Mykines belongs to the eldest part of the Faroe Islands and is formed
for about 60 million years ago.
The Faroese basalt is divided into 3 series of eruption, the lower and eldest,
the middle and the upper and youngest, The lower is formed by eruption through
long fissures of rather fluent lava, which has formed great flat volcanos. In
the sound between Mykines and Mykines Holm, Holmgjogv, one can
see some of the
mightiest on the Faroes, with thickness of about 50 meter.
In between the eruptions there have been shorter and longer periods of
quiscence. There have been so long pauses, that there has formed so much
vegetation, that it now can be seen as thin layers of coal, even in some
places with impressions of conifer (Metasequoia occidentalis). In some places
the layers of coal can be seen in the open, for example with
Valgarsbrugv, under Ketilsheyggi at about 370 meter above sea level. Here it has
been mined in small quantities by inhabitants of Mykines.
At some places on Mykines one can see and easily imagine how the lava as a
fluent mass has has formed the rock. This can for example be seen
at Kumla, in Hellis Gjogv, below the formation "the face of the man" west
of Kumla and on the naked rock on the southern shore of Mykines Holm.
Intermingled with the thin layers of coal there are also layers of tuffclay,
sediments of a reddish colour. It can be seen in the bottom of Lendinger
Gjogv and many places in the steep southern slopes of Mykines. At other
places, as for example on Mykines Holm, one sees layers of clay, basaltic
sandstone, sediments and vulcanic ash.
When lava stiffens, it forms prisms perpendicular to the surfaces of cooling.
In some places, e g at the "Stonewood" above Korkadalur, these are regular
hexagons, in other places more or less regular 4 or 5 sided. The mightier a
layer of basalt is, the slower the cooling proceeds. At the "Stonewood", the
hight of the columns is about 30 meters and as the cooling has been slow,
and the columns are thick. The quicker the cooling, the smaller dimension
of the columns, and the smaller, the more susceptible they are to degradation
by wear and tear of water and freezing.
Holm Gjogv, the sound between Mykines and Mykines Holm is a part of a
dyke. A dyke is a vertical or almost vertical fissure in one or more layers
of basalt, in which younger lava has flown and stiffened. In the dykes the
columns are horizontal and often of small dimensions and are therefore more
susceptible to erosion, often forming a gully or small sounds, grottoes,
tunnels or natural bridges.
The first Gjogv westward from Holmgjogv on the southern side of Mykines
Holm is a dyke under erosion and running parallel with Holmgjogv. The erosion
has gone so far, that there actually is a tunnel straight through the Holm.
It can be verified with a hole on the northern side of the Holm, that the
tidal stream is running in the same direction as in Holmgjogv and by the
fact, that one from a boat can see light shining through.
Where the dyke on the Holm meet the gras slope one can easily see the
thin horizontal placed columns, which form the roof of the tunnel through the
Holm. One can imagine how there in hundreds or thousands of years time will
be two parallel Holmgjovs.
Places of interest on Mykines from a geological point of view.
Mykines Holm.
As mentioned before, one can in Holmgjogv see some of the mightiest layers
of basalt on the Faroes.
The whole Holm is tilted south east, in the westernmost part about 20 degrees,
decreasing to 13 degrees. In the easternmost part of Mykines the tilt is 8
degrees.
The whole Holm is covered by a thick layer of sediments and moraine,
probably having its origin in great slopes north of the Holm, now eroded
by the sea.
Walking on the naked rock on the coast west of Holmgjogv, one sees moraine,
sediments, clay, clay-ironstone and thin layers of coal. The structure of
these layers are so, that one can imagine, that part of them has been formed
as bottom of shallow waters.
At about the middle of the Holm one can close to the southern shoreline see
beautiful formed basalt structures and a little sea and below the crane
and the old ramp, by which the goods for the Lighthouse were brought a
shore, one can see some mighty and beautiful formed basalt structures.
Westernmost one sees the two stacks, Flattidrangur and Pikarsdrangur,
which have great bases, as a sign of lowering of the sea level.
Fjørudalsnev
Fjørudalsnev is the peninsula which is placed between Viðarhelli
and Lendingergjogv and upon which the ramp for the boats and the boat
houses are placed.
On the top there is gras and moraine and the remnants of more nests (boat
houses), which has fallen into the sea for about 50 years ago. South east
there are layers of moraine and clay. At about 20 meter above sea level one
sees brownish clay, clay-ironstone only of a centimeters thickness. Above this
more layers of clay, sand and tuff. At about 20.5 meters altitude there are
very thin layers of coal in which there have been found impressions of
of conifer (Metasequoia occidentalis).
Korkadalur
Korkadalur is placed on the northern side of Mykines and is divides in a
lower and a higher part. In the upper part at the edge of the great plateau
in about 460 meters altitude, one sees the "Stonewood", the about 30 meter
high regularly formed basalt columns.
Kalvadalur
Just south of Biðigjogv one can see a 10 meter thick layer of clay and
coal. Lowest there is brownish clay, higher black clay and several layers of
coal of up to 5 centimeters thickness. This layer can be seen running into the
sea northwards with Tangan i Trøð and on the south coast of Mykines
with Urðarboða. This layer seems to be very widespread on Mykines
and can also be seen in the mountain on the sout side of Mykines and is the
layer from which coal has been broken.
Partly based on: Jóannes Rasmussen: Öldir og Upphav, Emil Thomsen, Tórshavn 1981, together with other written sources