Volcanoes can be formed by plumes of magma originating in this layer of the Earth below the crust
[DOC] [TLE] hot spot - National Geographic Society [PAR] Dec 17, 2014 ... A hot spot is a region deep within the Earth's mantle from which heat rises by ... 
Island volcanoes that form over hot spots are generally less ... as magma, often 
pushes through cracks in the crust to form volcanoes.