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Haystack Mountain EarthCache

Hidden : 09/02/2009
3.5 out of 5
3.5 out of 5

Size: Size:   not chosen (not chosen)

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Geocache Description:

This earthcache will give you an understanding of Haystack Mountain, which is a true Aroostook County landmark.

Central Aroostook County is characterized by gently rolling hills to the east along the border with New Brunswick, Canada, while the topography to the west is more elevated and rugged. This difference in landscape can be attributed in a general way to the underlying geology. The eastern region is underlain by more easily eroded limestone and calcareous shale, while more resistant sedimentary and volcanic rocks underlie the western region. But within the eastern region you will find Haystack Mountain.

Haystack Mountain is located in the town of Castle Hill approximately ten miles west of Presque Isle. At an elevation of 1,142 feet (348 meters) Haystack Mountain offers a 360-degree view of the surrounding countryside. The 215-acre property is leased to the Town of Castle Hill by the Maine Department of Conservation, Bureau of Parks and Lands which can be accessed by a right turn off Maine Route 163, at the crest of a hill about four miles west of Mapleton. Here you will find a gravel parking lot. The hike up Haystack Mountain is a moderate hike, approximately a one-third of a mile of very steep mile trail.

Rocks exposed at the summit of Haystack Mountain are felsic volcanic rocks of the Winterville Formation. The Winterville Formation is a widespread unit of sedimentary and volcanic rocks of Late Ordovician age. It is believed that these rocks have been deposited by deep-water, submarine sedimentation and volcanism. Later mountain-building events and erosion through geologic time have left a complicated pattern of surface exposure at the summit. Haystack Mountain is within a narrow belt of the Winterville Formation that is approximately a mile across and over five miles long, extending from Haystack and Pyle Mountains northward to Castle Hill. This belt is in the core of a large fold, the Castle Hill anticline (seen to the east), which is convex upward, bringing the older rocks to the surface. The oldest rocks, of the Winterville Formation, are exposed in the center of the fold, overlain in turn by the Late Ordovician Pyle Mountain Argillite, and then by rocks of Silurian age on the flanks of the fold.

The rock exposed on Haystack Mountain is rhyolite, one of the volcanic rock types of the Winterville Formation. It is a light-colored rock composed predominantly of fine-grained feldspar. In places, it contains coarser mineral grains in a porphyritic texture. Because of its fine-grained crystalline texture, it is difficult to break and resists erosion. This is why Haystack Mountain stands above the surrounding landscape. The age of these felsic volcanic rocks is not known precisely, but fossils from just below the overlying Pyle Mountain Argillite to the east imply that the Winterville Formation in the Castle Hill area dates to the Caradocian stage of the Late Ordovician, approximately 450 to 460 million years ago.

The posted coordinates will bring you to the summit of Haystack Mountain.. Remember this is an earthcache, so there is no container - just an earth science lesson at a beautiful natural feature. To log this cache, you must post a photo of yourself or your hand with your GPS showing a summit view in the background. As you hike up you should be able to see the difference in the structure of the rocks, by the way it has broken or fractured. Email me through my profile the difference between the rocks formed on the side slopes and the rocks found at the summit. Please include the name of the earthcache and the number of people in your group in your email. Please take the time to describe why you find this location special so that others might have the same experience.

Please remember that this park is maintained by Maine Department of Conservation - Bureau of Parks and Lands for the general public. So please make sure to follow all regulations carefully as hike. Remember that forethought and a little preparation are the key elements to a successful and enjoyable outdoor experience. Do not leave the trail and make sure to practice "Carry-in-carry out" to keep this area special for the future visitors.

"The Bedrock Geology of Mount Battie, Camden" webpage by the Maine Geological Survey at (visit link) was used as the primary source of information.

The Maine Geological Survey reference page "The Geology of Haystack Mountain, Castle Hill, Maine" (visit link) was the source for this earthcache.

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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