Archbald Pothole State Park
...that the large pothole in Archbald Pothole State Park in Pennsylvania formed about 13,000 years ago in the Wisconsin glaciation, but was not discovered until 1884 by a coal miner?
...that the large pothole in <b id="mwDg0"><a href="./Archbald_Pothole_State_Park" id="mwDg4" rel="mw:WikiLink" title="Archbald Pothole State Park">Archbald Pothole State Park</a></b> in Pennsylvania formed about 13,000 years ago in the <a href="./Wisconsin_glaciation" id="mwDg8" rel="mw:WikiLink" title="Wisconsin glaciation">Wisconsin glaciation</a>, but was not discovered until 1884 by a coal miner?