Hafnarfjall
| Hafnarfjall | ||
|---|---|---|
 View from Borgarnes to Hafnarfjall |
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| height | 844 m | |
| location | Iceland | |
| Coordinates | 64 ° 29 ′ 51 ″ N , 21 ° 52 ′ 50 ″ W | |
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| Type | volcano | |
| rock | predominantly basalt | |
| Last eruption | approx. 4 million years ago (inactive) | |
| Normal way | Hiking trail on the north side | |
 Hafnarfjall in winter |
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Hafnarfjall Mountain is a cold volcano in Iceland . It is located on Borgarfjörður in the west of the country opposite the town of Borgarnes and belongs to the municipality of Borgarbyggð . Hafnarfjall is 844 m high.
What is striking about it are the erosion slopes , especially to the northwest. However, the Icelandic forest administration has made successful efforts in the last few years to plant these slopes with beach grass and to strengthen them with it. The mountain consists mainly of black basalt , parts of it also of rhyolite , as can be seen from the small ravines that cut into the mountain.
Granophyrintrusion: Flyðrur
Not far from the bridge over Borgarfjörður you can see rocks of different colors in the black basalt erosion slopes limited to a small patch. These have roughly the shape of flounders and that's why they are called: Flyðrur . They are an intrusion from Granophyr . The eroded material below them leaves a strikingly bright trail in the black rubble all around.
The central volcano
The mountain, together with the neighboring higher mountain range of Skarðsheiði, is the remnant of a large central volcano that was active around 5.5-4 million years ago. Dykes attest to the development of magma chambers .
There are four different eruption phases of the volcano: the first on Brekkufjall, the second on Hafnarfjall itself, the third on Skarðsheiði, the fourth on Heiðarhorn (Skarðsheiði).
In the first phase more basaltic material was ejected, in the second intermediate and finally rhyolite material. During the third phase there was also the production of pyroclastic currents , traces of which can be found among others. a. at Andakíll can be seen as very ferrous and therefore reddish ignimbrite . It is believed that basaltic magma penetrated the chamber filled with rhyolite magma, causing overheating, as well as the production and ejection of the ignimbritic material.
When Brekkufjall , an upstream small mountain in Andakíll at Hvanneyri , which adjoins in the east to the Hafnarfjall, it is a solidified lava with later intrusions from the central volcano.
Traffic obstruction
Hafnarfjall can sometimes develop into a traffic obstacle when, especially in winter, the dreaded down winds hit the ring road below it and sometimes even sweep cars off the road. Wind speeds of (in gusts) over 50 m / s are measured from time to time, but in winter the road sometimes has to be closed even with snowfall and wind speeds of over 20 m / s.
See also
Web links
- Hjalti Franzson: An Ignimbrite Cone-Sheet Feeder in The Hafnarfjall-Skarðsheiði Central Volcano, W-Iceland , in: George PL Walker Symposium on Advances in Volcanology, International Association of Volcanology and Chemistry of the Earths Interior (IAVCEI), Reykholt, Borgarfjordur, 12-17 June 2006, p.55 (About the central volcano Hafnarfjall - Skarðsheiði) (Abstract, English)
- L. Kristjánsson, ea: Paleomagnetic Studies in Skarðsheiði, South-Western Iceland. Jökull 50 , 33-48, 2001. (Abstract, English)
- Icelandic road watch, Hafnarfjall monitoring station
Individual evidence
- ^ HU Schmid: Dictionary Icelandic - German. Buske, Hamburg, 2001, 70
- ↑ Íslandshandbókin. Náttúra, saga og sérkenni. 1. bindi. Edited by T. Einarsson, H. Magnússon. Örn og Örlygur, Reykjavík 1989, p. 106.
- ↑ Archive link ( Memento of the original from July 9, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Hjalti Franzson, ISOR Iceland GeoSurvey, Iceland: An ignimbrite cone-sheet feeder in The Hafnarfjall-Skardsheidi central volcano W-Iceland, in: IAVCei. A George PL Walker Symposium on Advances in Volcanology. Reykholt, Borgarfjordur, W-Iceland, 12. – 17. June 2006; Accessed: August 20, 2010 [PDF file] (English)
- ↑ Freysteinn Sigurðsson: Borgarfjarðarhérað milli Mýra og Hafnarfjalla. Ferðafélag Íslands, árbók 2004. Reykjavík 2004, p. 68
- ↑ cf. http://www.mbl.is/mm/frettir/innlent/2010/02/25/ofaert_undir_hafnarfjalli/ Ófært undir Hafnarfjalli. mbl.is, February 25, 2010; Accessed October 20, 2010 (Icelandic)
