Detailed information up to plate 12 at the Alpilakopf

The geology hiking trail follows the boundary of the Alpiner Muschelkalk to the younger Partnach Formation. The boundary can be easily seen in the field. While there are trees growing on the carbonates, the trees on the marls and clay stones of the Partnach formation were chopped down to make way for meadows. Plate 8 and plate 18 west of the Torasee are located on the dark clay stones and marls of the Partnach formation. These rocks were deposited in a 100 metre deep marine basin. Several calcareous layers indicate better marine conditions during some periods. However, there were mostly rather poor living conditions similar to the conditions in parts of the Black Sea today. The Partnach formation is overlain by the carbonaceous rocks of the Arlberg Formation – plate 9 and plate 17. At plate 9 you can take a shortcut which takes you directly to plates 20 and 21, at the Fritzensee.
The layers of the rock of the Arlberg formation form the chains of Klostertal-Arlberg. They consist of carbonates and dolomites with some intercalated clay stone, marl and reywacke layers that were deposited in a tropical shallow marine sea. Sometimes explosive growth of silica algae occurred at the time of deposition, resulting in siliceous layers in the carbonates. Some layers of the Arlberg formation contain a large number of fossils.

In a shallow depression further up, you will find plate 10 explaining the Raibl formation. The Raibl formation consists of very different rocks like dark sandstones, marls, greywacke and gypsum. These sediments indicate their deposition in a very shallow, partly tropical sea that enabled the precipitation of large bodies of gypsum when such shallow seas were sometimes cut off from the open sea and then evaporated.  In some layers fossils like pollen, leaves, shells and fish teeth can be found.

The last hike up to the Wannaköpfle traces the next younger formation – the Hauptdolomite. The Hauptdolomite – described on plate 11 and also on plate 15 north of Falla- builds up the steep walls of the Vandanser Steinwand, Davenna and the peak regions of the Klostertaler Alps. The peaks of Itonskopf and Schwarzhorn also consist of Hauptdolomite. Deposition of the Hauptdolomite took place in a very shallow sea which went dry at low tide – a situation similar to the present day Bahamas or the Persian Gulf. Small grains of dolomite were deposited and immediately overgrown by thin layers of algae. In the upper most parts of the Hauptdolomite – the so called Plattenkalk – large oyster shells can be found.
Walking up to plate 11, you have crossed about 100 million years of the Earth’s history from the uppermost Carboniferous to the uppermost Triassic period. If you got the impression that all kinds of rock seem to be more or less the same, you’re right. Even geologists have trouble discerning which formation a single rock is from. Normally, the age and the type of the formation can only be ascertained by its fossils and/or the sedimentary sequence of different rocks. For example, the Raibl formation is typically indicated by greywacke, sandstones and large bodies of gypsum, whilethe Muschelkalk formation is indicated by thick bedded carbonates with thin intercalated clay layers.

Don’t forget to take a look at the sink holes when crossing eastwards to the peak of Alpilakopf. They are the result of gypsum dissolution in the underground  and mass movements.

At the foot of the Itonskopf, which stands out like a tooth, the typical Hauptdolomite debris is deposited as a mound. Please do not try to climb to the peak of the Itonskopf unless you are an experienced climber and you do not suffer from vertigo.

The trail from Itonskopf towards Alpilakopf follows a double ridge, which was caused by the splitting of the mountain body in the direction of the cleft.