Wilson Butte Cave

Useful Information

Location: On the Snake River plain near Twin Falls in Jerome County.
Open: No restrictions.
Not accessible in winter.
Fee: free.
Classification: SpeleologyBlister cave
Light: bring torch
Guided tours:
Bibliography: Ruth Gruhn (1961): The archaeology of Wilson Butte Cave, south-central Idaho, Occasional papers of the Idaho State College Museum #6, Idaho State College; Paperback, 202 pages
Ruth Gruhn (2006): New excavations at Wilson Butte Cave, South-Central Idaho , Occasional papers of the Idaho State College Museum #38, Idaho State College; Paperback, 290 pages
Address: Twin Falls Bureau of Land Management, 2536 Kimberly Road, Twin Falls, ID 83301, Tel: +1-208-732-7200
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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21-NOV-1974 added to the National Register of Historic Places (NRHP).
1959 archaeological excavation.
1988 archaeological excavation.


Wilson Butte Cave is an important archaeological site and an extraordinary geotope. Located near Twin Falls on the Snake River Plain, the cave is of volcanic origin. The wide flat bow-shaped depression is formed by volcanic rocks, ancient lava flows which erupted about 11Ma ago. The plain is actually the track of the Yellowstone hotspot, the Yellowstone Park is located at the eastern end of the plain. North of Twin Falls lies a group of hills, the harder parts of the lava, which contain a cave which is actually a single huge domed chamber. The archaeological importance of the site overshadows the geologic uniqueness of this blister cave.

This cave was inhabited by man probably since 16,000 years. At this time the climate was much cooler and wetter than today, it was at the end of the last ice age. The cave provides some of the earliest evidence of human presence in Idaho and North America. The archaeologist Ruth Gruhn interprets some of the material she excavated to be this old, but the age is not based on any physical dating. Other archaeologists prefer a more conservative age of 10,000 years BP.

The cave was occupied by the Fremont People, an old culture which existed before the Shoshone culture. The existence of this culture was proposed by B. Robert Butler, University of Utah, in 1980. Ruth Gruhn's 1989 excavation at Wilson Butte Cave supported this theory. The Freemont culture is defined by their basketry, pottery, clay figurines, pictographs, and petroglyphs.

The cave is maintained by the Bureau of Land Management (BLM), who allow access during most of the year. Only during winter the cave is not accessible, actually because of bad road conditions. However, the site is a National Heritage and protected by law, and vandalism would most likely change the accessibility, the cave would be closed. We want to cite a few points from the ethic code of the BLM: Treat rock art, historic structures, and archaeological features with respect. Touching, chalking, or making rubbings or latex molds cause damage to rock art, gravestones, and fossil trackways. Take photographs or make a sketch instead. Report looting and vandalism to a BLM ranger or other local authority.