Browns Bench obsidian

Also called Murphy Hot Springs obsidian, Three Creek obsidian, Cedar Creek obsidian, Browns Bench / Butte Valley Group A

A kind of obsidian

Browns Bench obsidianObsidianRockies & Great Basin

Description

Browns Bench obsidian is named for a ridgeline source on the Browns Bench fault escarpment, between Twin Falls, Idaho, and Jackpot, Nevada. Glass from the same eruption has been found over about 5,500 square kilometers along the Idaho border with Nevada and Utah, from the Cassia Hills to Three Creek. It comes from the Cougar Point Tuff XIII of the Bruneau-Jarbidge eruptive center, which is why it has so many local names. Pebble float turns up near Hollister, Idaho, and south of Jackpot. In Nevada, sites from Elko eastward use mostly Browns Bench glass, and it reaches Pine, Butte and Long valleys. Butte Valley studies of Late Pleistocene and Early Holocene assemblages are cited among its references.

Geology

Obsidian from the Cougar Point Tuff XIII of the Bruneau-Jarbidge eruptive center, a volcanic complex south of the Snake River Plain. It crops out on the Browns Bench escarpment and appears as pebble float over a large area. NWROSL lists many local names, including Murphy Hot Springs, Cedar Creek, Rock Creek, Mahogany Butte, Hudson Ridge and Goose Creek.

Where it comes from

Rockies & Great Basin

States

Quarries and outcrops

Browns Bench escarpment, Twin Falls and Cassia counties, Idaho
West side of Salmon Falls Reservoir
Pebble float to Hollister, Idaho, and south of Jackpot, Nevada
Elko County, Nevada, Butte and Long valleys

Used by

Browns Bench glass occurs in Butte and Long valleys, Nevada (Beck and Jones, cited by Moore); the NWROSL reference sheet lists Beck and Jones studies of Late Pleistocene and Early Holocene Butte Valley assemblages (title only, not read)
Later use in northeastern Nevada from Elko eastward (Moore)

Look-alikes

Stones that are easy to confuse with Browns Bench obsidian.

Other Bruneau-Jarbidge group obsidians such as Coal Banks and Coal Banks Springs (a different glass of the same volcanic complex)

Sources

Pink, Jeremias. 2023. The geology, geochemistry, and geographic distribution of southern Idaho obsidian: A provisional context for archaeological provenance research at the INL CRMO. INL/RPT-23-73575, Idaho National Laboratory.inldigitallibrary.inl.gov (opens in a new tab)
Northwest Research Obsidian Studies Laboratory. Nevada-Idaho-Oregon-Utah Obsidian Sources: Browns Bench (source reference sheet).sourcecatalog.com (opens in a new tab)
Moore, Joe. 2009. Great Basin Tool-Stone Sources: The NDOT Obsidian and Tool-Stone Sourcing Project, 2002 Progress Report. Nevada Department of Transportation, Cultural Resource Section.deschutesmeridian.com (opens in a new tab)

All materials