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.
Tectonic plates move because of convection currents. These convection currents happen in the mantle, underneath the tectonic plates. The heat, which causes the convection currents, is produced from the radioactive decay left over from the Earths formation.