McLaughlin Canyon, Okanogan County

Tonasket Gneiss and the Metamorphic Core Complex

The canyon walls are Tonasket Gneiss, a high-grade metamorphic rock that is part of the Okanogan Metamorphic Core Complex. During Eocene extensional collapse about 48 to 51 million years ago, deep-crustal rock was exhumed as overlying rock slid westward. What visitors see today are cliff faces of coarse-grained, banded gneiss with quartz-feldspar light layers and biotite dark layers. This is not the Columbia River Basalt that dominates the plateau to the south. McLaughlin Canyon (also spelled McLoughlin Canyon) exposes rock that is far older and structurally distinct.

The southwestern slope of Tonasket Mountain contains over 1,000 feet of interconnected fracture caves and crevasses. These are mechanical fracture caves in gneiss, not limestone solution caves. Some passages are naturally lit through narrow overhead slits reaching 20 to 40 feet high. Others require artificial light and short rappels to access deeper chambers.

The 1858 McLoughlin Ambush

On July 29, 1858, warriors from the Chelan, Okanogan, and Columbia tribes ambushed a party of approximately 160 miners, traders, and packers traveling north toward the Fraser River gold fields in British Columbia. The party was led by David McLoughlin, son of Dr. John McLoughlin, former Chief Factor of the Hudson's Bay Company's Columbia District. This was the only armed conflict between settlers and indigenous peoples in Okanogan County. Firing continued for several hours near the mouth of the canyon before the caravan retreated to the Okanogan River. A historical marker erected by the Okanogan County Historical Society stands at the site today.

The canyon trail follows the original Hudson's Bay Company Brigade Trail, a fur trade corridor in use from the early 1800s. During the 1850s gold rush, the same route became known as the Cariboo Trail, a major north-south transportation corridor between the Columbia Plateau and British Columbia.

Hiking, Caves, and Rock Climbing

The hiking trail is a 2.5 to 3 mile round trip with approximately 200 feet of elevation gain, rated easy, and managed by the Bureau of Land Management. No pass is required. The trail descends the canyon toward the Okanogan River through landscape recovering from wildfires in 2007 and 2015.

McLaughlin Canyon supports 103 documented rock climbing routes across eight areas on public BLM land, including the Last Wall and South Buttress. Routes range from 5.5 to 5.12 on gneiss, with 76 sport, 25 trad, and 2 toprope. All rock north of the county road is private and off-limits.

The caves on the southwestern slope of Tonasket Mountain are accessible year-round but require a headlamp and careful footing. Some passages involve short scrambles and tight squeezes. Spring and fall are the best seasons for hiking and climbing. Summer temperatures can exceed 100 degrees Fahrenheit in the canyon.

Rattlesnakes are present from April through October. The nearest services are in Tonasket, 4 miles north on Highway 97. From Seattle, the drive is approximately 4.5 hours. From Spokane, approximately 3 hours.