Elevation: 7,814 ft
This p2k summit is not in the book.
Southwest Butte is the highpoint of a small group of mountains between the Salmon River Canyon and the high mountains of the Gospel Hump Wilderness to the east. The butte is the high point across approximately 40 miles between the Gospels and the Seven Devils. The area is a long ridge system that divides the Salmon from its large tributaries of Allison Creek and Slate Creek. Only a few mountains along the ridge have enough prominence to be considered mountains.
The area is interesting due to the extreme abrupt lift from the bottom of the Salmon Canyon. The greatest elevation change is over 6,300 feet, with almost the entire area being well over 1 mile above the canyon bottom. To the east, the summit pyramid rises 1,400 feet over the headwaters of the West Fork of Allison Creek and over 6,000 feet above the confluence of that stream and the main form of Allison Creek, approximately 4 miles away. The long southwest ridge forms the divide between the main Salmon Canyon upstream from Riggins and the lower Salmon downstream from the confluence of the Little Salmon River. The 7,814-foot Southwest Butte has an impressive 2,354 feet of prominence.
The high vertical lift gives the Southwest Butte and its neighbors varied ecological gradation ranging from hot canyon grasslands, through open pine savannahs to moist mixed conifer forests followed by cool lodgepole pine forest before the high parklands of subalpine fir and whitebark pine. High elevation sage brush areas are also present with beautiful early season wildflowers. Such communities high in the mountains are unusual for the north portion of Idaho. There are also some high, cool basins dominated by subalpine fir and spruce as well.
Geologically the mountain is complex having basalt, limestone, quartz and granite components. Much of the area is formed by a granite batholith that cooked some of the base layers into various forms of quartz and schist. The limestone remains from the ancient Pacific shoreline. This shoreline was forced into the North American plate when the Wallowa Terrane pushed in from the west. Covering much of the lower to mid-elevations is more recent basalt from the Grand Ronde lava flows that flooded much of the inland northwest approximately 18 million years ago. An Idaho endemic plant that is limited to highly decomposed granitic soils is found on Southwest Butte, well separated from its more typical range further east.
A large forest fire in 2003 left the top of the Southwest Butte and much of the land to the north and east charred and barren. Regardless, it’s a nice, easily accessible destination. The views ranging from the hot Salmon Canyon below up to the jagged peaks of the Seven Devils provides a huge contrast in landforms and vegetation across 7,800 vertical feet. The view to the east up the main Salmon Canyon and the south up the Little Salmon Canyon provides a rare intermingling of huge holes in the ground divided by high peaks. Patrick Butte to the south rises 7,000 feet from the Salmon. The mountains in this area are not terribly high so they often go unnoticed, however; their bases are much lower than most places in the west to provide tremendous overall relief. Southwest Butte is uniquely situated to take in much of this fabulous country.
Approximately 15 miles north of Riggins, Idaho, on Highway 95 take the Slate Creek Road east. This road is found on the north end of the developed area that includes the Slate Creek Ranger Station and a couple dozen private homes at the mouth of Slate Creek. Follow the road for 0.3 miles where the actual State Creek Road merges to the left. Stay on the pavement (to the right) and continue for 0.3 mile to the Nut Basin Road (Forest Service road 441). Turn east on the Nut Basin Road and climb out of the canyon. Continue for approximately 17 miles on the Nut Basin Road to the Southwest Butte trailhead. This location is on a broad curve, and there is room to park two or three vehicles.
Another route into the area from Riggins goes east on the Salmon River Road for 9.5 miles to the mouth of Allison Creek. Turn left on the Allison Creek Road (Forest Service road 221) and follow it for 16.2 miles to the trailhead. There are a couple intersections to be aware of. About 3 miles after the road leaves the bottom of Allison Creek, turn left on the 535 road. After nearly 4 miles, merge left (continue straight) on the 441 road and continue to the Southwest Butte trailhead. This will be about 0.1 mile before the turnoff to the Nut Basin highpoint.
Trail Route (Class 1+)
The trail is only a little over 2.0 miles into Southwest Butte. Older maps show the trailhead to the east of the ridge top curve in the road, but this is no longer accurate. Much of the trail is on a very old road bed and the beginning has been obliterated. Now the trail is right on the ridge top curve. Follows the broad ridge line for a short distance before meeting the older trail surface after approximately 0.25 mile. Continue along the gentle higher elevations before coming to a south aspect. Here, drop down to a flat meadow area at the north end of a large basin on the northeast flank of the mountain.
In the vicinity of the northeast basin a trail goes to the west. Ignore this trail and go south through the basin. Small openings in a spruce/fir/lodgepole pine forest are found before the trail climbs up to the strange lunar northeast ridge of the mountain. The ground here is formed by coarse, powdery granite soil with very little vegetation. The trail then turns to the southwest and continues to climb over the main southwest ridge of the mountain. Once on top of this flank, leave the trail and hike cross-country up the summit ridge to the top. This is only about a 200 foot climb on moderately steep ground. Return can be by the same route or continue on the main north ridge from the summit and encircle the northeast basin, dropping back down to the trail at its north end. Then follow the trail back to the trailhead.