Zechstein

Though situated at the time near the equator (where high temperatures and arid conditions facilitated evaporation), the sea's inception likely stemmed from a marine transgression rooted in a phase of de-glaciation; the southern portion of Pangaea, the former (and future) Gondwanaland, supported ice sheets in the early Permian.

The eventual disappearance of the Zechstein Sea was part of a general marine regression that preceded and accompanied the Permian-Triassic extinction.

Just above the base of the Zechstein formation is a fairly thin layer of shale, or slate, where it has been metamorphized, known as the kupferschiefer for its high copper content.

In its unmodified form, this layer is high in sulfur compounds that are typical of silt deposited in stagnant shallow marshland.

From the Middle Ages into the modern era, this thin but widely dispersed constellation of ore bodies has been of immense importance as a source of copper across much of northern Europe.