Wikipedia
Torfajökull
Torfajökull ( Icelandic for "Torfi's glacier") is a rhyolitic stratovolcano and complex of subglacial volcanoes, located north of Mýrdalsjökull and south of Þórisvatn Lake, Iceland. Torfajökull last erupted in 1477 and consists of the largest area of silicic extrusive rocks in Iceland.
The volcano's eruption around 870 has left a thin layer of tephra all over Iceland. This layer makes possible to determine the exact dates of many archeological finds, like in the Reykjavík 871±2 museum.