UM geologist describes where the gold comes from

David Alt, author and a retired professor of geology at the University of Montana, explains why gold was found in Grasshopper Creek and the surrounding gulches.

"At Bannack, as in many gold mining districts, much of the production came fast and early from bonanza deposits in stream placers. Early miners working the gravels in the streambed skimmed the cream off the district, leaving the hardest work and leanest pickings for those who came later. That happens because streams concentrate gold as though they were natural sluice boxes. The process is really quite simple.

"When bedrock that contain...