Búrfell () and the connected lava channel Búrfellsgjá are famous and protected landmarks of the Reykjanes peninsula, Southwest Iceland. They are part of the Krýsuvík volcanic system.
Name The name Búrfell is widespread in Iceland. It means "pantry mountain"
Pyroclastic cone Búrfell The spatter cone BúrfellThor Thordarson, Armann Hoskuldsson: Iceland. Classic geology in Europe 3. Harpenden 2002, p.60 is located at about from Hafnarfjörður in Heiðmörk,Björn Hróarsson: Hellahandbókin. Leiðsögn um 77 íslenskra hraunhellir. Reykjavík 2008, p. 56 part of the Krýsuvík volcanic system. and its northernmost outpost as a volcano. The volcanic cones sits on older lava layers, the Tertiary Grey Basalt lavas which are the basement rocks of the area of Heiðmörk.Thor Thordarson, Armann Hoskuldsson: Iceland. Classic geology in Europe 3. Harpenden 2002, p.59
It originated in an eruption series from the same source. When these eruptions took place is still discussed, M. Traustadóttir proposes a date about 7300 years ago, other scientists argue that it was over 8000 years ago
The Búrfell cone has a near-circular form "with ramparts made up almost entirely of spatter ejected by lava fountains". The 80 m high crater rims enclose a 60 m and 140 m wide crater. During the eruption, it contained a lava lake.
Búrfell is an exception in the volcanic landscape of the Reykjanes peninsula in Southwest Iceland, as it is not part of a cone row, but an isolated monogenetic cone, which nevertheless produced a long drawn-out eruption series and a rather big lava field reaching down to the sea at many places and under many names, between Hafnarfjörður and Straumsvík as well as in Álftanes into Skerjafjörður.
Lava field Búrfellshraun The lava field Búrfellshraun has an area of , an approxiamate volume of and extends about , so is one of the larger lava fields on the Reykjanes peninsula. The lavas are today partially covered up by structures and another part of them lies under seawater in the fjords Skerjafjörður and Hafnarfjörður, as the sea water level at time of eruptions was lower than it is today.
Whereas the geologic denomination is Búrfellshraun for all the lava of the eruption, the locals, depending on the region, use different names. The branches in direction of Skerjafjörður e.g. are called Urriðakotshraun , Vífilsstaðahraun and Gálgahraun (, "Gallow's lava").
Lava channels of Búrfellshraun The lava channels (and lava tubes) built up the different episodes of the eruption.
Progression of the eruption and formation of lava channels At the eruption start, the Kaldársel branch of lava ran to the southwest, following the orientation of a fault system in the region, the Hjallar faults. At Kringlóttagjá a lava pond formed when the lava flow was stopped temporarily by topography. Until then, the lava transport had taken place in open channels. The lava flow advanced then towards Kaldársel where today there is a hut and parking area for hikers,Reynir Ingibjartsson: 25 Gönguleiðir á Reykjanesskaga. Náttúrann við Bæjarveggin. Reykjavík , p.11 and from there towards the north, fed by Kringlóttagjá lava pond. There lava tubes formed.
Búrfellsgjá The lava channel Búrfellsgjá which reaches from the crater in northwestern direction, is said to have built up, when there was a lava lake overflow. After some time, the lava production stopped suddenly and this is the reason why the lava channel is still so well preserved.
As the Krýsuvík system had undergone a number of earthquake series in the years before 2012, levelling measurements were carried out in Búrfellsgjá in this year and compared to others from the years before. These measurements showed subsidence which could possibly be explained by extension movements of the fissure system.
Other lava channels Another lava channel reaches west from Búrfell in direction of Kaldársel, but as it is filled up with lava, it is not easily found as a landscape feature. This is the oldest lava channel, it is named Lambagjá (, "lamb canyon"), the youngest is Kringlóttagjá (, "round canyon") south of Búrfellsgjá, where there was also a lava pond.
Lava tubes of Búrfellshraun Two lava tubes are described in connection with Búrfellshraun: and . Both lava tubes are branches of Búrfellsgjá, in western direction, with one showing well preserved lava formations.Björn Hróarsson: Hellahandbókin. Leiðsögn um 77 íslenskra hraunhellir. Reykjavík 2008, p. 57
Hiking Partially marked hiking trails lead from Route 408 into Búrfellsgjá and up on Búrfell.
Protected Area
This area of Garðabær municipality became a protected natural monument on June 25th 2020.
External links Margrét Traustadóttir : Hallarmælingar í Búrfellsgjá, sumarið 2012. BS ritgerd. Jarðvísindadeild Háskóla Íslands. Leiðbeinandi Sigrún Hreinsdóttir. (2013) (Text mostly in Icelandic, abstract also in English.)
References