What is a contintal drift?

Answer 1

The Theory That There Was Once A Super Continent Called Pangea. Pangea Later Broke Apart And It's Pieces Drifted Away From One Another. Now They Are In The Position That We See Today.

or

Continental drift is the movement of theEarth's continents relative to each other

Close examination of a globe often results in the observation that most of the continents seem to fit together like a puzzle: the west African coastline seems to snuggle nicely into the east coast of South America and the Caribbean sea; and a similar fit appears across the Pacific. The fit is even more striking when the submerged continental shelves are compared rather than the Coastlines

In 1912 Alfred Wegener (1880-1930) noticed the same thing and proposed that the continents were once compressed into a single protocontinent which he called Pangaea (meaning "all lands"), and over time they have drifted apart into their current distribution. He believed that Pangaea was intact until the late Carboniferous period, about 300 million years ago, when it began to break up and drift apart. However, Wegener's hypothesis lacked a geological mechanism to explain how the continents could drift across the earths surface as he proposed.

Searching for evidence to further develop his theory of continental drift, Wegener came across a paleontological paper suggesting that a land bridge had once connected Africa with Brazil. This proposed land bridge was an attempt to explain the well known paleontological observation that the same fossilized plants and animals from the same time period were found in South America and Africa. The same was true for fossils found in Europe and North America, and Madagascar and India. Many of these organisms could not have traveled across the vast oceans that currently exist. Wegener's drift theory seemed more plausible than land bridges connecting all of the continents. But that in itself was not enough to support his idea. Another observation favoring continental drift was the presence of evidence for continental glaciation in the Pensylvanian period. Striae left by the scraping of glaciers over the land surface indicated that Africa and South America had been close together at the time of this ancient ice age. The same scraping patterns can be found along the coasts of South America and South Africa.

Wegener's drift hypothesis also provided an alternate explanation for the formation of mountains (orogenesis). The theory being discussed during his time was the "Contraction theory" which suggested that the planet was once a molten ball and in the process of cooling the surface cracked and folded up on itself. The big problem with this idea was that all mountain ranges should be approximately the same age, and this was known not to be true. Wegener's explanation was that as the continents moved, the leading edge of the continent would encounter resistance and thus compress and fold upwards forming mountains near the leading edges of the drifting continents. The Sierra Nevada mountains on the Pacific coast of North America and the Andes on the coast of South America were cited. Wegener also suggested that India drifted northward into the Asian continent thus forming the Himalayas.

Wegener eventually proposed a mechanism for continental drift that focused on his assertion that the rotation of the earth created a centrifugal force towards the equator. He believed that Pangaea originated near the south pole and that the centrifugal force of the planet caused the protocontinent to break apart and the resultant continents to drift towards the equator. He called this the "pole-fleeing force". This idea was quickly rejected by the scientific community primarily because the actual forces generated by the rotation of the earth were calculated to be insufficient to move continents. Wegener also tried to explain the westward drift of the Americas by invoking the gravitational forces of the sun and the moon, this idea was also quickly rejected. Wegener's inability to provide an adequate explanation of the forces responsible for continental drift and the prevailing belief that the earth was solid and immovable resulted in the scientific dismissal of his theories.

In 1929, about the time Wegener's ideas began to be dismissed, Arthur Holmes elaborated on one of Wegener's many hypotheses; the idea that the mantle undergoes thermal convection. This idea is based on the fact that as a substance is heated its density decreases and rises to the surface until it is cooled and sinks again. This repeated heating and cooling results in a current which may be enough to cause continents to move. Arthur Holmes suggested that this thermal convection was like a conveyor belt and that the upwelling pressure could break apart a continent and then force the broken continent in opposite directions carried by the convection currents. This idea received very little attention at the time.

Not until the 1960's did Holmes' idea receive any attention. Greater understanding of the ocean floor and the discoveries of features like mid-oceanic ridges, geomagnetic anomalies parallel to the mid-oceanic ridges, and the association of island arcs and oceanic trenches occurring together and near the continental margins, suggested convection might indeed be at work. These discoveries and more led Harry Hess (1962) and R.Deitz (1961) to publish similar hypotheses based on mantle convection currents, now known as "sea floor spreading".

Answer 2

find out under heading techtonic plates, may be another theory since i learnt this stuff the big is the same as the small look out at cosmos what you see is how fantastic your abilty of your preception is no limit.

Answer 3

Continental drift is the movement of the Earth's continents relative to each other, thus appearing to "drift" across the ocean bed. The speculation that continents might have 'drifted' was first put forward by Abraham Ortelius in 1596.

Answer 4

Continental drift is the theory that Earth's continents have moved over geological time due to the movement of tectonic plates. This movement has caused continents to drift apart or come together, leading to the current positions of landmasses on Earth.

Answer 5

continential drift means that the world was once together but due to faults earth started drifting apart

Answer 6

states platforms move

Answer 7

it is where a bit of land moves over time