By editor
Beaverhead County
In the remote southwestern corner of the state, near the town of Lima, the landscape holds evidence of a different kind of volcanism. The Timber Hill basalt is the remnant of a Hawaiian-style lava flow, a highly fluid river of molten rock that poured across the landscape. Today, the surrounding softer rock has eroded away, leaving the hard basalt standing high as a prominent mesa above Sweetwater Canyon.
Visitor Access
This is a site for viewing rather than collecting. The mesa offers excellent hiking and a stark look at oceanic-style volcanism stranded high in the Northern Rockies. Land ownership in the area is a checkerboard of public and private parcels, so visitors should carry a good land map and verify boundaries before exploring.