Definition of History of Ocean Exploration

The earliest human exploration of the oceans is poorly known, but

pictures of boats on early cave drawings in Norway illustrate

Viking-style ocean vessels known to be used by the Vikings centuries

later. Other rock drawings around the world show dugout

canoes, boats made of reeds, bark, and animal hides. Early migrations

of humans must have utilized boats to move from place to

place. For instance, analysis of languages and genetics shows that

the Polynesians moved south from China into southeast Asia and

Polynesia, then somehow made it, by sea, all the way to Madagascar

off the east coast of Africa. Other oceanic migrations include

the colonization of Europe by Africans about 10,000 years ago,

explorations and trade around and out of the Mediterranean by the

Phoenicians about 3,000 years ago, and the colonization of North

America by the Siberians and Vikings. Ming Dynasty ocean explorations

in the early 1400s were massive, involving tens of thousands

of sailors on 317 ships. The Chinese ships were huge, including as

many as nine masts, over 444 feet (135 m) in length and 180 feet (55

m) in width. The Chinese mounted these expeditions to promote

Chinese culture, society, and technology, but they did not contribute

significantly to understanding the oceans.

The first European to reach North America was probably Leif

Eriksson, who, in the year 1000, landed at L’Anse-aux Meadows in

the Long Range Peninsula of Newfoundland, after becoming lost on

his way from Greenland to Norway. The Vikings established a temporary

settlement in Newfoundland, and there are some speculations

of further explorations by the Vikings to places as far south as

New England and Narragansett Bay in Rhode Island. Before this,

Ptolemy (in the year 140) published maps of Europe’s coastline that

were largely inaccurate, and took many years of ocean exploration

to correct. The Greek and Islamic explorers had made great strides

in understanding the geography of the world centered on the

Mediterranean Sea and Arabian Peninsula, and the records of

these explorations eventually made it into European hands where

this knowledge was used for further explorations. The Portuguese,

most notably Prince Henry the Navigator (1392–1460), were the

most avid explorers of the Atlantic, exploring northwest Africa and

the Azores in the early 1400s. In the late 1400s, Vasco de Gama

(1460–1524) made it to southern Africa and eventually around the

Cape of Good Hope, past Madagascar, and all the way to India in

1498. These efforts initialized economically important trade routes

between Portugal and India, building the powerful Portuguese

Empire. The timing was perfect for establishment of ocean trade

routes, as the long-used overland Silk Roads had become untenable

and dangerous with the collapse of the Mongol Empire and the

Turk conquest of Constantinople (Istanbul) in 1453.

In the late 15th and early 16th centuries, many ocean exploration

expeditions were mounted, as a precursor to more widespread

use of the oceans for transportation. In 1492 Christopher Columbus

sailed for Spain to the east coast of North America, and from the late

1400s to 1521 Ferdinand Magellan sailed around the world, including a

crossing of the Pacific Ocean, followed by Sir Francis Drake of England.

Later, Henry Hudson explored North American waters, including

attempts to find a northwest passage between the Atlantic and Pacific.

During the 1700s, Captain James Cook made several voyages in the

Pacific and coastal waters of western North America, improving

maps of coastal and island regions.

The early explorations of the oceans were largely concerned

with navigation and determining the positions of trade routes,

coastlines, and islands. Later seagoing expeditions aimed at understanding

the physical, chemical, biological, and geological conditions

in the ocean were mounted. In the late 1800s the British Royal

Society sponsored the world’s most ambitious scientific exploration

of the oceans ever, the voyage of the H.M.S. Challenger. The voyage

of the Challenger in 1872–76 established for the first time many

of the basic properties of the oceans and set the standard for the

many later expeditions. Ocean exploration today is led by American

teams based at several universities and the Woods Hole Oceanographic

Institute, where the deep submersible Alvin is based, and

from where many oceanographic cruises are coordinated. The

Ocean Drilling Program (formerly the Deep-Sea Drilling Project) has

amassed huge quantities of data on the sediments and volcanic

rocks deposited on the ocean floor, as well as information about

biology, climate, chemistry, and ocean circulation. Many other

nations, including Japan, China, France, and Russia, have mounted

ocean exploration campaigns, with a trend toward international

cooperation in understanding the evolution of the ocean basins.

abundant on the seafloor, many formed at the interface

between hot volcanic fluids and cold seawater, forming potentially

economically important reserves of many minerals.

The oceans cover two-thirds of the Earth’s surface, yet we

have explored less of the ocean’s depths and mysteries than the

surfaces of several nearby planets. The oceans have hindered

migration of peoples and biota between distant continents, yet

paradoxically now serve as a principal means of transportation.

Oceans provide us with incredible mineral wealth and renewable

food and energy sources, yet they also breed devastating

hurricanes. Life may have begun on Earth in environments

around hot volcanic events on the seafloor, and we are just

beginning to explore the diverse and unique fauna that can still

be found living in deep dark waters around similar vents today.

Ocean basins have continually opened and closed on

Earth, and the continents have alternately been swept into

large single supercontinents and then broken apart by the formation

of new ocean basins. The appearance, evolution, and

extinction of different life-forms is inextricably linked to the

opening and closing of ocean basins, partly through the changing

environmental conditions associated with the changing distribution

of oceans and continents.

Early explorers were slowly able to learn about ocean currents

and routes to distant lands, and some dredging operations

discovered huge deposits of metals on the seafloor. Tremendous

leaps in our understanding of the structure of the ocean basin

seafloor were acquired during surveying for the navigation of

submarines and detection of enemy submarines during World

War II. Magnetometers towed behind ships and accurate depth

measurements provided data that led to the formulation of the

hypothesis of seafloor spreading, which added the oceanic

counterpart to the idea of continental drift. Together, these two

theories became united as the plate tectonic paradigm.

Ocean circulation is responsible for much of the world’s

climate. For instance, mild foggy winters in London are caused

by warm waters from the Gulf of Mexico flowing across the

Atlantic in the Gulf Stream to the coast of the British Isles.

Large variations in ocean and atmospheric circulation patterns

in the Pacific lead to alternating wet and dry climate conditions

known as El Niño, and La Niña. These variations affect Pacific

regions most strongly but are felt throughout the world. Other

movements of water are more dramatic, including the sometimes

devastating tsunami that may be initiated by earthquakes,

volcanic eruptions, and giant submarine landslides. Two of the

most tragic tsunami in recent history were generated by the

eruption of the Indonesian volcano Krakatau in 1883, and by

an earthquake in Indonesia in 2004. When Krakatau erupted, it

blasted out a large part of the center of the volcano, and seawater

rushed in to fill the hole. This seawater was immediately

heated and it exploded outward in a steam eruption and a huge

wave of hot water. The tsunami generated by this eruption

reached more than 120 feet (36.5 m) in height and killed an

estimated 36,500 people in nearby coastal regions. In 1998 a

catastrophic 50-foot (15-m) high wave unexpectedly struck

Papua New Guinea, killing more than 2,000 people and leaving

more than 10,000 homeless. The December 2004 Indian Ocean

tsunami generated by a magnitude 9.0–9.2 earthquake in Sumatra

was more destructive, killing an estimated 300,000 people.

The oceans are full of rich mineral deposits, including oil

and gas on the continental shelves and slopes, and metalliferous

deposits formed near mid-ocean ridge vents. Much of the

world’s wealth of manganese, copper, and gold may lie on the

seafloor. The oceans also yield rich harvests of fish, and care

must be taken that we do not deplete this source. Sea vegetables

are growing in popularity and their use may help alleviate

the growing demand for space in fertile farmland. The oceans

may offer the world a solution to growing energy and food

demands in the face of a growing world population. New lifeforms

are constantly being discovered in the depth of the

oceans and we need to take precautions to understand these

creatures, before any changes we make to their environment

causes them to perish forever.

See also OCEAN BASIN; OCEAN CURRENTS; OCEANIC

CRUST; PLATE TECTONICS.

Title Post:
Rating: 100% based on 99998 ratings. 99 user reviews.
Author:

Terimakasih sudah berkunjung di blog SELAPUTS, Jika ada kritik dan saran silahkan tinggalkan komentar