Three Fingered Jack is a summit of a shield volcano of the Cascade Range in the U.S. state of Oregon. Formed during the Pleistocene epoch, the mountain consists mainly of basaltic andesite lava and was heavily glaciated in the past. While other Oregon volcanoes that were heavily glaciated—such as Mount Washington and Mount Thielsen—display eroded volcanic necks, Three Fingered Jack's present summit is a comparatively narrow ridge of loose tephra supported by a dike only 10 feet (3.0 m) thick on a generally north–south axis. Glaciation exposed radiating dikes and plugs that support this summit. The volcano has long been inactive and is highly eroded.
Southwest side of Three Fingered Jack seen from Pacific Crest Trail
The moraine-dammed lake in summer
A herd of mountain goats seen on the flank of Three Fingered Jack
Three Fingered Jack as seen from Santiam Lake
Mount Washington (Oregon)
Mount Washington is a deeply eroded volcano in the Cascade Range of Oregon. It lies within Deschutes and Linn counties and is surrounded by the Mount Washington Wilderness area.
Mount Washington as seen from Big Lake on the northwest
The spire-like appearance of Mount Washington
The deeply eroded Mount Washington seen from the east
Mount Washington with Belknap Crater on the left
