Reykjavík Grapevine - 07.06.2013, Side 40

Where Are The Glowing Rocks?
…I came to Iceland to see volcanoes!
40The Reykjavík Grapevine Issue 7 — 2013
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As you would expect, many visitors to Iceland are more
than eager to view the country’s famous volcanoes. They
may, however, be surprised to discover little more than
rugged, cold lava flows and non-smoking volcanoes.
These are of course fine sights, but they’re not the glowing
lava and fuming craters that many expect from one of the
most active volcanic regions of the world. The explanation
is rather simple: One needs to happen upon a live magma-
spouting event to see those spectacular sights, and those
occur roughly once every three to four years.
Iceland is born
Iceland formed gradually over many years after the Mid-
Atlantic Ridge became positioned close to, and later over,
one of the world’s more powerful mantle magma plumes,
one of its so-called hot spots.
Magma production within the plume and rising molten
rock beneath the otherwise submarine ridge was sufficient
to build up an approximately 40 km thick crustal expanse
of basalt covering an area of 200,000 km2. Out of all that,
an area of 103,000 km2 rose above sea level to form an is-
land—Iceland. The oldest rocks above sea level, which are
found east and west of the presently active volcanic zones,
are about 15 million years old.
The plates drift apart approximately 2.5 cm per year,
but in reality the spreading is localised and a long time
passes between periods of rifting in any particular area. In
each rifting episode, the plates "jump" apart in particular
regions, with the associated earthquakes and new fracture
formation—or movement along existing faults. This hap-
pens mostly without any magma surfacing, but from time
to time the Earth mends itself and one of the volcanoes
blows the lid or a new volcanic fissure opens up.
The systems
During the past 1,200 years or so, over 250 eruptions are
known to have occurred. In terms of weight, the magma
extruded at the surface on land over the past 11,000 years
(the Holocene period) totals at about 1,500 billion tonnes.
A still larger mass has simultaneously solidified in the
crust, beneath the surface, at a considerable depth.
The active volcanic zone covers an area of around
25,000 km2, which equals to about one-fourth of Iceland’s
surface. In this zone, volcanoes and volcanic fissures
do not appear at random, but are rather confined within
elongated areas bounded by fissures, faults and volcanic
formations. These areas, called volcanic systems, are typi-
cally 5-20 km wide and 20-100 km long.
There are 30 distinct volcanic systems in Iceland.
Three are located on the Snæfellsnes Peninsula, four on
the Reykjanes Peninsula, six in South Iceland and four in
Northeast Iceland. The remaining fourteen dot the Central
Highlands.
Most volcanic systems support a centre of volcanic
activity, usually either a high composite cone or a large
mountain massif with a central area of subsidence (a
caldera). Underneath the majority of these centres, com-
monly referred to as central volcanoes, a magma chamber
lurks somewhere in the abysses of the earth.
Although volcanic activity is most frequent at this cen-
tre, eruptive fissures also stretch out in opposite directions
from the centre and open up from time to time. Large faults
or open fissures without any traces of volcanic activity cut
through the landscape like multiple steps or gaping cracks.
Eruptive fissures are distinguishable by the presence of
crater hills or pits aligned in a row, commonly composed
of a number of segments. Some are up to 20-30 km long,
but they typically measure 0.5 to 5 km in length.
Birthmarks
Iceland’s most geologically active areas are rifting zones
that stretch roughly from SW to NE across the island. Ad-
ditionally, there are three lateral eruptive zones on the
Snæfellsnes Peninsula in South Iceland between Öræfa-
jökull and Snæfell.
Within the rifting zones, fracture magma fountain erup-
tions—typical of basaltic sea-floor volcanism—are com-
mon, with large, central volcanoes also occurring from
time to time. In the lateral volcanic zones, however, erup-
tions tend to be more explosive in nature, with magma ex-
truding through high volcanoes and fractures (more akin
to the activity in continental volcanoes).
Evidence of these eruptions manifests itself in a vari-
ety of structures: crater rows with spatter cones, scoria
and pumice craters in offset sections, rows of explosion
craters, lava shields, large mountain ranges with calderas,
high cones (stratovolcanoes), volcanic domes and large,
circular tephra craters.
Eruptions below the ocean or icecaps are also not un-
common. These lead to ash-producing eruptions and the
sub-glacial ones can produce swift melt-water floods,
termed ‘jökulhlaups.’
So, what is there to say about the active volcanoes? If
you’ve timed your visit right and a volcano happens to be
erupting, you can probably go check it out. However, do
be careful and follow the rules and directives set by ‘Al-
mannavarnir’ (“Icelandic Civil Protection System,” www.
almannavarnir.is). If no volcanoes are erupting, there’s still
plenty to see.
Halfway between Reykjavík and Styk-
kishólmur in the west is a great hike
to the rim of Eldborg (“Fire City”). Al-
though it’s not quite a proper mountain
at 112 metres above sea level, Eldborg
is still well worth a visit. It is a circular
crater formed out of dark and reddish
basalt lava spatter and some scoria
that looks like a circular wall surround-
ing a deep pit. From afar, it really looks
like an exceptionally well-formed vol-
canic crater. It is 5-8,000 years old, the
product of a vigorous but short-lived
lava eruption on a short fissure.
How to get there:
The hike starts not far from a farm
called Snorrastaðir in Hnappadalur
valley, off Snæfellsnesvegur (Road 54).
On the road connecting Snorrastaðir
to the main road, cross a bridge over
the small river Kaldá. Head more or
less straight for the crater, through
birch shrubs and willows or moss and
grass-covered lava. The scoria base of
Eldborg and its high lava wall are cut by
the trail, so the route up there is easily
discernible.
While hikers can walk along the cra-
ter’s rim, they should refrain from do-
ing so in order to preserve this unique
but fragile formation. The crater is
about 200 metres wide and 50 metres
deep. After marvelling at the surround-
ings, head back the way you came
from. Note: Eldborg is protected by law
as a natural monument—do not walk
off the path or leave anything behind.
Time:
The hike should take about two hours
total.
Distance:
The distance covered is about six ki-
lometres.
An unobtrusive mountain south of the
Hellisheiði Geothermal Power Plant,
Stóri-Meitill (514 metres above sea
level), doesn’t appear to hold much ap-
peal for the hiker at first glance. Looks
can, however, be deceiving. Hiking to
the summit not only provides a great
view over south Iceland—including
Hekla, Eyjafjallajökull and Vestman-
naeyjar—but it also reveals a large,
deep volcanic crater. The eruption that
created Stóri-Meitill (“The Large Chis-
el”) likely occurred under a rather thin
glacier on a short fissure, blowing ash
and pumice (tephra) into the air. Mean-
while, less active craters formed the
hills to the southwest of Stóri-Meitill.
How to get there:
From Road 1, take Þrengslavegur
(Road 39), a low pass between the
bulky mountain Lambafell and the
cone-shaped Stakihnúkur. It branches
off from Road 1 at an area of lava field
called Svínahraunsbruni, which dates
to the year 1000. You may find a suit-
able parking place at the intersection
between Þrengslavegur and a short
road leading to a mine.
Cross the main road and a small
lava field in the direction of Stakih-
núkur. Climb the screes of the peak di-
rectly to the top (15-20 min.). Descend
a bit and start turning to your right,
across grassy and mossy hillocks and
gravel flats towards the north-western
shoulder of Stóri-Meitill.
Pass the highest cliffs on your right
and hike upslope along the southwest
(right) side of the tuff rocks. The slope
is steep and a low-angled, and the
rocky section at the top requires some
very light scrambling. Pass the cairn
at the flat top to marvel at the big vol-
canic crater. The best descent route
follows the SW-ridge of Stóri-Meitill
for about a kilometre. Head down
and walk back towards the NW shoul-
der. From there, head for Stakihnúkur
again but instead of climbing it, hike
down the small valley at its southern
side and back to your vehicle.
Time:
The ascent should take about 1.5–2
hours.
Distance:
The length of the hike is about 5 ki-
lometres.
Ari Trausti Guðmundsson is a trained geo-
physicist and mountaineer who has written
a number of books from short stories and
poetry to fiction. His most recent English lan-
guage books are ‘Focus on Iceland,’ a road
guide for tourists, ‘Magma,’ a book documenting Icelandic
volcanoes from the Katla eruption in 1918 to Vatnajökull in
2011, and ‘Summit – 100 Mountain Hikes’.
Hik
ing
Volc
ano
sFor
Eldborg:
The perfect
crater
Stóri-Meitill:
A large chisel
Travel
Fun trivia question answer: A) Caraway seeds
(Please not that "delicious taste" is a relative
term. Results may vary.)