a branch of the Indo-European family of languages, including especially Irish, Scottish Gaelic, Welsh, and Breton, which survive now in Ireland, the Scottish Highlands, Wales, and Brittany. adjective. 2. of the Celts or their languages.
Movement of tectonic plates-higher. Volcanoes, mountains and earthquakes occur at the edges of tectonic plates-their creation depends on the direction the plates are moving.
The movement of the plates is caused by the convection currents of heat from the Earth's interior. This heat, rising toward the surface through the mantle causes movement of plastic like rock in the asthenosphere, the layer of Earth directly below the lithosphere.he Earth's plates are riding on top of the currents caused by these processes. The main features of plate tectonics are: 1  The Earth's surface is covered by a series of crustal plates. 2  The plates are composed of crustal rock and solid upper mantle which is called the lithosphere.