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.
Theory of Plate Tectonics The theory that states that Earth's lithosphere is made up of huge plates that move over the surface of the Earth. One plate cannot move without affecting the others nearby. The plates can move apart, push together, or scrape past each other. Plate movements cause most major earthquakes, volcanoes and mountain ranges.