Mount St Helens

Mount St. Helens is an active stratovolcano located in Skamania County, Washington. Mount St. Helens takes its English name from the British diplomat Lord St Helens, a friend of explorer George Vancouver who made a survey of the area in the late 18th century. The volcano is located in the Cascade Range and is part of the Cascade Volcanic Arc, a segment of the Pacific Ring of Fire that includes over 160 active volcanoes.

Mount St. Helens is most famous for its catastrophic eruption on May 18, 1980, at 8:32 am. It was the deadliest and most economically destructive volcanic event in the history of the US. Fifty-seven people were killed; 250 homes, 47 bridges, 15 miles of railways, and 185 miles of highway were destroyed. A massive debris avalanche caused an eruption, reducing the elevation of the mountain's summit from 9,677 ft to 8,365 ft and replacing it with a 1 mile wide horseshoe-shaped crater. The debris avalanche was up to 0.7 cubic miles (2.9 km3) in volume. The Mount St. Helens National Volcanic Monument was created to preserve the volcano and allow for its aftermath to be scientifically studied. The Johnston Ridge Observatory sits on a bluff just 5-1/2 miles from the crater at an elevation of 4,314'/1,327m and offers grand views of Mount St. Helens and much of the 1980 blast zone. This visitor center is the closest you can get to the mountain by car when driving in from the west and is located 53 miles east of the town of Castle Rock at the end of State Route 504. Please allow a whole day for the visitor centers along Route 504 and hiking once you reach Johnston.



As with most other volcanoes in the Cascade Range, Mount St. Helens is a large eruptive cone consisting of lava rock interlayered with ash, pumice, and other deposits. The mountain includes layers of basalt and andesite through which several domes of dacite lava have erupted. The largest of the dacite domes formed the previous summit, and off its northern flank sat the smaller Goat Rocks dome. Both were destroyed in the 1980 eruption.


About 8 1/2 hours after Mount St. Helens blew its volcanic stack on May 18, 1980 a river of mud arrived in Kid Valley, some 25 miles distant. Reaching speeds on the way of up to 70 mph, the mud slowed to a leisurely 20 mph when it destroyed the homes in this forested hollow along Hwy 504. In Kid Valley, Washington a newly-built A-frame house filled with 200 tons of silt, mud, water and ash. While other signs of catastrophe are gone, the A-frame remains as part of a tourist attraction next to the North Fork Survivors Gift Shop.

Next to the A Frame house is the Mount St. Helens Bigfoot statue is 28-feet tall, made of concrete, with intricately detailed fur and a folklorish grin. It's as if, instead of fleeing from whirring cameras, he decided to stop and strike a cute pose. The owners of the Survivors Gift Shop decided to honor his memory when they built their original Bigfoot statue in the mid-1980s. It was slightly smaller than the current one, and made of combustible materials, as proved by its incineration by vandals in the mid-1990s.


The North Fork Toutle River is a tributary of the Toutle River in the southwestern Washington in the United States. The river has its headwaters near Spirit Lake, on the north side of Mount St. Helens, and flows about 30 miles (48 km) to the Toutle River, 22 miles (35 km) upstream of its confluence with the Columbia River.

Hoffstadt Creek Bridge is the largest and highest bridge along Washington State’s Spirit Lake Memorial Highway, Hoffstadt Creek is a deck truss bridge with a main span of 600 feet. Opened in 1991, the new highway was built to replace the original highway that was destroyed by the eruption of Mount Saint Helens in 1980. By taking an elevation high above the North Fork of the Toutle River, the new route 504 is safer from potential debris run off and flood damage. The continuous truss was built by erecting the outside spans of 332 feet on falsework and then cantilevering the central span of 600 feet from each side. The approaches are steel plate girders with spans that vary from 148 feet to 232 feet. The truss reaches a depth of 56 feet above the piers. The bridge cost 12.6 million dollars and uses 2,505 tons of steel. The bridge won the 1996 Merit Bridge Award for a Long Span bridge from the American Institute of Steel Construction Inc.