Table Mountain is the long, flat-topped ridge that dominates the horizon north of Jamestown — an 18-mile lava flow that filled an ancient river channel about ten million years ago. The harder volcanic rock has resisted erosion while the softer terrain around it has worn away, leaving the river upside-down in the landscape: the old streambed now sits on top of the mesa.
In spring, the grasslands on top explode with wildflowers — goldfields, lupine, owl's clover — and the BLM keeps a few short trails open along the northern flank. It is one of the best easy hikes in the Mother Lode for the geology alone. Access is from Shell Road or Rawhide Road north of town; aim for a March or April morning before the heat sets in.