When people visit this city, I always get asked why it is called Great Falls. Today you will have the opportunity to learn that the city is called Great Falls because there is a series of 5 waterfalls. You will learn how these waterfalls were created and a bit of history.
Today only 4 of the 5 waterfalls are visible due to the hydroelectric dams along the Missouri River. I’ve included some optional waypoints if you wish to see each of the waterfalls.
Each of the five falls of the Missouri is caused by the presence of a resistant sandstone unit in the Cretaceous Kootenai Formation. A “formation” is an extensive rock body deposited as a particular type of sediment. The Kootenai Formation consists of sedimentary rocks formed from sand and silts that accumulated in a shallow body of water, millions of years ago. The formation includes alternating layers of siltstone, shale, and sandstone. The city of Great Falls is built on the crest of a gentle fold know as the Sweetgrass Arch. As the river has cut down through the arch, it has encountered the resistant sandstone layers resulting in the set of waterfalls that drops the river numerous feet over several miles.
To log this Earthcache, please e-mail the answers to the following questions (The answers can be found on the informational signs nearby. Please do not post answers in your log.) Or optionally you may post a picture of you with the falls in the background.
1. How many years ago was the Kootenai Formation formed?
2. How many feet does the Missouri River drop over how many miles?
3. What are the names of the five waterfalls of the Missouri?