"There are two hike possibilities from the Lava Canyon Trailhead: a short loop past some of the best waterfalls at Mount St. Helens, and a difficult descent of the Muddy River Gorge, aka Lava Canyon. Whichever hike you choose, the first 0.3 mile is paved and barrier-free. This lahar split near the present site of Lahar Viewpoint, with part of it racing down Pine Creek. The rest rushed down the Muddy River Gorge, aka Lava Canyon, removing all the vegetation as it went. Below the gorge the lahar continued down the Muddy River, smashing and carrying away almost everything in its path and depositing a large volume of logs into Swift Reservoir. This is not the first time a lahar has scoured the timber from Lava Canyon. Geologic evidence shows that this has happened before and in all likelihood will happen again." Read more
"This hike begins with the wide, paved Lava Canyon Interpretive Trail, which leads to a viewing platform overlooking a stunning canyon—a deep, jagged cut through a thick layer of ancient lava. From the viewing area, the trail loops down to the canyon rim in a long series of steep (for wheelchair users) switchback turns offering excellent views. The Muddy River cuts through the heart of this basalt canyon, which was scoured clean by the rushing mudflows during the 1980 eruption. The main Lava Canyon Trail continues east along the wild gorge of the Muddy River. You won’t find grand vistas or sweeping panoramas here. You will find a remarkable lesson in geological change—this valley was carved in part by a massive lahar, or volcano-induced mudflow of massive proportions." Read more
"First, a little history, so you’ll know what you’re looking at: In ancient times, a forest covered a deep valley. Then, 3,500 years ago, Mount St. Helens erupted, sending a massive mudflow down through the canyon, filling it with volcanic rock. Over the years, the river carved a path through the rock, forming a canyon with waterfalls, deep cuts, and towers of harder rock—Lava Canyon.
Later mudflows covered all of that, and eventually forest grew back over the whole thing. Then, on May 18, 1980, Mount St. Helens erupted again, melting 70% of its glaciers in an instant and sending millions of cubic feet of mud and rock blasting down the side of the mountain at about 45 miles an hour." Read more