Phreatomagmatic eruptions occasionally create broad, low-relief volcanic craters called maars.[12] These explosion craters are interpreted to have formed above rubble-filled volcanic pipes called diatremes; deep erosion of a maar presumably would expose a diatreme.[13] Maars range in size from 61 to 1,981 metres (200–6,499 ft) across and from 9 to 198 metres (30–650 ft) deep and are commonly filled with water to form a crater lake.[13] Fiftytwo Ridge at the southeastern end of Wells Gray Provincial Park in southeastern British Columbia is an example of a volcano containing lake-filled maars.[14] Most maars have low rims composed of a mixture of loose fragments of volcanic rocks and rocks torn from the walls of the diatreme.[13] Phreatic explosions can be accompanied by carbon dioxide or hydrogen sulfide gas emissions.[15] Subglacial eruptions Subglacial eruption: 1: water vapor cloud, 2: lake, 3: ice, 4: layers of lava and ash, 5: strata, 6: pillow lava, 7: magma conduit, 8: magma chamber, 9: dike Subglacial eruptions occur when lava erupts under large portions of glacial ice.