Iceland is located on the Mid-Atlantic Ridge as well as a hotspot. This is why Iceland is so volcanically active. The distribution of volcanism in Iceland matches the location of the Mid-Atlantic Ridge and is most active where the inferred position of the hotspot is. Consequently the youngest Icelandic rocks create a band across Iceland with ages increasing with distance away from the Mid-Atlantic Ridge. There are a number of volcanic centres across Iceland. These usually consist of both fissure swarms (chains of volcanic vents which run in the same orientation as the Mid-Atlantic Ridge) and central volcanoes which are areas of focussed volcanic activity, usually fed by a large magma chamber. Often a central volcano will consist of many separate volcanic edifices (e.g. at Torfajökull).