Fagradalsfjall’s summit stands about 820 feet (250 meters) above sea level. The volcano covers an area about 4 miles (6 km) wide made up of tuyas (flat-topped, steep-sided volcanoes that erupt through glacier ice), mounds and ridges composed of hyaloclastites (a pillow-like igneous breccia made of basalt fragments), and postglacial lavas.