There are many rock formations on Mount Erebus. On the northwest upper slope of the active cone near a former exploration camp site, lava flow has formed a prominent outcropping called Nausea Knob, named for the nausea caused by elevation sickness. Also on the northwest slope sits Tarr Nunatak, named by the New Zealand Geographic Board (NZGB) in 2000 after Sgt. L.W. Tarr, an aircraft mechanic with the New Zealand contingent of the Commonwealth Trans-Antarctic Expedition. On the southwest rim of the summit caldera sits Seismic Bluff, named for a seismic station nearby. The Cashman Crags are two rock summits at about high on the west slope of Mount Erebus, southwest of Hoopers Shoulder. It was, at the suggestion of P.R. Kyle, named by the Advisory Committee on Antarctic Names after Katherine V. Cashman, United States Antarctic Research Program team member.