why do continents drift?

Answer 1

Really, the answer to your question is simply: Plate Tectonics. Read below for details.

Earthquakes:
It all comes down to stress and strain from the interaction of different plates, chiefly at the boundaries. It is not 'the plates rubbing together' as many people say; or at least that's a very simplistic view.

Plate tectonics causes stress on the continents and oceans, all over the surface of the earth. In some places, the stress is very small (usually within the plates). Elsewhere, the stress is high, usually where the plates meet each other. Since each plate moves, when two come in contact, the stress each other. They can push on each other and cause compressional stress, they can pull with extensional stress, and they can slide past or shear each other with tensional stress.

Faulting, causing earthquakes, comes from the fact that this stress is building up all the time, but rocks and continents are strong materials. Just like hitting a rock with a small hammer, you do put stress on it, but a small amount. It would take a sledgehammer to put enough strain (effects and accumulation of stress) to build up and cause breakage. In the earth, the area around an active fault builds up strain from the stress of plate tectonics. Most faults become locked, because of this strength, and thus can not release their strain. Away from the fault, the stress produces very small and slow movement of the rock masses as a whole. Eventually, the strain is too much and the rest of the plate has moved too far and the fault releases the strain build-up all at once in a big stress release called an earthquake. This is called the elastic rebound theory, and it explains most (but not all) movements.

This is why an earthquake's size is relative to the fault size. The bigger the fault, the bigger the strain build up, and the bigger the release in an earthquake. Subduction zones and collision zones, where large portions of plates actually can rub together as a whole, have the really big earthquakes, like the 2004 Sumatra earthquake. In other plate boundaries, the entire plate boundary does not act together, so the faults become spread out and many faults take up the strain from the tectonic stress, like with the San Andreas Fault in California (it only takes up ~3/4 of the stress between the plates).

Earthquakes are really tricky things; there is still so much we need to learn. As of now, there is no way to predict them, but we can say where the danger is highest and about how long between events.

Volcanoes:
There are several processes in Plate Tectonics that cause volcanism, but they result in two main types of volcanism.

Volcanism in subduction is caused by volitals, like H2O, CO2. These are carried down by the plate, mainly in the form of weak minerals. These minerals break down with pressure and temperature into stronger minerals that don't contain water and carbon dioxide. The leftover gases and liquids travel into the mantle (the mantle wedge) and hydrate the mantle, causing melting. The melt rises and then... volcano!

The other main cause is from rising mantle material, which forms decompression melting. Basically, hot mantle is kept from melting by the pressure of the earth at depth. When this material rises, the pressure drops much faster than the temperature, and thus it partially melts. This mainly occurs at divergent boundaries and hot spots, which are areas in plate tectonics that have rising materials or spreading.

Mountain Belts:

Non-volcanic mountain belts are caused by compressive stress in plate tectonics. This can be 1. fold and thrust belts in highly compressive subduction zones (almost always from oceanic beneath continental subduction, e.g. east Andes, Rockies) or 2. continental-continental collisions (e.g. Himalaya, Appalachian).

Answer 2

Continents drift because center of the earth is very hot, and the contenents are ultimately sitting on hot liquid rock.

Think about a lava lamp. The wax goes up, cools down, and then sinks and is heated up again.

This is happening all the time inside the earth. Of course, rock is a lot thicker than water or wax and the distance the liquid is flowing is massive (thousands of miles) but naturally the contenents are being pushed in various directions.

Answer 3

because they pull the handbrake, then slam on the accelerator when turning into a corner? lol

the earth has a molten core, the molten core has currents, the currents cause the earths crust to move, that movement is called continental drift.
The molten core of the earth has several layers, each layer has it's own name. Each layer is made of a different material, they say that the very centre of the earth is molten iron because it is heavvy it would sink to the bottom.
The currents of the molten core are caused by variations in temperature, hot things rise while cool things sink, at the centre of the earth, ther is a lot of pressure caused by gravity, all this pressure causes a lot of heat, so the core is hotter at the core than it is at the surface. Once the molten stuff rises to the earths crust, its temperature decreases and the stuff sinks back down towards the centre where it heats up again. ( the stuff has different names depending on which layer it is in, near the surface, it is called magma, once it comes out onto the surface it is called lava)
The continents are plates of rock which have not been heated enough to be molten, so they float on top of the molten stuff, and any currents that exist in the molten stuff will affect the movement of the plates / coninents which are sitting on top, kind of like a leaf floating on the surface of a river.
There are so many places that you should be able to look this up, on the internet and in your local library. Unless you are some university professor who is doing some kind of social experiment.

Answer 4

Just lack of get-up-and-go, I guess.

Or maybe it's because the continents all ride on plates which are in constant motion with respect to each other, not only along the surface, but also sliding beneath one another, So, the plates carry the continents, which along for the ride, sort of willy-nilly fashion.

Answer 5

Plate tectonics. A more dense plate slides beneath a less dense plate (in a process called subduction). As the more dense plate moves, the crust is opened up (by sea-floor spreading), allowing magma to rise and form new crust. This rising and sinking of magma causes convection in the mantle, moving the plates along with the convection currents.

Answer 6

scientists belive in the theory called plate tectonics, it explains how the continents used to all be one known as pangea. over time the plates moved apart, also ripping apart pangea. if you look at a world map you can see how it looks like some of the continents used to fit together, so plate tectonics is the only reasonable explaination

Answer 7

See this article on Wikipedia:

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

Answer 8

because they get bored