ABSTRACT This guide presents an eight-hour, in-person tour of intersecting geologic and human history in western Nevada, USA. A 25 megaton phreatomagmatic blast created a mile-wide (1.6-km-wide) maar, now filled by Soda Lake. The magnitude 7 Dixie Valley earthquake ripped along more than 45 km of the Stillwater Range front in 1954. The 12 kiloton Shoal nuclear test in 1963 created a 50-m-wide cavity in solid granite. This field trip generally follows the GSA guide published in GSA Field Guide 61 (available at https://pubs.geoscienceworld.org/gsa): Louie, J.N., and Ruprecht, P., 2021, The blast, the quake, and the bomb: A guide to high-energy events in western Nevada, USA, in Florsheim, J., Koeberl, C., McKay, M.P., and Riggs, N., eds., Field Excursions from the 2021 GSA Section Meetings: Geological Society of America Field Guide 61, p. 201–219, https://doi.org/10.1130/2021.0061(09) .

ABSTRACT This guide presents an eight-hour, in-person tour of intersecting geologic and human history in western Nevada, USA. A 25 megaton phreatomagmatic blast created a mile-wide (1.6-km-wide) maar, now filled by Soda Lake. The magnitude 7 Dixie Valley earthquake ripped along more than 45 km of the Stillwater Range front in 1954. The 12 kiloton Shoal nuclear test in 1963 created a 50-m-wide cavity in solid granite.

Abstract Interstate 80 between Elko and Carlin, Nevada, follows the valley of the Humboldt River. The Humboldt drains a 17,000 square mile basin along its 275 mile course, located entirely within the State of Nevada. While barely a trickle of water in late summer, spring floods may swell the river well over its banks. The average annual discharge is 256,000 acre-feet, although this varies from 25,000 acre-feet to 635,000 acre-feet annually. The Humboldt River played an important part in the history of the American West during the early years of westward settlement. In 1928, Peter Skene Ogden led a party of Hudson’s Bay Company trappers south from Idaho, following the Humboldt to the present location of Winnemucca. Ogden trapped there briefly, returning to Utah for the winter. The following spring, he returned to follow the Humboldt to the marshes west beyond the Stillwater Range, where the Humboldt spreads and disappears into the desert sand. For ten years, British and American trappers worked the river, then called Mary’s River. By 1838, the beaver were largely trapped out, the market for beaver felt hats was waning, and the American west was about to change. Three years later, the first party of immigrants to California, on the advice of mountain men, followed the Humboldt west from near its source to the Humboldt Sink, then crossed the Forty-Mile Desert to reach the Carson River and the Sierra Nevada. In 1845, John C. Fremont began his explorations and publicized the desert country and the Humboldt Trail.

Abstract Interstate 80 between Elko and Carlin, Nevada, follows the valley of the Humboldt River. The Humboldt drains a 17,000 square mile basin along its 275 mile course, located entirely within the State of Nevada. While barely a trickle of water in late summer, spring floods may swell the river well over its banks. The average annual discharge is 256,000 acre-feet, although this varies from 25,000 acre-feet to 635,000 acre-feet annually. The Humboldt River played an important part in the history of the American West during the early years of westward settlement. In 1928, Peter Skene Ogden led a party of Hudson’s Bay Company trappers south from Idaho, following the Humboldt to the present location of Winnemucca. Ogden trapped there briefly, returning to Utah for the winter. The following spring, he returned to follow the Humboldt to the marshes west beyond the Stillwater Range, where the Humboldt spreads and disappears into the desert sand. For ten years, British and American trappers worked the river, then called Mary’s River. By 1838, the beaver were largely trapped out, the market for beaver felt hats was waning, and the American west was about to change. Three years later, the first party of immigrants to California, on the advice of mountain men, followed the Humboldt west from near its source to the Humboldt Sink, then crossed the Forty-Mile Desert to reach the Carson River and the Sierra Nevada. In 1845, John C. Fremont began his explorations and publicized the desert country and the Humboldt Trail.

Abstract On December 16, 1954, two large-magnitude earthquakes occurred nearly simultaneously in the Fairview Peak-Dixie Valley area of western Nevada (Fig.1) (Slemmons, 1984). The first earthquake (Ms = 7.25) was centered near the middle of the Fairview Peak fault zone, where it crosses U.S. 50. It was followed four minutes later by a second shock(Ms=7-)centered on the east flank of the Stillwater Range in the northwest part of Dixie Valley, about 37 mi (60 km) to the north. Both earthquakes were accompanied by extensive and spectacular surface faulting (Slemmons, 1957). The combined rupture zone is about 62 mi (100 km) long and 18 mi (30 km) wide. The most spectacular scarps of this zone are at the main site (Figs.2 and 3) on the southeast side of Fairview Peak, an area that is about 5.5 mi (9 km) south of U.S. 50 and is accessible by passenger car on a new graded road.