Forward Backward continental drift Continental drift is the movement of the Earth's continents. The land masses are hunks of Earth's crust that float on the molten core. The crust of the Earth is broken into plates . The plates are enormous chunks of rock that float atop the soft mantle. The plates are moving at a speed that has been estimated at 1 to 10 cm per year.
Continental plates are thicker, older, and less dense than oceanic plates.
These plates are about 125 kilometers thick and are made of granite that is about 3 billion years old. The continental shelf is the part of the ocean floor next to each of the continents. Beyond the continental shelf the sea floor drops steeply. This force has effects on water currents, but has no effect on the direction of water going down a drain. A crater is a circular depression in the ground.