Sunday, November 27, 2005

Continental Drift

I remember while I was in school studying 8th standard, I was observing world map and suddenly felt that the continents (land mass) which look apart now might have been once a complete piece of one single land mass and was looking for other parts in the map if they would match, but felt that there are few similarities on the border to match but not exact pen-cap fitting and came to a conclusion that it could be because of the continuous hitting of water for ages that the land mass got corrored on the border and hence the boundries dont match but it planted deeply in my mind that it was ineed a complete one piece of land mass, and the same I told to my teacher and friends. The reason is while observing South America and Africa it seemed it fitted well and island Madagascar fitted well to the border of Africa. I was just put down that time and after that although I finished lot of years, this thing remained strong in my mind for which I found an article now, which I posted below called "Continental Drift" which matches my thoughts.

http://en.wikipedia.org/wiki/Tectonic_plates

Tectonic plate
From Wikipedia, the free encyclopedia.
(Redirected from Tectonic plates)
Jump to: navigation, search

The tectonic plates of the world were mapped in the second half of the 20th century.
A Tectonic plate is a piece of the Earth's crust (or lithosphere). The surface of the Earth consists of seven major tectonic plates and many more minor ones.
The plates are around 100 km (60 miles) thick and consist of two principal types of material: oceanic crust (also called sima) and continental crust (sial). Under both lies a relatively plastic layer of the Earth's mantle called the asthenosphere, which is in constant motion. This is in turn underlaid by a solid layer of mantle.
The composition of the two types of crust differs markedly. Oceanic crust consists largely of basaltic rocks, while the continental crust consists principally of lower density granitic rocks rich in aluminium and silica. The two types of crust also differ in thickness, with continental crusts considerably thicker than oceanic.
The churning of the asthenosphere carries the plates along in a process known as continental drift, which is explained by the theory of plate tectonics. Interaction between the plates creates mountains and volcanoes, as well as giving rise to earthquakes and other geological phenomena.
The boundaries of the plates do not coincide with those of the continents. For instance, the North American Plate covers not only North America but also Greenland, far eastern Siberia and northern Japan.
As far as is known, the Earth is the only planet in the Solar System to possess tectonic plates, although there have been suggestions that Mars may also have possessed plates in the past before the planet's crust froze in place.


http://en.wikipedia.org/wiki/Continental_drift

Continental drift
From Wikipedia, the free encyclopedia.
Jump to: navigation, search

Portrayal of shifting continents
The concept of continental drift was first proposed by Alfred Wegener. In 1912 he noticed that the shapes of continents on either side of the Atlantic Ocean seem to fit together (for example, Africa and South America). Francis Bacon, Antonio Snider-Pellegrini, Benjamin Franklin, and others had noted much the same thing earlier. The similarity of southern continent fossil faunas and some geological formations had led a relatively small number of Southern hemisphere geologists to conjecture as early as 1900 that all the continents had once been joined into a supercontinent known as Pangaea. The concept was initially ridiculed by most geologists, who felt that an explanation of how a continent drifted was a prerequisite and that the lack of one made the idea of drifting continents wholly unreasonable. The theory received support through the controversial years from South African geologist Alexander Du Toit as well as from Arthur Holmes. The idea of continental drift did not become widely accepted as theory until the 1950s in Europe. By the 1960s, geological research conducted by Robert Dietz, Bruce Heezen, and Harry Hess along with a rekindling of the theory including a mechanism by J. Tuzo Wilson led to acceptance among North American geologists.
The hypothesis of continental drift became part of the larger theory of plate tectonics. This article deals mainly with the historical development of the continental drift hypothesis before 1950. See: plate tectonics for information on current ideas underlying concepts of continental drift.

http://upload.wikimedia.org/wikipedia/en/8/8e/Pangea_animation_03.gif


Current Major Plates
African Plate
Antarctic Plate
Arabian Plate
Australian Plate
Cocos Plate
Eurasian Plate
India Plate
Indo-Australian Plate
Nazca Plate
North American Plate
Pacific Plate
Philippine Plate
Scotia Plate
South American Plate
[edit]

Current Minor Plates
Adriatic Plate
Amurian Plate
Anatolian Plate
Bismark Microplate
Burma Plate
Caribbean Plate
Caroline Plate
East American Plate
Easter Microplate
Explorer Plate
Fiji Microplates
Galapagos Microplate
Gorda Plate
Hellenic Plate
Iberian Plate
Iranian Plate
Juan de Fuca Plate
Juan Fernandez Microplate
Okhotsk Plate
Rivera Microplate
Somali Plate
South Sandwich Plate
Sunda Plate
Tonga Plate
[edit]

Ancient Plates
Farallon Plate
Kula Plate

Comments: Post a Comment

Subscribe to Post Comments [Atom]





<< Home

This page is powered by Blogger. Isn't yours?

Subscribe to Posts [Atom]