Nature and geology

Geology

The bedrock of the Fjallabak Reservation (Friðland að Fjallabaki) was formed on the western rift zone of the North American tectonic plate, approx. 8–10 million years ago. Volcanic activity resumed in the area approx. two million years ago when the eastern rift zone moved south. The reason for the volcanic activity in the area is that hot, alkaline magma from the rift zone north of it squeezes south, melts the earth’s crust and mixes with it in various ratios. This type of mixed rock can be found in i.a. Laugarhraun, Námshraun, Dómadalshraun and Hrafntinnuhraun.

Volcanic activity was high in the area during the most recent ice age, such as when the tuff mountains Löðmundur and Mógilshöfðar and the rhyolite mountains Bláhnúkur, Brennisteinsalda and Kirkjufell were formed. Rhyolite lava from the last warm period of the ice age can be found under North Barmur and in Brandsgil. In present day (the last 10 thousand years), all volcanic activity has been confined to a belt that lies SW-NE over the nature reserve from Laufafell to Veiðivötn.

Torfajökull Area

The Fjallabak Nature Reserve covers part of the Torfajökull area, the most extensive rhyolite area in the country. Rhyolite magma is dense and cold and forms thick lava fields that are small in size. Upon rapid cooling, the magma forms black, glossy glass, known as obsidian, but otherwise, rhyolite is usually grey, yellow, pink or green in colour. This varied colour palette is mostly due to geothermal transformation; the Torfajökull area is one of the biggest geothermal areas in the country, as evidenced by the many pools and hot springs there.

The Torfajökull area is an active central volcano and is characterized by a large oval caldera. The rim of the caldera lies through Háalda, Suðurnám, North Barmur, Torfajökull, Kaldaklofsjökull and Ljósártungur. There are significant monuments found in the Torfajökull area, such as rhyolite mesas and rare geothermal phenomena. Volcanic activity and active erosive agents, such as glaciers and glacial rivers, have shaped the area, and the landscape is characterised by craters, lava fields, canyons and light-coloured sandbars.

Early in the last glacial period, approx. 57,000 years ago, a large series of eruptions formed many rhyolite mountains on the edges of the caldera. Most of the highest rhyolite mountains in the area belong to that series, including Laufafell, Kirkjufell and Rauðufossafjöll, rhyolite mesas formed in a sub-glacial eruption and are unique both to Iceland and the world.

Since the last ice age, there have been 11 eruptions in the Törfajökull area, all in the western and north-western part. Simultaneous eruptions in the Bárðarbunga system and Torfajökull have occurred at least six times, thereof twice since the settlement. These are the Vatnaalda eruption in 871 that formed the instantly recognisable and wide-spread ash layer (the Settlement Layer) and the Veiðivötn eruption in 1477.

Geothermal Power

The Torfajökull geothermal area is very large, approx. 15 km long from west to east and approx. 12 km wide at its widest. Surface geothermal energy is very diverse, and rare geothermal phenomena are found there. The main characteristics of the geothermal energy in the area are the so-called mudpots, shallow hot springs with almost clear water with boiling mud at the bottom. Mud hot springs, muddy hot springs, geysers, fumaroles and extensive alterations are also common. Carbon dioxide springs and pools are found on the edge of the high-temperature area in runoff areas.

Vegetation and Habitats

Because of the nature reserve’s cold climate, the growth period for plants is barely two months a year and soil formation is extremely slow. The soil lacks humus and weathered materials. As a result, it is coarse and loose and easily transported by wind or water. Sand drift is copious in the area, and during volcanic eruptions, large parts of it are smothered in lava and ash. With all these factors in mind, as well as the fact that Landmannaréttur has been a grazing area for centuries, the lack of vegetation in the natural reserve does not come as a surprise. Areas with continuous vegetation are small, and the largest and most lush areas are close to rivers and lakes, e.g. the Kýlingar area, a near continuous bay with pools and ponds and various wetland plants. The acidic rhyolite bedrock is barren in large areas, but the tuff mountains, however, are often overgrown with bright green R. lanuginosum moss.

The Torfajökull caldera contains a diverse selection of higher plants, as almost two hundred higher plant varieties have been discovered there. A few rare varieties of vascular plants are found in the area, mainly around the hot spring areas. Moss is a distinctive feature of the landscape, and in some places, there are continuous moss spreads.

The nature reserve contains habitats with a high conservation value, as well as habitats that are rare to Iceland and must be especially protected. These include the habitats of mythical hot springs, starling swamp habitats, willow shrubs, wetland hot springs, species-rich coronary algae lakes, geothermal streams, muddy hot springs and mountain hot springs.

Limnology

The lakes in the Fjallabak Nature Reserve are cold mountain lakes. Aside from the plants, they are inhabited by various microscopic organisms and trout. Brown trout has run up from Tungnaá to Kýlingar and Kirkjufellsvatn. Brown trout has also been found in Ljótipollur and Frostastaðavatn for as long as anyone can remember. Arctic char was first released in lakes around the area around 1970 and has multiplied so rapidly that most lakes in the nature reserve now have a multitude of small, non-harvestable trout that cannot grow due to lack of food. Organized net fishing began in the lakes in 1981 in order to reduce the trout stock so it would be more in accordance with the primary productivity of the lakes.

Wildlife

Birdlife is sparse, like elsewhere in the highlands, but there are 23 known species of nesting birds found in the nature reserve. Snow buntings are the most common, but great northern loons, red-throated loons, swans and red-necked phalaropes can be spotted around the lakes. Harlequin ducks are occasionally spotted in Jökulgilskvísl and in Landmannalaugar and have been known to nest in the area.

Arctic foxes are rarely spotted in the nature reserve. Mink can be found in the nature reserve and are thought to have first arrived there around 1950.

Around 90 species of small animals have been recorded in Landmannalaugar. Of these, three are dependent on geothermal energy: Pirata piraticus, Scatella tenuicosta f. thermarum and an unnamed dipterous muscidae.