Travel Reference
In-Depth Information
An Explosion Crater: Pocket Basin
Geoscientists have found evidence that Pocket Basin is the crater left from a hydrothermal
explosion (or steam explosion) some 10,000 years ago. As the region warmed, glaciers star-
ted to melt, and a glacial ice dam broke, suddenly lowering the lake level behind it and
reducing pressure below the former lake. The pressure drop caused the hot water in the
underlying rocks to flash into steam, blasting large rock fragments to the surface and leav-
ing a hole. This is called an
explosion crater.
The blasting happened because steam occupies about one thousand times the volume
of the same amount of liquid water. Since the steam could not escape to the atmosphere
fast enough, it created a huge explosion. The result of this violent event was an oval depres-
sion about a mile (1.6 km) across and a large assortment of very active
mud pots.
Sentinel Meadow Trail
goes west just across the bridge near Ojo Caliente Spring. It's
about a 2.2-mile (3.5 km) walk to the Queens Laundry hot spring. On the way are several oth-
er springs and at least eight small
geysers
in the Sentinel Meadow Group of hot springs. Be
aware that the whole area may be too wet for hiking before late July and that the trail provides
no shade.
Sentinel Meadow was named in 1872 for the high
geyserite
mounds or cones that seem to
guard it like sentinels. In the southwest corner of a large marshy area is the very hot spring
called
Queens Laundry.
Here a two-room bathhouse was begun in 1881 by Superintendent
Norris. The bathhouse was never completed, but the ruins are still there, now listed on the
National Register of Historic Places.
Another trail to Sentinel Meadow leaves the former road (now only for walking and bi-
cycling) about a mile (1.6 km) south of the bridge near Ojo Caliente. This trail forks to access
the Fairy Meadows Group of hot springs to the northwest; on the southwest fork are the Fairy
Creek Group, Imperial and Spray Geysers, and Fairy Falls.
Goose and Feather Lakes are slightly farther along the main trail on the left. Goose has
some rainbow and brook trout.
In another mile or so, the main trail to Fairy Falls takes off to the west, described from the
other end at mile 11.3/5.7.
Continuing on the Grand Loop Road 6.0/11.0
“Chief Joseph Story” interpretive sign. The
Nez Perce (pronounced nez-PURS) tribe passed through this part of the park in the summer
