Tindfjallajökull

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Tindfjallajökull is a glacier in southern Iceland, and the name also refers to the underlying stratovolcano. The glacier sits on the Mid-Atlantic Ridge, with the Tindfjöll mountain ridge extending to the south.

The highest point is Ýmir, at 1,462 meters (4,797 feet). The glacier covers about 300 square kilometers (120 square miles). The central volcano is about 15–20 kilometers across and has a caldera roughly 5 by 7 kilometers in size, with rocks ranging from basaltic to rhyolitic. There are eight tuyas (flat-topped, lava-formed mountains) in the system. The largest is the Thórólfsfell tuya, on the southern flank, about 8 square kilometers in area and with a prominence of around 450 meters.

The most recent eruptions are thought to have occurred in the Holocene, with older mountain-building eruptions well before 55,000 years ago. The Thórólfsfell tuya is the classic example of a tuya, formed under ice without a long-lasting meltwater lake. Northeast of the glacier is Sultarfell, a pale rhyolitic hill, and Hitagil to the southeast has a hot spring, showing ongoing geothermal activity.

Glaciation and change: the glacier has retreated significantly since the late 19th century. It feeds several outlet glaciers, including an unnamed outlet in Eystri Botná valley, and nearby Blesárjökull. A branch north of Ýmir has split into three, and Ýmujökull on the eastern slopes has disappeared. Water from the glaciers feeds rivers such as Hvítmaga and Gilsá to the northeast, and Þórólfsá, Valá, and Blesá to the south and west; these rivers drain into Markarfljót and Eystri Rangá.