Werfen strata

The Werfen strata reach a thickness of about 400m in the Bletterbach. They are a colourful sequence of strata, which reflect the alternation between the advancing and retreating Tethys sea. The basis of the Werfen strata was formed out of Tesero Oolite consisting of small chalk pebbles. This sediment was laid down near the beach in warm seawater, rich in calcium carbonate. Towards the top, the Oolite gives way to chalk, marl and claystone. The sediment structures, such as ripple marks, and cracks from drying out, indicate a shallow area of deposit, that may have been dry at times.
In places the Werfen strata are very rich in fossils. There are various types of mussels and snails, and also marine single cell creatures, such as foraminifer and algae. The upper limit of the formation is the Richthofen Conglomerate, which is only a few metres thick, and is evidence of a period of pushing up and removal.