The Marmes Rockshelter (also known as (45-FR-50)) is an archaeological site first excavated in 1962,[3] near Lyons Ferry Park and the confluence of the Snake and Palouse Rivers, in Franklin County, southeastern Washington.

[6] Excavations at the site were started by Daugherty and Roald Fryxell, a geologist, under the auspices of Washington State University (WSU) and the National Park Service in 1962, and continued until 1964.

[3][7] In 1965, Fryxell returned to the site along with Professor Carl Gustafson and students from WSU,[8] and had Roland Marmes dig a trench in front of the rockshelter with his bulldozer, which turned up human and elk bones.

Within three days of the closure of the Lower Monumental Dam in February 1969, the site was completely underwater, due to the seepage of water through thick layers of gravel that had not been accounted for.

[18] In layers dated to 7,000 years ago, a large number of shells belonging to a snail of the genus Olivella were found, which would have been imported from the West Coast of the United States, 200 miles (322 km) away.

[18] In addition, one of the five known Jefferson Peace Medals was found associated with the most recent human remains at the site, evidently having been given to a local Native American leader (presumably of the Nez Perce) during the Lewis and Clark Expedition.