The "Taconic Unconformity" near Catskill, NY.  This <a href="https://en.wikipedia.org/wiki/Unconformity#Angular_unconformity" class="extiw" title="w:Unconformity">angular unconformity</a> separates the the Austin Glen Formation (<a href="https://en.wikipedia.org/wiki/Ordovician" class="extiw" title="w:Ordovician">Ordovician</a>) from the overlying Rondout Formation (<a href="https://en.wikipedia.org/wiki/Silurian" class="extiw" title="w:Silurian">Silurian</a>) and Manlius Formation (<a href="https://en.wikipedia.org/wiki/Devonian" class="extiw" title="w:Devonian">Devonian</a>).
<a href="//commons.wikimedia.org/wiki/User:Rygel,_M.C." title="User:Rygel, M.C.">Michael C. Rygel</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>