The international Mountain Day, 11th of December 2020, Lómagnúpur
Today is the international mountain day and therefor we in Katla Geopark wanted to share with you some information about mountains and especially about one of our favorite mountains, Mt. Lómagnúpur in Skaftárhreppur municipality.
We highly recommend that you take a look at the webpage of the Global Geoparks Network (http://globalgeoparksnetwork.org/?p=2314) where a short piece about mountainous areas was just published.
Mt. Lómagnúpur is considered by many, including the Geopark, to be one of the most beautiful mountains in Iceland. The mountain rises magnifically over the surrounding area, with the Skeiðarársandur sand plan in front of it, with the western part of Vatnajökull glacier behind it and the outlet glacier Skeiðarárjökull on its flank. Mt. Lómagnúpur is a part of a larger mountain range called Björninn, but the volcano or volcanos that built up that range are no longer active. The rock layers at the bottom of Mt. Lómagnúpur are about 2.5 million years old, while the top part is about 1 million years old. The mountain was therefor mostly formed by volcanic eruptions under the Ice age glacier, where thick palagonite- and blocky lava layers were formed during glacial periods and lava fields during interglacial periods. The stratigraphy of the mountain can be seen well at the forefront of the mountain, which is called Lómagnúpsnef (the nose of Lómagnúpur), as it is an old sea cliff. Mt. Lómagnúpur is one of several mountains that have old sea cliffs but are far inland. The reason for this is that marine erosion occurred during interglacial periods, and especially at the end of the last glaciation, when relative ocean level was much higher than it is today. The ocean level dropped soon after the end of the last glaciation and the sand plains on the south coast started to form, which left Mt. Lómagnúpur stranded far inland.
The ocean is not the only destructive force that has shaped the mountain, as both glaciers and rockslides have had their role in it as well. Even though there is no glacier there today, the evidence of glacial erosion is evident from numerous valleys cut into the mountain. The top of the mountain has also been eroded but has been ice free since the end of last glaciation. Skeiðarárjökull, a outlet glacier from the Vatnajökull glacier, is just to the northeast of it, but unable to reach the mountain. Three rivers flow in the vicinity of the mountain called Súla, Gígjukvísl and Núpsá. The first two are glacial rivers that originate from the outlet glacier, the third one used to be a glacial river but mostly discharges meteoric water now. Many glacial outburst floods have made their way over the sand plains close to the mountain and the rivers have helped distributing the rock debris that collects at the base of the mountain. The boundary between the mountain and the surrounding lowland is quite clear, especially on the east side. The rock debris is formed due to erosion of the mountain and by larger rockslides. The last large rockslide to have occurred from the mountain happened on the 7th of June 1998. On that day, several small rockslides fell from the eastern part of the mountain and closed the road leading to the Núpsstaðaskógur forest. The largest known rockslide came from the western part of the mountain is believed to have fallen in July 1789. That rockslide is called “Hlaupið” and is easily seen from Road 1. That slide was very large, about 1.5 million cubic meters and about 1200 long. There are now two ponds in the rock debris along with two palagonite boulders that were used as sheep shelters. Just north of this slide is an older slide, but when it fell is not known.
Lómagnúpsnef, the forefront of the mountain, is 671 meters high but the highest point of the mountain is 764 meters. It is possible to hike up the mountain, both from the east and west side, but the hike is not easy as the elevation gained is about 700 meters and the mountain is quite steep. The trip is well worth the effort however, as the view from the top can only be described as otherworldly, with amazing views in all directions.
It is worth mentioning that there are several beautiful mountains within Katla Geopark and many of them have hiking trails. You can access hiking trails for Mt. Lómagnúpur and other mountains here: http://www.katlageopark.com/about-katla/maps/hiking-maps/ and here: https://wapp.is/
Photograph: Lómagnúpsnef and the eastern side of Mt. Lómagnúpur. In front of the mountain flow the rivers of Núpsá and Súla. Hlaupið, the large rockslide from 1789, can be seen on the western flank of the mountain. Photograph: Þorsteinn Roy Jóhannsson
Guðmundur Kjartansson, 1968. Steinsholtshlaupið 15. Janúar 1967. Náttúrufræðingurinn, 3-4:120-169
Guttormur Sigbjarnarson, 1983. The Quaternary alpine glaciation and marine erosion in Iceland. Jökull 1:87-98
Haukur Jóhannesson 1984. Skalf þá og nötraði bærinn. Náttúrufræðingurinn, 1-2:1-4
Hjörleifur Guttormsson 1993. Við rætur Vatnajökuls. Byggðir fjöll og skriðjöklar. Árbók Ferðafélags Íslands 1993. 265 ss
Ingólfur Ísólfsson, 1989. Útsýni af Öræfajökli. Jökull, 1:99-103
Jón Jónsson, 1974. Sprungurnar í Lómagnúpi og fleira. Náttúrufræðingurinn, 1:41-44
Sigurður Steinþórsson. „Hvernig myndast standberg?“ Vísindavefurinn, 25. október 2006. Sótt 10. desember 2020. http://visindavefur.is/svar.php?id=6336.
Snorri Baldursson, Sveinn P. Jakobsson, Sigurður H. Magnússon og Guðmundur Guðjónsson (2006). Náttúrufar og náttúruminjar suðvestan Vatnajökuls. Náttúrufræðistofnun Íslands. Skýrsla NÍ 06008
Tómas Jóhannesson og Jón Gunnar Egilsson, 2009. Hættumat fyrir Vík í Mýrdal. Greinagerð með hættumatskorti. Veðurstofa Íslands. Skýrsla VÍ 2009-008
Þorsteinn Sæmundsson 2000: Berghrun í Seldalssniði í austanverðum Lómagnúp, 7. júní 1998. Náttúrustofa Norðurlands vestra. Greinargerð NNV-2000-004.
Þorvaldur Thoroddsen, 1894. II Ferð um Vestur-Skaptafellssýslu sumarið 1893. Andvari, 1:44-161