Logging tasks
- Message me the cache name, and let me know the group you are logging for if more than one. If you are not logging about the same time people will need to submit their own answers.
- Looking at the two sides of the canyon (north/south) what seems to be the differences in erosion?
- Near where the dam broke and on the North side, do you belive the dam removed more than the topsoil off that side of the rock (rocks, boulders or erosion in the stone? What?
- Is there evidence of the flood and erosion downstream?
- Take a photo of yourself, your GPS, your foot, or a paper with your geocaching name at the location.
Usually erosion is a slow process. Large boulders are broken down into smaller stones and carried away, Material breaks down and covers rocks and creates a sloped V shaped valley as materials fill the valley floor. The erosion that takes place makes the valley deeper and sides more of a v shape. Of course there are variations, steep canyons cut in bedrock. A wide valley may have steep sides, but in general there is a slow erosion from the sides, and down from the middle.
When the Dam was filled it reached approximatly 240 from the base to the level of the water. Usually when you see breaks they are slow, and they slowly break the dam. In this case water started seeping through the dam, though not unusual it gave away suddenly. When that broke, 2,000,000 cubic feet per second of water and dam material was carried away downstream. this went on for a few hours carrying material away, and tearing through one side of the dam and scouring down the canyon sides.
from the East Idaho News June 5, 2016 gave the account of Jay Calderwood
A wall of water – more than 20 feet high – thundered down the Teton River canyon, obliterating a power station and concrete plant below the dam in minutes. The water picked up hundreds of recently cut logs that lined the banks near the dam.
Those logs, along with heavy equipment, mud and debris, became battering rams.
“It was a frightening experience to see how much power (the flood) had,” Calderwood said. “I’ll never forget the water going down the canyon and hitting huge cottonwoods standing 60 to 80 feet tall, and that water was mowing them down like … they (were) mowing alfalfa.”
Photos courtesy of the BLM https://www.usbr.gov/pn/snakeriver/dams/uppersnake/teton/index.html