Rock covered trail surface on the Ole Ranger Trail at Patapsco Valley State Park. Illustrative of the surface=rock property on OpenStreetMap
<a href="//commons.wikimedia.org/wiki/User:Eplack" title="User:Eplack">Elliott R. Plack</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>