"The Sacred River"
15 million years ago, lava started spewing from the planet, forming the Columbian Plateau in what is now eastern Washington and Oregon and western Idaho. About 11 million years later, the flows stopped but were already hundreds of feet deep and covered up to 80,000 square miles of that area.
Between 16,000 and 12,000 years ago --- a blink in geologic time --- the last Ice Age was coming to an end. One lobe of the Cordilleran Ice Sheet was blocking the western end of what is now called Lake Missoula. This huge lake, located at Missoula, Montana, held over 500 cubic miles of water (about half the volume of Lake Michigan) and was held back by an ice dam about 2500 feet high. As the leading ice lobe was undercut by the water, a catastrophic flood broke through and surged down the Clark Fork into the Columbia Plateau, scouring out the volcanic deposits and creating what are now called the "channeled scablands."
Most of the cliffs and hills in this area are made of _____ from enormous lava flows that covered the whole region about 15 million years ago. Much more recently, huge floods swept across the landscape during the last ice age (See above). For the last 12,000 years, the Spokane River has continued to sculpt and shape the valley.
Resources: Signage at the posted coordinates.
To claim this Earthcache you will have to answer the following questions and email me (PaneledZero@gmail.com) the answers. Please do not post answers in your log, If answers are posted, your log could be deleted without warning. Make sure to post a photo if you can! Thank you!
1. Visit the information center at the above coordinates. The answers to questions 2 & 3 & 4 can be found here.
2. Face NORTH looking across the road and look up the hill, you will see a rock formation. Describe the formation. What type of rock is it?
3. During the last ice age how deep and fast was the flood when it passed through this area?
4. Falls were created in places where what type of rock restricted the carving action of the river?
Extra Credit: In a short sentence, explain how you think the rock formation survived the great flood?