Giant Ripples of Camas Prairie EarthCache
Giant Ripples of Camas Prairie
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To validate this cache go the above coordinates and read the sign and answer the questions. Do not forget to identify the cache as Giant Ripples, the number of cachers, when you send me your answers. Do not post the answers but email them to mrmeany@donutholes.net
1. What are the dimensions of the larger ripples?
2. How deep was Lake Missoula here?
3. Describe the wildlife at the time of the Flood.
4. Bring a compass if your GPS do not have one. Face magnetic east and see how many ripples you can count in a straight line. Don’t try to use Google as you cannot see all of them from the sign. Include the time of day and the sky condition (sunny, cloudy, etc).
5. (optional pictures) I hope some of you with better cameras than mine will get some good pictures of the ripples and your party and post them with your log so everyone and see them.
GIANT RIPPLES
In 1886 T.C. Chamberlain was surveying glaciers in the Mission Valley for the US geological Survey (USGS) when he noted signs of faint watermarks wrapping among the hills. He concluded at one time a glacier lake was in the valley. He likened it to the famous glacier lake at Glen Roy, Scotland. Geologists had been studying Glen Roy since the late 1700’s (see the interesting articles in the references).
Joseph Pardee in 1909 was hired by the USGS to study the Glacier Lake Missoula. He was probably aware of Chamberlains notes on the old shore lines. It can be assumed Pardee likened them to the grassy hills above Missoula. All 1909 Pardee tromped the hills identifying the boundaries of the Lake. He then explored down the Clark Fork River toward Pend Oreille Lake where the watermarks stopped. He came to the conclusion that an ice dam had caused Lake Missoula. In 1910 he published his findings but did not speculate on the breakup of the ice dam or draining of Lake Missoula.
J Harlin Bretz was a high school teacher in Seattle when he decided to get a PHD in geology which he did in 1913. In 1914 at age 31 he became a faculty member at the University of Chicago and taught there until his retirement. At some time he began an interest in eastern and central Washington which he named the scablands. He spent summers with his family and students studying the unique features. In 1923, Bretz was 41 years old when he presented his paper on the catastrophic flood theory to the Geological Society of America. Even with a preponderance of evidence it was rudely rejected on the grounds that geology always took eons and eons to happen, surely not in a week or two, and when asked about the source of the flood, Bretz could not answer the question. In 1927 Bretz was asked to present his theories again and this time Pardee was in the audience and Pardee whispered to his friend “I know where the flood may have come from”. It is not known why Pardee did not support Bretz publicly; one suggestion was that Pardee had no proof of Lake Missoula draining rapidly.
For the first time in 1940 Pardee was flying high over the Camas Prairie when he noticed the ripples far down below him (see below to view what the ripples look like in Google Earth). The ripples looked just like what he would see in the beds of fast moving streams or the sand on the beach as tide was moving out. This proved to Pardee that the Glacial Lake Missoula had to have drained very rapidly to cause these gigantic ripples. In 1942 Pardee published his final paper on the lake and the rapid draining. But again his paper said nothing about where the water went and the aftermath it must have caused. Neither Bretz, nor Pardee tied both theories together publicly. Remember, each man had their full time job and only spent spare time on this mystery. By the 1950’s Bretz theories were finally being accepted by the younger geologist.
These ripples are important for two reasons: They proved Bretz theory that geological change can happen suddenly; and so far, they are the largest ripples ever found on earth. There are other ripple beds along the scablands and Columbia River that Bretz studied. NASA used this knowledge of ripples to study the ripples on Mars. They came to the conclusion that in the past history of Mars there were mass amounts of fast moving water that form ripples and they are much larger than the Camas Prairie Ripples. This leads the scientist to wonder if there is still ground water to be found and used by explorers and maybe settlers of Mars.
The above coordinates will direct you to a sign about the ripples. Facing north the road goes over Markle pass and to the east of the hill in front of you is Willis Creek Pass. Lake Missoula was much higher than the north hill and when the dam broke water rushed over the hill. As the lake lowered below the height of the hill it still flooded through the two passes. (See the picture below.) The ripples were formed when the lake bed water started to flush the bottom debris and all the debris the current could scrape away that was not attached to the bedrock. As the velocity of water doubles, its ability to move material across the bottom increases 64 fold and it can hold more particles in suspension. The power of the water was tremendously powerful and for these ripple to be formed, Allen & Burn estimated the depth had to be over 800 feet high and the velocity over 55 MPH. This terrific force would actually flow bottom debris up and over the top of the hills. The larger and heavier debris would be deposited closer to the top of the hill and these ripples are called antidunes. The steep side of an antidune always faces the current and is usually the larger of the ripples and further apart. The finer debris would form the lower ripples and are called normal dunes. The steep side of a normal dune always faces away from the current and are smaller and closer together. There are some antidunes but most of the ripples are classified as normal. There are 8 classifications of the wave shapes of the dunes in relationship to each other but these ripples are common and what scientist would expect. Since the ripples form at right angles to the flow path, you can easily follow the path down the hills (see Google Earth). The water flooded south to the Flathead River and then down the Clark Fork River.
There are over 6 square miles of unplowed dunes that are quite visible along both sides of the highway all the way to Markle Pass. Do not forget to drive to the top of the pass to get a better all-around view. There is a good pull off. I was there around 1:00 and the sun was bright and right above the prairie and it made the ripples look flat but my binoculars helped bring in the detail and they showed up better. With my cheap 5X zoom camera, none of my pictures turned out as good as I hoped. Early morning or late evening light would create shadows and you would be able to see them better. These earth caches are to be educational in nature and not just another number to rack up. Please explore the on line references as many have some amazing pictures.
REFERENCES
Cataclysms on the Columbia, Allen & Burns
Glacial Lake Missoula, David Alt
geology.mines.edu/faculty/Klee/Camas.pdf
www.undiscoveredscotland.co.uk/roybridge/glenroy/index.html
www.eh-resources.org/roy.html
Additional Hints
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