Type locality Kellwasser (Late Devonian) extinction event

The two black anoxic shale layers are referred to as the Lower and Upper Kellwasser Horizon, which suggest two extinction events at a short period of time.

The Upper Kellwasser Horizon marks the Frasnian-Famennian boundary at which 19% of all families and 50% of all genera went extinct (graptolites and cystoids disappeared during this event).

The Lower Kellwasser horizon

This is the official type locality for the Kellwasser (Late Devonian) extinction event