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.
Earth's crust â the lithosphere â is composed of several major plates and many minor plates that change shape and position. Over time, these tectonic plates move, interact with each other, and are responsible for the formation of ocean basins, mountain ranges, islands, volcanoes, and earthquakes. The theory of plate tectonics is relatively new.