The landscape of granite
Coarse-grained granite is the kind that is mostly in evidence when you are walking in the Stångehuvud area. Fine examples of coarse-grained granite are visible at the steps when walking on the path between Stångholmesund and Kramkistesund.
In the eastern part of Stångehuvud there is another granite type. This is the more "normal", medium-grained version. In the hillside about 75 metres to the west of Gullmarsvallen there is a sharp delineation between the coarse-grained and the medium-grained granite types. Such a clear distinction between different types of granite is seldom seen in the province of Bohuslän.
At Galleberget, in the north of Stångehuvud, the medium-grained granite type is predominant.
Pegmatite veins crisscross
Typical for the granite landscape in Stångehuvud is that it is crossed by paths of a different rock type, pegmatite. In some places, you can follow these paths for hundreds metres.
Pegmatite can be said to be a granite with very large crystals. The rock was formed in the latter part of the period when the granite magma was solidified. Gradually tensions occured in the rock, resulting in cracks, usually one or a few decimetres wide. To these cracks were drawn water-rich solutions from the ambient, not yet hardened granite, which crystallized slower than the ordinary granite.
The result was pegmatite which has the same mineral composition as granite, but with much larger crystals.
Stonemasons used to call these pegmatite veins "cat" or "cat stripes". These veins were, for obvious reasons, not very popular among the stone workers, because it was not worthwile breaking granite in places with numerous pegmatite veins.
The inland ice has formed the landscape
The pristine parts
of the mountain landscape of Stångehuvud got their present appearance during the last
Like a giant plane, it slid forward and levelled the mountain. When the climate became warmer, numerous tunnels with meltwater were created under the ice in the area of contact with the granite. Under very high pressure and mixed with gravel, stone, blocks etc, the melt water was forced upward and polished the granite.
Read more about the granite:
Some examples of geological formations from the melting of the inland ice:
moutonnées or Sheepbacks
can be seen at
several places in the Stångehuvud area, for example near the
pot holes are found in the slope to
the north of Hästevik. They are about 1,5-2 meters in diameter. They
are easily found, the iron railings around them being visible at distance.
Boulders from far and near
Boulders that have loosened from the surrounding rock surface may be seen at several places in the Stångehuvud area. The only larger beach consisting of naturally formed boulders is found in the northern part of Kramkistesund. Here finer material has surged with the passage of time and rounded boulders have been left behind. Many of these have been transported to Stångehuvud over great distances when the inland ice melted.
Many boulders consist of granite, others of various kinds of veined gneiss, that is to say gneiss where you can distinguish different layers on top of each other. Some gneiss boulders have hints of darker minerals, such as amphibole.
Near Valhall in the western part of Storklyftan there are some impressive boulders of coarse-grained granite which are rather sharply angular. They are seven to eight meters long and have probably broken off from rocks in the surrounding area when the ice was melting.
One interesting boulder that moved to Stångehuvud and that strongly differs from the common bohus granite is divided into two halves, which now lie to either side of a small path, some 50 meters or more to the west of Gullmarsvallen (see photo on the right). For those interested in geologically this boulder is well worth a visit. The boulder is more than one meter high and of a rock type called breccia.