Around 12,000 years ago, Fallon, as well as most of western Nevada, was covered by the giant Lake Lahontan. Rattlesnake Hill, where the "F" overlooks Fallon, was a tiny island in the giant lake.
The water of Lake Lahontan contained a high level of dissolved calcium, and the mechanical action of waves beating against the shoreline created a ring of tufa rocks. The huge "F" is made up of many painted tufa rocks.
Fifteen miles away, at the Salt Caves Cache, which happens to be at the exact same elevation as this cache, you can find more Tufa formations, as well as caves containing prehistoric petroglyphs.
Cajun Team will help watch over this cache.