A small, shallow exploratory shaft dug by hand to test for the presence of valuable minerals like opal or alluvial gold. Prospectors sink potholes to sample the subsurface gravels or bedrock profile before committing to a larger excavation or mechanical trenching. If a pothole yields good color, the area is usually opened up further.
Heard on the job
We dug a dozen potholes along the creek bed but only found barren gravel.