(from the article `Permian Period`) ...the current Roadian Stage and the remainder of the Wordian Stage) in between Murchison`s upper and lower parts of the Permian System was ... Found on http://www.britannica.com/eb/a-z/z/4
Zech'stein` noun [ Greek , from zeche a mine + stein a stone.] (Geol.) The upper division of the Permian (Dyas) of Europe. The prevailing rock is a magnesian limestone. Found on http://www.encyclo.co.uk/webster/Z/2