The sand dunes located within Petoskey State Park began during the Great Ice Age. In fact, as recently as 16,000 years ago Michigan was covered with glacial ice thousands of feet thick. At the end of this period, some 10,000 to 14,000 years ago the glacial ice retreated leaving behind glacial till known as “drift”. Today’s dunes are formed of sand that resulted from this glacial drift. There are presently over 40 occurrences of open dunes in Michigan that make up approximately 275,000 acres along this state’s shoreline.
The major types of sand dunes in the Great Lakes region include Fore Dunes, which are the first ridges behind the beach. Although fore dunes are above wave action most of the time, they are subject to storm waves. In Petoskey State Park these fore dunes generally are about two meters in height. Another type, and better-known dune are the Perched Dunes. These are the largest dunes and some of the more famous and spectacular land features in Michigan. They are actually made up of eolian sands (wind blown sands) perched atop glacial moraines. Glacial moraines, common landforms in Michigan, are ridges of sand, gravel, stone and clay left behind by retreating glacial ice. Some of the best-known examples of perched dunes can be found at the Sleeping Bear Plateau. Parallel Dunes are a series of low, linear dunes formed parallel to the shores of large shallow bays. The parallel dunes along the eastern shore of Lake Michigan were formed about 4,000 years ago during the Lake Nipissing stage of Lake Michigan, when water levels were 25 to 30 feet higher than present day Lake Michigan water levels. Rivers entering the bays carried abundant sand, which was then moved along the shore by lake currents. Blowouts are also a type of dune created by the destabilization of sand dunes. Typically these originate on the summit or windward face of parallel dunes. Often rapidly formed by the wind, creating narrow channels and exposing plant roots. Blowouts can create interruptions in the shape of parallel dunes that may result in deeply carved indentations called “parabolic dunes”. These are so named because of their saddle shape or “U” shaped structure.
As mentioned previously, eolian sands create sand dunes. These sands migrate with winds and other natural actions, which eventually settle and build up over time to form dunes. Evidence of these eolian sands can be seen in the “Day Use” parking lot and roads near the beach at Petoskey State Park. You will probably see “sand drifts” across these and other similar areas. As these sands advance further inland, more vegetation grows and captures these sand granules. Eventually you will find denser vegetation growing as you move inland until you find completely forested dunes. The larger parabolic dunes represent the oldest specimens within the park. They are found primarily on the eastern border of the park and even further east, almost fronting US-31. These larger inland dunes vary in height between 30 and 40 meters. Generally speaking, the smaller and more active dunes, which are advancing between 4 and 5 feet per year, are located closer to the beach, while the larger and more stabilized dunes are found further inland.
Sand dunes are fragile creations and subject to destabilization through nature and more often the actions of man. Please be respectful of the dunes and stay off of them except in designated areas and trails (such as Old Baldy).
To log this find, e-mail me the answers to the following questions:
1. At the posted coordinates, face south to southwest. Looking at the dune directly in front of you, in your best estimate what is its height?
2. Next, take a very short drive/walk to 45º 24.434N - 084º 54.607W
Note: You can drive to within 30 feet of these coordinates.
No need to bushwhack. Look for a small picnic area and circle drive.
Once at this location, face west to northwest.
Looking up the hill in front of you, what natural occurrence do you see? (Hint: It is often windy here.)
a). Stabilized dunes.
b). Advancing eolian sands and active dune formation.
c). Gullies being formed by severe erosion.
d). Osama Bin Laden playing poker with Kim Jong-Il and Sadam Husein.
Pictures not required, but always encouraged.
Please note that you will need either a “Day-Pass” or an “Annual” sticker for entry into the State Park. This sticker will be good for ALL Michigan State Parks. While there you may also want to try your luck at finding the Michigan State Stone (the Petoskey Stone). These are often found along the shoreline. Also located in the park is the traditional cache “3 Little Monsters in Little Traverse Bay” (GC8781), which is the oldest geocache in Emmet County. Happy hunting!
6/02/08 - Congratulations to johnny angel on the FTF!