The Great River Katahdin EarthCache
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This cache was originally placed by Northwoods Explorer.
This earthcache is a road trip along a well-known glacial formation called the Whalesback. This two-mile section of route 9 is part of the great Katahdin Esker formed during the most recent ice age.
The story of this once great under ice glacial river begins as do so many other landscape stories in Maine, with the glacial retreat. The last glacial episode in Maine began about 25,000 years ago, when the Laurentide ice sheet moved south overspreading New England and Eastern Canada. During its peak development, this ice sheet was centered over northern New England and the Maritime Provinces slowly flowing to the southeast into the ocean. The ice itself was thousands of feet thick, with its massive weight shaping the land as it slowly traveled. Climatic warming forced the Laurentide ice sheet to stop and begin to recede as early as 21,000 years ago. This melting of the ice sheet released more water then is possible to imagine.
As the retreating glacier halted for a time the margin would stabilize, thickened as it did in the area of Pineo Ridge where it formed a large delta at the oceans edge. But it is under the glacier that this story unfolds as the melting water finds its way under the ice to the ocean. These rivers under the ice still remain as part of the geomorphology of the land and are called eskers.
The esker is one of the most striking landforms of glacial deposition with over thirty identified in Maine. In low-lying, boggy terrain such as the Whalesback area, these snaking ridges dominate the terrain, providing vantage points and dry route ways. Eskers are usually formed of washed sand and gravel. The free-draining ridges are easily quarried, making eskers attractive targets for aggregate extraction, which is what has happened along this section of road in several places. The sediments are usually horizontally- and cross-bedded sands and gravels but vary widely, a reflection of variations in flow regimes and in sediment supply. Eskers are discontinuous because sedimentation may not take place along the entire length of the sub-glacial tunnel. Blocks of the overlying ice may fall into the tunnel. Alternatively, an esker ridge may become segmented by erosion; either by melt water during deglaciation or by the action of post-glacial rivers. The Kadahdin Esker is a 120 miles esker starting near Katahdin and winding its way to the oceans edge at the Pineo Delta just north of Cherryfield.
This earthcache is bringing you on a two-mile long road trip across the top of the esker. As you drive from west to east you will be following the path of the under ice river as it deposited its load of gravel. Along the way you will see gravel pits and the flatlands on either side of the esker from one of the several vantage points. As you drive there is a large bog that will give you some idea of where the base of the esker is located. Most of the trip along this section of the road is very gently rolling making the whole section about the same grade of gravel and the elevation above the base of the esker uniform. It is the same looking to the south but the forest obstructs the view in all but a very few locations. If you look at a road map you will find that route 9 goes west to east from Bangor to Barring with the exception of a few spots. In this location you will find a two-mile stretch of road that travels southeast, the one you will be traveling. If you take the time to look at the map in detail you will discover that the road that travels along the top of the esker is headed toward Cherryfield and Pineo Ridge about 20 miles away. If you follow the same going north you will discover Katahdin about 100 miles away.
Remember this is an earthcache and there is no physical container just an interesting earth science lesson. To log this Earthcache: You must post a photo of you and your GPS some recognizable section of the esker in the background. By posting a photo others will know what you find exciting about the land feature. You must also then send an email your estimate of the average height of the esker. Keep in minded that the bog to both the north and south form the base of the esker and at the beginning and end of your trip you will be driving up to the top of the esker. So at the posted coordinate you will need to measure the elevation change as you drive to the top of the esker. Please include the name of the earthcache in your email. Imagine the force the water must have had to build a land feature like this one.
If you enjoy this earthcache you may want to check the Maine Geological Survey located at (visit link)
They have developed a number of information sheets or field localities giving a great deal of information about geologic features. They also have a number of books and maps about Maine’s natural history/ geology that you might find interesting.
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Treasures
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