Situated in the Ódáðahraun lava field

Lava plain

A lava plain, also called a lava field or lava bed, is a large expanse of nearly flat-lying lava flows. Such features are generally composed of highly-fluid basalt lava, and can extend for tens or even hundreds of miles across the underlying terrain...

, Trölladyngja is the biggest of the Iceland

Iceland

Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...

ic shield volcano

Shield volcano

A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...

es, reaching a height of 1468 metres (4,816 ft) above sea level

Sea level

Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...

, and rising almost 600 metres above the surrounding desert

Desert

A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...

 and lava fields.

It is about 10 kilometres in diameter and its inclination is 4 to 5° in the lower slopes, but 6 to 8° at higher elevations. Its oblong crater is about 1,200 to 1,500 metres in length, 500 metres broad, and about 100 metres deep.

Most of its lava

Lava

Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

 fields have flowed in a northerly direction, with one branch of it reaching the valley of Bárðardalur, a distance of roughly 100 km.