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## After the "Big Bang"

A cache by ohjoy! Message this owner
Hidden : 07/18/2005
Difficulty:
Terrain:

Size:  (other)

#### Watch

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## Geocache Description:

Please note - only messages sent through the message center will receive responses from me if I am out of town due to lack of good internet access. I will send complete responses when I return. Please log your found as soon as answers are sent.

This cache will take you to two locations where you will be able to see how plants are returning and thriving on the sterile landscape resulting from the devastating 1980 eruption of Mount St. Helens. The posted coordinates will take you to a viewpoint. The second location is on the side of the road where you can remain in your car while making the needed observations. An $8 daily or$30 annual Northwest Forest Pass is necessary for each vehicle visiting this area.

1. During your drive to the cache site, estimate the diameter of the larger stumps from trees destroyed by the blast. Then select a newly grown Douglas Fir and estimate its diameter. Compare the diameters of the stumps and the newly grown trees and make a guess as to how many years it may take for the small new trees to reach the size of the destroyed trees.
2. Using the text and your observation at the site, name at least two geological results of of the eruption that will continuously affect the growth of new trees.
3. At the posted coordinates, find a bench and tell me something about Bill and Sue.
4. Drive to the general area of N 46° 17.136 W 122° 15.191 and explain what you see on both sides of the road related to devastation and regrowth. (If you are stopped by a closed gate before arriving at this second location, state this in your log and do your best to answer this question.
5. Required - a photo of yourself at the main cache site overlook. If camera shy, include your name written on paper or a name badge in the photo.

The “Big Bang” Event
On May 18, 1980, Mount St. Helens erupted. The sound of the blast was heard hundreds of miles away and the effects of the blast were even more widespread.
The lateral blast, which lasted only the first few minutes of a 9-hour continuous eruption, devastated more than 150 square miles of forest and recreation area, killed countless animals, and left about 60 persons dead or missing. The eruption caused pyroclastic flows and many mudflows, the largest of which produced deposits so extensive and voluminous that they reached and blocked the shipping channel of the Columbia River about 70 river miles from the volcano. The ash, which fell in troublesome amounts as far east as western Montana, severely disrupted travel and caused widespread economic loss.

What would be the long-term results of this eruption?

The “Big Bang” Recovery
In 1982 the President and Congress created the 110,000-acre National Volcanic Monument for research, recreation, and education. Inside the Monument, the environment is left to respond naturally to the disturbance.

Plants and Animals: Although areas around Mount St. Helens appeared barren and lifeless after the 1980 eruption, some plants and animals did survive. Pocket gophers in underground burrows, fish in ice covered lakes and salamanders hibernating in mud were protected from the hot, stone-filled wind of the lateral blast. Plants such as willow, vine maple and black cottonwood were able to re-sprout from roots protected in moist soil.

Despite surviving the eruption, many of these plants and animals were unable to survive long-term in the harsh new environment. However, a few were able to tolerate the extreme conditions and help pave the way for new colonizers. Winds brought light seeds and insects to the area. Plants and insects attracted birds, deer and elk. Heavier seeds rode in on the feathers of birds and in elk droppings. Ponds and springs created by the eruption became the centers of life for survivors and colonizers.

Today, many areas around the volcano still have a desert-like appearance, but the vast majority of plant and animal species that were found at Mount St. Helens prior to the 1980 eruption have returned. Some, like the Roosevelt elk have returned in numbers that far exceed pre-1980 populations. The interactions of these plants and animals with the land they live on remind us of the interconnected world we live in.

A New Glacier:
At Mount St. Helens, geologists are carefully monitoring the growth of North America’s youngest glacier. In the crater, much more snow falls each winter than melts during the summer. The almost perfect north-facing amphitheater, formed by the crater walls, shades this snow. Rocks that tumble to the crater floor insulate this growing mass of snow and ice. Time and pressure from over-lying snow slowly change this snow to ice.

Since 1982, scientists estimate that the thickness of the ice mass has increased by nearly 50 feet each year. Surface cracks suggest that the ice mass is beginning to move. As the size of the ice mass increases it may begin to erode the lava dome it surrounds. Today, the snow and ice in the crater is equal in volume to all of the pre-eruption glaciers on Mount St. Helens combined.

The Dome:
In late September 2004, after 18 years of relative quiet, hundreds of earthquakes signaled Mount St. Helens’ reawakening. Activity increased, producing the first steam eruption on October 1st. Over the next ten days larger steam explosions showered the crater and flanks with ash, and a portion of the crater glacier began to swell, as magma moved under the crater’s ice and snow.

By October 11th, the first small fin of new lave broke the surface. The thick, pasty lava formed a lava dome, a common feature of Cascade Volcanoes. The new dome grew at a steady pace, about a dump truck load every second through December. By February of 2005, the pace of the lava extrusion had slowed, but the new dome “Whale Back” was already over 1450 feet high and 1600 feet long.

The history of Mount St. Helens provides insight into future activity. The volcano has long been the most active in the Cascades, eruption every 100 to 150 years over the past 2,000 years, often explosively. The current eruption may continue for months or even years, quietly rebuilding the volcano, or it could stop as abruptly as it began.

Whatever the future holds, this eruption reminds us of Earth’s dynamic nature!