RT West Thumb Geyser Basin

Geothermal basin with hot springs and geysers situated directly along a lake's shoreline, creating an unusual juxtaposition of boiling water and cold lake water.

General Information

Pet Policy:

No pets allowed on trails

Seasons:

All year, though heavy snow affects the park between late fall and spring. Some higher elevation trails are snow-free for just a couple of months in mid summer

Rating:

★ 5.0

How to Get There

From Jackson, WY (57 mi): Take US-26/89/191 north through Grand Teton National Park to the South Entrance, then continue on Grand Loop Road to the West Thumb Geyser Basin parking area beside Yellowstone Lake.

Overview

The West Thumb Geyser Basin, including Potts Basin to the north, is the largest geyser basin on the shores of Yellowstone Lake. The heat source of the thermal features in this location is thought to be relatively close to the surface, only 10,000 feet (3,000 m) down. West Thumb is about the same size as another famous volcanic caldera, Crater Lake in Oregon, but much smaller than the great Yellowstone Caldera which last erupted about 640,000 years ago. West Thumb is a caldera within a caldera.

West Thumb was created approximately 162,000 years ago when a magma chamber bulged up under the surface of the earth and subsequently cracked it along ring fracture zones. This in turn released the enclosed magma as lava and caused the surface above the emptied magma chamber to collapse. Water later filled the collapsed area of the caldera, forming an extension of Yellowstone Lake. This created the source of heat and water that feed the West Thumb Geyser Basin today.

The thermal features at West Thumb are not only found on the lake shore, but extend under the surface of the lake as well. Several underwater hydrothermal features were discovered in the early 1990s and can be seen as slick spots or slight bulges in the summer. During the winter, the underwater thermal features are visible as melt holes in the icy surface of the lake. The surrounding ice can reach three feet (one yard) in thickness.

Perhaps the most famous hydrothermal feature at West Thumb is a geyser on the lake shore known as Fishing Cone.

Early visitors would arrive at West Thumb via stagecoach from the Old Faithful area. They had a choice of continuing on the stagecoach or boarding the steamship Zillah to continue the journey by water to Lake Hotel. The boat dock was located near the south end of the geyser basin near Lakeside Spring.

This article uses material from the Wikipedia article "Geothermal areas of Yellowstone", which is released under the Creative Commons Attribution-Share-Alike License 3.0