IMPORTANT: A pass or entry fee is required to visit Johnston Ridge Observatory.
To log this cache, first send the answers to the questions below to the cache owner and then immediately log your find so that the two arrive close together for easier tracking by the CO. If possible, send your answers via the message center; responses will be sent that way. If there are questions or if additional information is needed, you will be contacted.
Copy and paste the following into your response to the CO preferably through the message center. Questions are based on both observation and cache text.
1. Note the signs along the trail with footprints on them. How do they help with recovery of the land?
2. At the given coordinates, (outside, uphill) you will find a round object. Explain how this could be useful in determining your position in relationship to your surroundings.
3. How much altitude did the mountain lose as a result of the "Big Bang."
4. Mount St. Helens is a stratovolcano. What does this mean?
5. Determine two things (in addition to the crater in the mountain) that you can see that are results of The Big Bang.
Native American Legend
Northwest Indians told early explorers about the fiery Mount St. Helens. In fact, an Indian name for the mountain, Louwala-Clough, means "smoking mountain". According to one legend, the mountain was once a beautiful maiden, "Loowit". When two sons of the Great Spirit "Sahale" fell in love with her, she could not choose between them. The two braves, Wyeast and Klickitat fought over her, burying villages and forests in the process. Sahale was furious. He smote the three lovers and erected a mighty mountain peak where each fell. Because Loowit was beautiful, her mountain (Mount St. Helens) was a beautiful, symmetrical cone of dazzling white. Wyeast (Mount Hood) lifts his head in pride, but Klickitat (Mount Adams) wept to see the beautiful maiden wrapped in snow, so he bends his head as he gazes on St. Helens.
Before the “Big Bang”
In modern times, Mount St. Helens was known as "the Fuji of America" because its symmetrical beauty was similar to that of the famous Japanese volcano. The graceful cone top, whose glistening cap of perennial snow and ice dazzled the viewer, is now largely gone. On May 18, 1980, the mountaintop was transformed in a few hours into the extensive volcanic ash that blanketed much of the Northwestern United States, as well as various other types of deposits closer to the mountain.
Even before its recent loss of height, Mount St. Helens was not one of the highest peaks in the Cascade Range. Its summit altitude of 9,677 feet made it only the fifth highest peak in Washington. It stood out from surrounding hills because it rose thousands of feet above them and had a perennial cover of ice and snow. The peak rose more than 5,000 feet above its base, where the lower flanks merge with adjacent ridges. The mountain is about 6 miles across at its base, which is at an altitude of about 4,400 feet on the northeastern side and 4,000 feet elsewhere. At the pre-eruption timberline (upper limit of trees), the width of the cone was about 4 miles.
Like most other Cascade volcanoes, Mount St. Helens is a great cone of rubble consisting of lava rock inter-layered with pyroclastic and other deposits. Volcanic cones of this internal structure are called composite cones or stratovolcanoes. Mount St. Helens 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; another formed Goat Rocks to the north.
Mount St. Helens was recognized as a volcano at least as early as 1835; the first geologist apparently viewed the volcano 6 years later. James Dwight Dana of Yale University, while sailing with the Charles Wilkes U.S.Exploring Expedition, saw the peak (then quiescent) from off the mouth of the Columbia River in 1841. Another member of the expedition later described "cellular basaltic lavas" at the mountain's base. In the last 515 years, it is known to have produced 4 major explosive eruptions (each with at least 1 cubic kilometer of eruption deposits) and dozens of lesser eruptions. Two of the major eruptions were separated by only 2 years. One of those, in 1480 A.D., was about 5 times larger than the May 18, 1980 eruption, and even larger eruptions are known to have occurred during Mount St. Helens' brief but very active 50,000-year lifetime.
The “Big Bang”
Mount St. Helens began to show the first signs of volcanic unrest in March of 1980, signaling the awakening of the mountain from a 123-year slumber. Over the next two months more than 10,000 earthquakes followed as magma moved into the volcano, wedging the volcano apart at a rate of five feet per day, causing the north slope of the volcano to bulge and become unstable.
At 8:32 Sunday morning, May 18, 1980, Mount St. Helens erupted. A magnitude 5.1 earthquake triggered the collapse of the volcano’s bulging north flank and summit in a landslide of historic proportions. Magma trapped within the volcano, suddenly relieved of pressure, exploded outward in a lateral 300-mile per hour blast that blew down 230 square miles of forest in less than four minutes. A plume of volcanic ash and pumice billowed 15 miles into the sky, melting glacial ice and creating cement-like slurries of rock and ash called mudflows. These superheated (up to 300 degrees Celsius) avalanches of hot gas, ash, and pumice (called pyroclastic flows) flowed into the valley north of the crater, scouring surrounding river pathways. At the same time a mushroom-shaped column of ash rose thousands of feet skyward and drifted downwind, turning day into night as dark, gray ash fell over eastern Washington, across the United States, and in trace amounts around the world.
The eruption lasted 9 hours, but Mount St. Helens and the surrounding landscape were dramatically changed within moments. The resulting landscape was a seemingly gray wasteland. Following the eruption, there were 5 smaller explosive eruptions over a period of 5 months. Thereafter, a series of 16 dome-building eruptions through October 1986 constructed the new, 880-foot high, lava dome in the crater formed by the initial eruption.
Mount St. Helens, currently having a reduced altitude of 8,364 feet, remains a potentially active and dangerous volcano.
Sources: USDA publications