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.
Plate movement causes the buildup of tremendous quantities of energy in the rock. When the energy is released, it produces vibrations that travel through the rock, leading to earthquakes. During earthquakes, faults, or giant cracks, are produced by the pressure of the moving rock. Earthquakes and volcanoes occur along the edges of the plates. Scientists have developed a theory that explains how these giant plates move, thereby creating, destroying, and re-forming continents and oceans over long periods of time. This theory is called the theory of plate tectonics.