Stratigraphy

The chrono- and lithostratigraphical development demonstrates major events of the area.

The Cambrian succession is dominated by sandstones and siltstones, while Ordovician and Silurian successions are dominated by carbonate facies.

The breaks in the succession reflect changeable conditions until Early Ordovician, not stable enough to maintain continuous marine environment. In late Early Ordovician the stable carbonate platform conditions started to dominate which was to continue to the Late Silurian.

The earliest Devonian was a time of regression in the region. This was the time when a most extensive phase of structuring took place, terminating the Caledonian Orogeny. The uplifted areas were subjected to active erosion, and both Early Devonian and Silurian deposits were removed during this phase.

The area entered into a new stage of deposition during Emsian. Sand-, silt- and claystone were deposited in shallow marine conditions.

During the Late Famennian, the basin areas began diminishing, and by the Early Carboniferous the whole area was once more continental.