I came upon the hole pictured in the photos while hiking on a fire road in Mendocino county, (California) a few days ago. Hole was about 1.5 inches (4 cm) in diameter, and lined with a filmy white material which is pictured peeled away in the second photo. I probed the hole with a stick, and it was deeper than one foot. Any idea what made this?  Ben

To follow this topic, click here.