How were the continents formed?

Question

Meaning the continental and oceanic crusts themselves, not the shapes of them as we see them today.

Answer 1

in the beginning there was just one continent Pangea.

What we need to see now is what was happening under the crust.

As we know the crust was broken up into various plates. Underneath magma was moving because of convectional currents. these convectional currents rose up and then went down in a circular fashion.

This made the various plates move apart and also move against each other.

This separated Pangea into the continents as we see them today

Answer 2

They formed over millions of years from extremely active super volcanos when they earth was still young,  the extremem heat of the earths core caused billions of tons of rock to come out of the earth and cool in the sea's water creating the land masses we have today.

Hawaii is a good "today" picture of what happened thouse millions of years ago

Answer 3

They were formed by the activities of tectonic plates.

The continental Drift theory explains that milleniums before there was a single landmass which later formed Gondwanaland and Laurasia by the shifting of plates and later they formed the present continents

Answer 4

Oceanic crust is formed by the intrusion of magma and extrusion of lava at ocean spreading ridges where two plates are pulling apart.

Continental crust is thicker and with a different less dense overall composition than oceanic crust. The first bits of continental crust must have formed at convergent boundaries between oceanic plates. As one plate dove below the other, an island arc volcanic system was created above the subduction zone. The volcanoes and the magma beneath them  would have become enriched with silica and aluminum relative to the more Fe and Mg enriched chemistry of oceanic crust. This would be the very beginnings of continental-type crust. Because the arc system had a different chemistry, it was less dense than oceanic crust. It wouldn't easily subduct and get recycled in the manner that oceanic crust is. Instead, over a long period of time, the bits of continent-like regions would actually grow by adding on new igneous rocks at convergent plate boundaries. They also grew by adding on sedimentary rocks at plate boundaries: Assuming that the island arc system built up high enough to form islands, erosion of material off the islands would have formed a fringe of sandy sediments around them. Some of the sediments might have been transported into the subduction zone, and then been plastered onto the edge of the island arc system by convergent plate motions.  

Then, supposing these mini-continents collided with one another--the collision would suture them together, creating a bigger block of continent-like material. In addition, the collision would trap some ocean crust, thus making the pile of "stuff" even bigger.

Major collisions, and processes at convergent boundaries, create enough pressure and temperature to convert some of the igneous and sedimentary rocks of the baby continents to metamorphic rocks. So, continents have a much more complex mixture of rock types, and a much longer history than any oceanic plate.

The very oldest cores of the continents are called the "craton". They are at least 500 million years old, some are as old as 2 billion years old.The second url below says more about them, and shows a map of their locations within the bigger modern continents. There is also a more technical description of craton formation than the one I just gave.

The megacontinents of Pangea, Gondwana, Laurasia referred to in some answers above developed millions of years later in time, around the cores of ancient cratons.