Banded slate of a distal flysch facies. The light bands within the grey slate represent distal turbidites (Early Carboniferous, Clausthal Kulm Fold Belt, NW Hartz Mountains, Central Germany)
<a href="//commons.wikimedia.org/wiki/User:Gretarsson" title="User:Gretarsson">Gretarsson</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>