Cochise College
Student Papers in Geology
Geology Home Page
Roger Weller, geology instructor
wellerr@cochise.edu
Tahquamenon Falls, Michigan
Emily Woodmansee
Historical Geology
Spring 2005
Fall 2004
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.
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. 7th 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