Munro Glacial Deposit EarthCache
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This cache is on top of a hill. The road is blacktop so it is easy access to cords. Please park at cords N45* 37.934 W084* 40.284 for a short walk to top of hill for a great view.
Glacier Reveals its Age!
In 1965, the University of Michigan was able to pinpoint the date of the state’s last glacial ice advance from a fossil moss sample in Munro Twp. A local farmer began digging a pond just off Munro Lake. At a depth of 10 to 12 feet, he came across some buried plant material. The farmer was curious about the unusual material and deposited some of it on his back porch. Later he contacted the University of Michigan scientists of the Biological Station at Douglas Lake. He discovered a compressed layer of moss which had been buried under silt, then covered by glacial till, a mixture of clay, sand, gravel and stones laid down by an advancing ice sheet. The Michigan scientists studied the fossil moss, which looked like a layer of old felt half an inch thick. Samples of the moss where carbon-dated and found to be about 12,650 years old, plus or minus 600 years. Imbedded in the layer were pollens which told the scientists what plant life existed in the area 12,000 years ago and gave other indications of the climate and geological conditions of that time. The scientists theorized on the basis of pollen deposits that the moss probably grew in an open, nearly treeless area. The moss bed was then buried by silt which may have been deposited by waters impounded by the advancing ice. Later the ice deposited the thick layer of glacial till. Ground water from nearby Munro Lake helped preserve the buried moss in relatively good condition. The date tied in with other figures for the most recent continental ice advance over the Great Lakes region, but it was the first time scientists were able to date the advance of the ice sheet in lower Michigan.
At the posted cords you are standing approximately ½ mile from this little pond, however, it is located on private property and it is not accessible. The pond is surrounded by several glacial landforms including moraines, kettle lakes, an esker and glacial lake plains.
To log a find on this beautiful scenic Earthcache you must e-mail the following:
1.) At the posted cords, what landform are you standing on?
2.) What landform is in the SSE direction?
3.) What landform is in the SSW direction, beyond the Kettle Lake Munro?
4.) What landform is in the North direction?
5.) There is a man made landmark above the tree line in the NNW direction. What is it?
6.) Post a picture of yourself and GPSr with your favorite landform in the background. (pic optional of course)
Bonus Question: If you are a local resident, tell me, if you know: Who is the local farmer credited for turning up the fossil moss allowing scientists to date the last glacial ice advance over the Great Lakes region?
Quick definitions of these glacial landforms:
1.) Ground Moraines - An ice glacier moves debris during its advance and retreat. A ground moraine forms when the ice glacier melts away and a blanket of till is laid down. Ground moraines are defined as till covered areas with irregular topography and no ridges. They appear as gently rolling hills or plains.
2.) End Moraine - End Moraines form when the ice glacier moves forward, or retreats, leaving ridges of unconsolidated debris deposited at the front edge. They usually reflect the shape of the glacier's front edge. Glaciers act like a conveyor belt carrying debris from the top of the glacier to the bottom where it deposits it in end moraines. The longer the edge of the glacier stays in one place the larger the end moraine will be.
3.) Kettle Holes / Kettle Lakes - As an ice glacier retreats, sometimes large blocks of ice break off the glacier. The blocks of ice are buried in the glacial till. After the ice melts away, a steep-sided depression is left in the till creating kettle holes.
Kettle Lakes - Kettle Lakes form the same as Kettle Holes, but they are below the water table. The depressions fill partially or completely with water, forming kettle lakes. Kettle lakes are usually very small, and are more like ponds than lakes.
4.) Esker - Melting ice forms tunnels and rivers flowing under or through an ice glacier. Gradually, the tunnels become choked with gravel debris. When the glacier melts away, long steep-sided sinuous ridges are left. Eskers range from 1 mile long to over 100 miles long. Eskers are much less common than moraines or kames. The term “hog-back” is commonly used to describe the side view of an esker.
5.) Glacial Lake Plain - Glacial Lake Plains are the flattest areas of Michigan, the result of deposits on the bottom of glacial and pro-glacial lakes.
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