This hyaloclastite (moberg)
ridge rises 550 m above sea level to the east of the waterfall
Hrauneyjafoss on both sides of River Tungnaa.
Late during the ice age, three explosive sub-glacial fissure
eruptions created the ridge and about 3,000 years ago, lava flows
blocked the few passes through it. Gradually a lake was created to the east and soon its
discharge started spilling over the ridge.
Later, more recent lava flows blocked the discharge and diverted
it to the present location, where it quickly eroded through the ridge
and the lake was emptied. As
a result of the rather quick excavation of the gorge, the material was
carried by the water to create the flat area down to the waterfall
Hrauneyjafoss. The track across the ridge leads to one of the most popular
spots in the interior, Landmannalaugar, about 27 km away.
1973, the construction of the hydroelectric power station at Sigalda
commenced and the work was finished in 1978.
A 925 m long and 40 m high earth dam was constructed just
southeast of the station houses and covered with asphalt to minimize
leakage. Behind the dam a
lake was gradually created. The
access channel from the lake is about 1,060 m long.
At its end, three steel lined pipes, allowing for a drop of 74 m,
supply the hydro power for the generators (50 MW each).
The plans for the power station allow for the addition of one
more generator in the future.
short distance beyond the bridge across River Tungnaa (1968), the
discharge from the power station enters the river.
In the channel and the gorge is a layer of pillow lava, which is
usually created in water under great pressure during submarine or
sub-glacial eruptions. The
road from the bridge continues north on the eastern and newer route over
the Sprengisandur track all the way to the northern part of the country.
After the construction of the so-called Hrauneyjar hydroelectric
power station, an easier and shorter route connects with this route just
north of the Sigalda ridge.