Editing Langjökull (section)

==Volcanism==
[[Image:Hveravellir 01.jpg|thumb|Hveravellir]]
[[Image:Hveravellir 02.jpg|thumb|At Hveravellir]]
Under Langjökull there are volcanoes with several components. The calderas can easily be seen from the air. The best known of these is [[Hveravellir]] with its hot spring and high temperature area to the east of the glacier. During an Ice Age some [[shield volcano]]es of this system covered the plains with lava in the region of today's [[Kjölur]] mountain road: the ''Kjalhraun'' ({{IPA|is|ˈcʰalˌr̥œyːn|}}; ''hraun'' means "lava field"). Some of this lava field is about 7,800 years old.<ref>{{cite gvp|name=Oddnýjarhnjúkur-Langjökull|vn=371080|access-date=2024-05-01}}</ref>

A smaller volcanic system lies to the north-west of the glacier in the {{ill|Arnarvatnsheiði|is}} {{IPA|is|ˈa(r)tnarˌvasːˌheiːðɪ|}}, north of the glacier [[Eiríksjökull]]. About 1,000 years ago, the craters of this system produced the lava field ''Hallmundarhraun'' {{IPA|is|ˈhatl̥ˌmʏntar̥ˌr̥œyːn|}} which extends some {{cvt|50|km}} westward into the valley of the Hvítá, and is traversed by underground streams which emerge at the waterfalls of [[Hraunfossar]] not far from [[Húsafell]].

Another volcanic system to the south-west of Langjökull is [[Presthnúkur]], named after its [[central volcano]], a [[rhyolite]] [[lava dome|dome]] with a high temperature area at its foot. Its fissures extend under Langjökull.

Volcanically, the region is relatively quiet, compared to other regions in Iceland, with just 32 eruptions in the last 10,000 years.<ref>[http://www.mantleplumes.org/Penrose/PenPDFAbstracts/Jakobsson_Sveinn_abs.pdf Sveinn Jakobson u.a., Volcanic systems and segmentation of the plate boundaries in S-W-Iceland]</ref>