Lake Missoula "Pebbles" EarthCache
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This is an earthcache designed to get you familiar with the area known as the Columbia Basin. At the end of the last Ice Age, a great flood came through this area and carved out the canyons surrounding you at the location of this geocache. Please read the following to understand this massive flood.
(This information comes from (visit link)
Between 2 million and 2.5 million years ago a combination of cooler temperatures and increased precipitation formed massive ice sheets which repeatedly advanced and retreated as climate conditions fluctuated. Ice coated the Puget Sound lowlands, and most of the mountain regions of northern Washington, Idaho and Montana. So much glacial ice existed that the oceans were 300 feet lower than they are today. The final episode was the Wisconsin glaciation, a cycle that took place from 100,000 years ago until about 10,000 years ago.
As the ice sheets pushed southward from Canada they interrupted normal stream flows in the deep valleys of the mountainous Pacific Northwest. One protrusion, the Okanogan Lobe, created Lake Columbia, which was a super-sized version of modern Lake Roosevelt. An ice mass clogging the Purcell Valley of Idaho's panhandle blocked the outflow of the Clark Fork River, forming Glacial Lake Missoula. Other impoundments included a lake near Spokane, Wash. Scientists believe that additional lakes existed in Washington, Montana and British Columbia.
The ice blockage in the Purcel Valley gradually collected tremendous volumes of water in the deep valleys of western Montana, creating a gigantic reservoir which attained a depth of 2,000 feet and impounded over 500 cubic miles of water--equivalent to the combined volumes lakes Erie and Ontario. The natural ice dam periodically failed, which caused a catastrophic emptying of Lake Missoula. After each dam failure, the southward moving ice sheet then created a new one, and the cycle repeated itself. At least 40 major flood episodes originated from Lake Missoula.
Each ice dam failure released a torrent of of water hundreds of feet deep, which swept southwesterly--gouging the huge coulees of eastern Washington, ripping out sediment and basalt rock, and stripping soil and vegitation from thousands of square miles of land in the Columbia Basin. Some of the debris was carried by the floods all the way to the ocean. One flood pathway created the Grand Coulee. A second poured into the lowlands around Ephrata, Moses Lake and Othello. A third flowed along the western fringe of the Palouse Hills, removing vast amounts of fertile topsoil."
What you see at this location are some of the "pebbles" carried by this massive flood. If you look to the north, you will see the canyon where the water rushed at a high velocity, only to slow once it opened up, thus losing momentum and dropping these stones.
In order to log this cache, you must do two things.
1) Take a picture of yourself at this point and post it with your log. Try to make it so it does not give away the answer to number two.
2) Estimate the number of boulders in a 10,000 square foot plot (100 feet by 100 feet). E-mail that answer to me. Do NOT post it with your log!
Enjoy the scenery, and I hope you enjoy this area as much as I do! Cache on!
Additional Hints
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