A maar is a low relief volcanic crater produced by the interaction of rising magma and ground water and the product is shallow explosive eruptions. What happens is the heating and boiling of ground water when magma invades the ground water table and the explosions blast up through the surface. The result is a crater that looks similar to a hole that is often filled with water to form a lake. The range in size is from across and form . There are maars in western USA, in the Eifel region of Germany and in geologically young volcanic region of the world, one of them is Hunt's Hole and Kilbourne Hole located in Potrillo volcanic field, in Dona Ana New Mexico close to El Paso Texas. There are five maars in the Potrillo volcanic field.