Tahquamenon Falls, Michigan
Emily Woodmansee
Historical Geology
Spring 2005
 

                                      Tahquamenon Falls

 

Where are the falls located and what makes them unique?

 

            Tahquamenon falls are located in the Upper Peninsula of Michigan; they are approximately 50 million years old, putting them in the late Cambrian or Paleozoic period.  They consist of two sets of falls, the upper and lower falls.  The upper falls dispense over 50,000 gallons of water a second and are said to be the second largest waterfalls east of the Mississippi River, with Niagara Falls being the first.  The lower falls, although they are not as large, are no less extravagant than the upper falls.  They are found four miles down stream and consist of five sets of falls surrounding an island.

            These falls are a part of the Munising formation of the Lake Superior group; they are in the St. Croixan series of the late Cambrian period. One of the most extraordinary features of these falls is their unique amber color.  This color is attributed to the tannic acid released from the cedar and spruce trees and hemlock swamps that feed on the river.  These two sets of falls are each unique in their make-up and hold their own set of “finger prints”.
 

In the beginning…
 

            Many of the mountains that had been forming during Precambrian times were continuing to expand over the Upper Peninsula and into Canada and Wisconsin (referred to as highlands), streams flowing northward carried sand and gravel into the northern edge of the Upper Peninsula, the present Keweenaw Peninsula and Lake Superior.  Early into the Cambrian period these streams slowed down and gathered into channel ways and lakes, the coarse gravel and sand deposits that resulted from these water gatherings included many rocks and minerals that were eroded from the preexisting Precambrian rock.  These deposits are called the Jacobsville Sandstone, and form the oldest Cambrian formations in the Upper Peninsula.  The thickness of Jacobsville varies from 46 feet to 1100 feet depending on where it is laid, and the red color makes them one of the most beautiful rock types in Michigan.
              

            After the time when the Jacobsville sandstone was being laid there was a time of uplift and tilting creating an unconformity, which shows a lapse of several million years.  By the Late Cambrian period water had begun to spread into the Northern part of Michigan eroding away the Precambrian rock and Jacobsville sandstone while laying down the remaining quartz deposits.  These ancient sands formed the Chapel Rock Sandstone member of the Munising Formation, which Tahquamenon Falls is a part of (Dorr and Eschman).

            The Munising formation continued to spread over the Upper Peninsula eroding away these highlands.  Canadian waters were also eroding away Precambrian rocks, and sediments were being laid down into the northern part of Michigan.  These sediments carried a slightly different composition from the Chapel Rock sandstone and they became the Miner’s Castle Sandstone of the Munising formation, this type of sandstone slowly eroded into cliffs and escarpments like that of Tahquamenon Falls.  The Au Train dolomite was then laid down on top of the Miner’s Castle Sandstone as a more resistant layer.  In some areas fossils of cephalopods, conodonts, brachiopods, and gastropods are found in the Early Ordovician period within Au Train dolomite layers.   Since then the Tahquamenon River has eroded away some of the powerful deposits and exposed the Cambrian rock of the falls (Dorr and Eschman).
 

The Lower Falls
 

The lower falls formed before the upper falls, which is a prime example of the Nicholas Steno’s law of superposition, where in any succession of strata, the oldest lies at the bottom with the younger layers laying above (Prothero and Dott).  The layers forming the lower falls were laid down at an even rate making them very well sorted with particles of similar size within each layer.  The lower falls consist of mainly the Chapel Rock Sandstone, specific to the Cambrian period, and quartzite.  The Chapel Rock Sandstone is similar in age to the Dresbach Sandstone, which was forming at the same time along the southern side of the Northern Michigan.  It is now located in the Lower Peninsula and in adjoining areas of Wisconsin, Illinois, and Minnesota.  Along the northern bank of the lower falls ancient ripple marks appear in the sandstone showing cross-stratification.  The particular direction of the ripple marks indicates the direction of the wind or water current when they were being formed. 
 

                                                                          “Western Michigan University” 

The Upper Falls
 

            Of the two falls, the upper falls are by far the most magnificent sight to see.  They are 200-feet wide and fall powerfully, 48-feet, into the canyon, creating foam, which when mixed with the amber colored water looks like root beer.   It is because of this that they got the nickname, the “Root Beer Falls”.  The upper falls consist of Minor’s Castle Sandstone with the harder Au Train dolomite lying on top of that, and are made up of 90% quartz.  The Minor’s Castle Sandstone is similar in age to the Franconia Sandstone found in Lower Michigan, Wisconsin, and Minnesota.  Fossils of trilobites have been found in Miner’s Castle Sandstone, which suggest that marine life existed during the formation of the upper falls.  When the upper falls were being formed there was much more turbulence in the water causing the layers to form at a varied rate, which left poor sorting of the layers and minerals of different shapes and sizes within each layer. 
 

What does the future hold for the falls?
 

                The icy winters of Northern Michigan have caused much erosion of the upper falls and are causing it to slowly move up stream. The upper falls consist of harder more resistant layers over top of softer layers and because of this the  walls are eroding from underneath.




“Permission to copy from Gina Harman”

The falls have a wonderful history.  They are hidden in the midst of the woods, with the sound of the rushing waters and the singing birds flooding the viewer’s ears.  The falls seemed to be uninterrupted by the effects of our advancing society, when you are there, it is as if you are discovering them for the very first time.  They truly capture the power of nature and the essence of Northern Michigan.
 

Links:

http://www.superiorsights.com/information/tahquamenonfalls/

http://www.geo.msu.edu/geo333/rock-type.html

http://www2.nature.nps.gov/geology/parks/piro/

http://homepages.wmich.edu/~c9reinha/waterfalls.html

http://www.geo.msu.edu/geo333/rock-type.html

References

Dorr, John A. and Eschman F. Donald. Geology of Michigan. The University of Michigan 1970.

 

Harmen, Gina. “Tahquamenon Falls: State Park”. 16 April 2005.

            http://www.superiorsights.com/information/tahquamenonfalls

 

Prothero, Donald R. and Robert H. Dott Jr. Evolution of the Earth. 7^th ed. New York, NY 2004. The Mcraw-Hill Companies.

 

“Waterfalls in the Upper Peninsula”. Western Michigan University. 2002. 16 April 2005.

            http://homepages.wmich.edu/~c9reinha/waterfalls.html