Neptune, the Roman god of the sea, is usually shown riding a dolphin and carrying a pronged spear (trident). it was thought he also controlled freshwater supplied, so offering were made to him at the driest time of the year.

DISAPPEARING ACT:

The gigantic plates on the Earth's crust move like a conveyer belt. As new areas of ocean floor form at spreading centers, old areas disappear into the molten heart of the planet. This diagram shows one oceanic plate being forced under another (subduction) in the Mariana Trench, creating an island arc.

THE OCEAN FLOOR:

This model shows the features on the bottom of the Atlantic Ocean off the northeast coast of South America from guyana to Venezuela. Off this coast is the continental shelf, a region of relatively shallow water about 660 ft (200 m) deep. Here the continental shelf is about 125 miles (200 km) wide, but off the coast of northern Asia is as much as 1,000 miles (1,600 km) wide. At the outer edge of the continental shelf, the ocean floor drops away steeply to form the continental slope. Sediments eroded from the land and carried by rivers, such as the Orinoco, accumulate at the bottom of this continental slope. The ocean floor then opens out in virtually flat areas (abyssal plains), which are covered with a deep ;ayer of soft sediments. The Puerto Rican Trench formed where one of the Earth's plates (the North American Plate) is sliding past another (the Caribbean Plate). An arc of volcanic islands has also been created where in North American Plate is forced under the Caribbean Plate. The fracture zones are offsets of the Mid-Atlantic Ridge.



Oceans of the past

The Earth, with its vast expanses of ocean, has not always looked the way it does today. Over millions of years the land masses have drifted across the face of the planet as new oceans opened up and old oceans have disappeared. Today's oceans only started to take shape in the last 200 million years of the Earth's 4.6-billion-year existence. But water in the form of vapor was present in the atmosphere of the early Earth. As the Earth cooled, water vapor condensed, making storm clouds from which rain fell and eventually filled the oceans. Water also came from space in the form of icy comets. As the oceans themselves changed, so too did life within the oceans. Simple organisms first appeared in the oceans 3.5 million years ago and were followed by more and more complex life forms. Some forms of life became extinct, but others still survive in the ocean today, more or less unchanged.