The crossword solution for the term 'ERUPTION SIGHT' is 'MAGMA'. MAGMA is molten rock that is found beneath the Earth's surface. It is formed by the melting of rocks due to the extreme temperatures and pressures found deep within the Earth. When MAGMA reaches the surface, it is known as lava and can cause an eruption. Therefore, an eruption sight is a place where MAGMA has reached the surface and caused an eruption.