Are you ready to climb the sand dunes? You can but only in designated areas. This cache will take you to that location. First we are going to learn how they got here, when they got here, how long they will be around and why you are any allowed in climbing areas.
The dunes before you began with the Ice Age. About ten million years ago the earth began to cool which lead to the Ice Age which lead to the great Ice Age of the past two million years. The continental glaciers alternately advanced and retreated that produced glacial and interglacial times. The glaciers covered Michigan and large parts of Ohio, Indiana and Illinois. It has only been 11,800 years that the last glacier retreated from this area. The movement of the glaciers carried rock stone and sand along with it. They also caused the lake water to rise and fall. With this combination the Michigan shoreline base was created. The deposits caused land to jutted out into the lake creating highlands. The sand dunes themselves are estimated to have been here about 2 thousand years.
The highland here is the Sleeping Bear Plateau and is the base that supports these dunes. The dunes here are classified as "perched dunes". The perched dunes of the Sleeping Bear Plateau are actually a relatively thin blanket of wind blown sand resting on a thick deposit of sandy glacial debris. When the wind reworks the upper layers of the glacial sediment, sand is deposited into the dunes while the coarser material remains behind as lag gravel. Silt and clay-sized particles are so light that they remain suspension and travel a long distance before settling. The wind is an effective sorting agent and dune sand shows little in variation in size. Ice, wind and water move the sand here so it is continually changing the land of the surrounding area.
The Sleeping Bear Dunes are very active and have been advancing from there beginning. Currently the dunes have been moving rather quickly. 100 years ago the dunes were about 235 feet at the knob on the tall dune. The area that we are bring you to is currently moving at a rate of about 4 foot per year. There have also been a couple of large masses of the dune fall into Lake Michigan over the past century. So the question still remains will the dunes continue to erode, how long will they last? No one can say for sure because of the movement it may just move farther along the shore.
Your job here is to help log the movement of these dunes. This is going to be some work because it is time for you to climb the dunes.
1. Take an altitude reading from the flat ground at the bottom of the dunes. This will let us know the sand migration into the lowlands.
2. Climb to N44 53.255 W86 03.033. Take an altimeter reading there. This reading will show us how much of the dunes are migrating from the climbing area.
3. You will need to visit the beach on Lake Michigan at the dunes. This can be done one of 2 ways.
Option 1. If you are up for the walk it is worth taking the time to cross the dunes. It usually takes us about 2.5 hours to make the round trip across the dunes. Once you make it to the lake take an altimeter reading here. Post a picture of yourself on the beach so that we can see both the lake and the dunes in the background.
Option 2. You will have to drive to the beach at Empire. You will find parking at N44 48.825 W086 04.050. Once there you will need an altimeter reading. Here you will also need to past a picture of yourself with the replica lighthouse in the back ground.
E-mail me with the results of the first test. Then find the difference between #2 and #3 altimeter reading, include this result in the e-mail. Post your photos.
You may not want to attempt this cache in the off season. Though a beautiful time to be here the snow will get a sand covering. This can be deceiving and can be a deep plunge.
You will need to purchase a park pass to enter the parking area. You will have to stop at the visitor center to purchase your pass. The Sleeping Bear Dunes National Shoreline visitor center can be found at N44 48.685 W086 03.375. For more information on fees and schedule go to www.nps.gov/slbe.
Be sure to e-mail me within 7 days of logging the cache to get credit for your work. If the rules of finding an Earthcache and e-mailing the owner is not followed your log will be deleted without notice!