Volcanic activity on the peninsula still exists in this Flank Zone extending westward from the Icelandic Graben, and modern science suggests one eruption there during historical times. The Book of Settlements mentions this eruption and explains its beginning in a legendary manner, which is not commonly acceptable nowadays. It applies to the cinder crater Eldborg, which is now considered older than 5000 years. The westernmost volcanic area of the peninsula is named after the Snaefell’s Glacier and has an area of about 600 km². Further east is the Lysuskard System (150 km²), and still further east the Ljosufjoll System (1,800 km²). The first probably has been active 20-30 times during Holocene, the second one twice, and the third more than 20 times. Still further east is the Snjofjoll System, which has been dormant from the latter part of the Ice Age to this date.
The Snaefell’s Glacier is in the centre of the westernmost system. It covers a cone shaped volcano, which has been dormant for more than 1,750 years and around it are several lava fields and small, symmetrical craters created during Holocene. Some of the lavas flowed into the sea and fortified the coastline against the constant beating of the brakers. The Snaefell’s Glacier’s eruptions were both explosive and effusive. The main crater is about 200 m deep, filled with ice and surrounded by a precipitous wall of ice.
The most prominent signs of the volcanic activity within this system during Holocene are the 5,000-8,000 years old crater Budaklettur furthest east, the Hnausa Lava Field in the southern slopes of the Jokulhals Pass (<1,750 years old), the Klif Lava Field (same area and age), the Hellnar and Kalfatradir Lava Fields (<1,750 years old), the Haa Lava Field (Mt Snaefell; 1,750 years old), the Saxholar Lava Field, the Prestar Lava Field (Raudholar), the Vaera Lava Field (Sjonarholl; <1,750 years old) and the Nes Lava Field (Ondverdanesholar). Older signs of volcanic activity are found in several places, such as the crater plugs Londrangar, craters Purkholar, Holaholar, which were created off the coast and connected during later eruptions, and crater Bardarlaug (>10,000 years old).
The Lysuskard system covers the central area of the peninsula. It depicts volcanic activity during the Ice Age and interglacial lava fields. Only two lava fields, Hraunsmulahraun and Blafeldarhraun, were created during Holocene. They are very prominent in the southern slopes of the mountain range, where the lava cascaded down to the ocean from craters on top of the mountains. The fissures of this system extend between Mt Trollatindar and the headland Bulandshofdi on the northern side of the peninsula.
The Ljosufjoll System derives its name from a short and light coloured rhyolite mountain range to the south of the town Stykkisholmur. The largest eruptions during Holocene took place in the valleys Hitardalur and Hnappadalur. This system extends between the Kolgrafafiord Bay and the valley Nordurardalur. Its most prominent craters created the lava fields Berserkjahraun, Svelgsarhraun, Horgsholtshraun, Tunun, Langadalshraun, Raudamelshraun, Gullborgarhraun, Barnaborgahraun, Raudhalsahraun, Eldborgarhraun, Holmshraun, Hagahraun, Raudkuluhraun, Hraundalshraun and Grabrokarhraun. Little is known about the age of most of the lava fields and quite a few lava caves, both hidden and discovered, were created at the times of the eruptions. The craters Raudamelskulur are estimated to be 2,600 years old.
The Grabrok Lava Field counts among the most rugged AA lava fields of the country. It was created by a fissure eruption 3,600-4,000 years ago, which left three craters behind. The lava field is covered by fringe moss and bushes (birch, willow). The craters were declared inviolate in 1962 after considerable damages by quarrying.
Photo Credit: Anjali Kiggal