The old district of Mýrasýsla (also Mýrar ) is located in Iceland . It is located in the west of the country near the city of Borgarnes and has a size of about 3270 km². It is an Icelandic administrative unit .
It includes the beach from Borgarfjörður over the marshland Mýrar to the farm Bruarfoss , ranging from thence to the northeast to the lake Hítarvatn where it makes a bend and extends from there to the east over the pass Brattabrekka to Mount Tröllakirkja on the Holtavörðuheiði over the Arnarvatnsheiði , where the border north of the Úlfsvatn runs to the Fljótsdrög on the northwest side of the Langjökull glacier shield .
In the south, the Borgarfjörður initially forms the border (therefore it initially runs north-east), but then the border follows the Hvíta River to the east and reaches the Langjökull glacier south of the Flosaskarð pass and the Eiríksjökull glacier , which is also the eastern border of Mýrasýsla.
One follows an old settlement pattern: During the time of the land grab, the clan chiefs, as they were used to from Norway, were always able to secure a strip of land that reached into the hinterland from a stretch of coast. This is more or less the area that, according to the land acquisition book, the clan chief Skalla-Grímr Kveldúlfsson secured in the 9th century, who settled the area with his people.
The actual area Mýrar ( Eng. "Swamps") only extends from the sea to a little northeast of Borgarnes. The fact that the administrative unit is sometimes called this, although it is much larger, has historical reasons on the one hand: The court of the district chief was Borg í Mýrum near today's Borgarnes. On the other hand, most of the area is also low-lying wetlands.
The beaches of this stretch of coast, including Borgarfjörður, have always been considered dangerous for navigation, as they are full of reefs and skerries due to the glacial volcanism in the area (see Hafnarfjall , Skarðsheiði ). A famous shipwreck is told in a saga: Böðvar, the son of Egill Skallagrímsson , perishes on the fjord.
Some islands are offshore and were inhabited in earlier times.
Near the sea you will find mainly flat moorland with lakes and ponds as well as many basalt rocks carved by the ice age glacier and other forms of erosion. This moorland was considered difficult to cross in earlier times.
To the east there is moderate mountainous terrain with gently rounded valleys carved by glaciers (Þverádalur, Hvítárdalur etc.). Eventually this passes into the uninhabited highlands with parts of Tvídægra , Arnarvatnsheiði and Hallmundarhraun , where the large glacial shields Eiríksjökull and Langjökull are also located.
The geology of Borgarfjörður is varied.
The former rift zone with active volcanism ran here about 12 million years ago . The area is therefore repeatedly affected by earthquakes and crisscrossed by many crevasses. These also cause geothermal energy to rise and are therefore the reason why the country's largest low-temperature area is located here. Well-known hot springs can be found mainly in Reykholtsdalur ( Deildartunguhver etc.).
A 4 million year old central volcano can be found at Hallarmúli .