At one entrance to Redmond Caves, on the east side of Redmond, Oregon. The caves are a lava tube beneath the ground surface and entrances are created when ground above the tube collapses.
<a href="//commons.wikimedia.org/wiki/User:Tequask" title="User:Tequask">Tequask</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>