Rauðhólar (Vesturdalur) is a small chain of volcanoes within the

Askja Askja () is an active volcano situated in a remote part of the central highlands of Iceland. The name Askja refers to a complex of nested calderas within the surrounding Dyngjufjöll mountains, which rise to , ''askja'' meaning ''box'' or ' ...

or the

Fremrinámur Fremrinámur () is a volcano with a located on the basalt plateau in Iceland. It is at the junction of the Mid-Atlantic Ridge and the Greenland–Iceland–Faeroe Ridge. It is one of five volcanic systems found in the axial rift zone in north-ea ...

volcanic systems in the north of

Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...

. They are located at the lower course of the river

Jökulsá á Fjöllum Jökulsá á Fjöllum (; "glacial river in the mountains") is the second longest river in Iceland (206 km). Its Source (river or stream), source is the Vatnajökull glacier. It flows into the Greenland Sea. Jökulsá á Fjöllum streams over ...

, around 25 km from

Öxarfjörður Öxarfjörður () is a broad fjord in northeastern Iceland, situated between the Tjörnes and Melrakkaslétta headlands. Geography Öxarfjörður is encircled by mountain ranges to the west and east, and the Gjástykki lava fields and an area ...

fjord and at the same time near

Vesturdalur Vesturdalur ("west valley") is a valley that runs from the head of Skagafjörður, Iceland and cuts far into the central Highlands of Iceland, highlands. Austurdalur valley runs parallel to it. The valleys are surrounded by tall, steep mountains ...

Jökulsárgljúfur National Park Jökulsárgljúfur National Park () is a former national park situated in the north of Iceland around the river Jökulsá á Fjöllum. It lies to the north of the Dettifoss waterfall. On 7 June 2008, it became a part of the larger Vatnajökull Nati ...

next to the ''Hljóðaklettar'' (the echo cliffs).

Geology

Hljóðaklettar and Rauðhólar

The latter vents and Rauðhólar build together a small volcanic chain, consisting of eruption fissures which were active 11.000 years ago. Some of the fissures crossed the river. The river destroyed the craters of Hljóðaklettar and only remnants were left standing, dikes,

volcanic plug A volcanic plug, also called a volcanic neck or lava neck, is a volcano, volcanic object created when magma hardens within a Volcanic vent, vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if risi ...

s, sills and

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

s. The erosion started with phreatomagmatic explosions during the eruption series, when water and magma met, but there was also steady fluvial erosion afterwards, incl. many big

jökulhlaup A jökulhlaup ( ) (literally "glacial run") is a type of glacial outburst flood. It is an Icelandic term that has been adopted in glaciological terminology in many languages. It originally referred to the well-known subglacial outburst floo ...

. The volcanic edifices of Rauðhólar on the other hand were just opened in the direction of the river, but left intact.

Jökulhlaups of Jökulsá á Fjöllum

Scientists are still discussing the exact data of the

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

volcanogenic

s of

, but it is possible to show the sedimentary record of no less than 16 jökulhlaups in Vesturdalur.

Magmatic plumbing system

The magmatic plumbing system of Rauðhólar was exposed by erosion, so that a.o. the feeder dike can be seen and analyzed whereby the geologist A. Gudmundsson saw a connection between the dike and a normal fault (re)activated by the dike movements. as this is still a location on the active Icelandic rift zone. Other scientists refer to the type of volcanoes as

scoria cone A cinder cone or scoria cone is a steep, conical landform of loose pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions or l ...

s which in this case expose a rather complicated plumbing system connected to repeated

intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

Visitor attraction

The region with its very unusual rock formations is also a visitor attraction with many hiking trails, a camping area nearby and some simple facilities.Vatnajökulsþjoðgarður. Jökulsárgljúfur. (Official website)
Retrieved 28 July 2020. The road has newly been upgraded (in 2020). The

valley and its rock formations are part of

, today integrated in the bigger

Vatnajökull National Park Vatnajökull National Park ( ) is one of three national parks in Iceland, and is the largest one. It encompasses all of Vatnajökull glacier and extensive surrounding areas. These include the national parks previously existing at Skaftafell in th ...

External sources

*Friese, N., Bense, F.A., Tanner, D.C. et al. From feeder dykes to scoria cones: the tectonically controlled plumbing system of the Rauðhólar volcanic chain, Northern Volcanic Zone, Iceland. Bull Volcanol 75, 717 (2013). https://doi.org/10.1007/s00445-013-0717-2

References

{{reflist North Volcanic Zone of Iceland Vatnajökull National Park