Pigeon River Artesian Well EarthCache
Pigeon River Artesian Well
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This EarthCache is located at the Pigeon River Campground in the heart of Michigan's Elk Country. The Pigeon River State Forest offers many recreational opportunities for families and individuals alike.
The United States Geological Survey (USGS) defines an aquifer as a geologic formation, group of formations, or part of a formation that contains sufficient saturated, permeable material to yield significant quantities of water to wells and springs. An aquifer, also, is capable of holding and transmitting large quantities of water
The water in an artesian well flows from an aquifer. Artesian wells are deep-drilled wells through which water is forced upward under pressure. Artesian springs can occur in similar fashion where faults or cracks in the overlying impervious layer allow water to flow upward. Water from an artesian well or spring is usually cold and free of organic contaminants so it is desirable for drinking.
The geologic conditions necessary for an artesian well are an inclined aquifer sandwiched between rock layers above and below that trap water in it. Water enters the exposed edge of the aquifer at a high elevation and flow downward through the connected pore spaces. The water held in these spaces is under pressure because of its own in the portion of the aquifer above itself. If a well is drilled from the surface through the overlying impermeable layer into the aquifer, the pressure will cause the water to rise in the well. In areas where the slope of the aquifer is great enough, pressure will drive the water above ground level in a spectacular, ever-flowing fountain.
The area these aquifers cover can be monumental. In North America, the Dakota sandstone provides aquifers for an artesian system that underlies parts of the Dakotas, Montana, Wyoming, Kansas, Nebraska, and Saskatchewan and supplies great quantities of water to the dry Great Plains region. Many East Coast cities derive their water supplies from aquifers that are exposed along the edge of the Piedmont and dip downward toward the Atlantic coast. The largest artesian system in the world underlies nearly all of Eastern and Southern Australia. Other important artesian systems serve London, Paris, and East Algeria.
According to the USGS all or part of five aquifers are located in Michigan. The aquifer is named for the upper most principal aquifer and classified as one of six types of permeable geologic material: unconsolidated deposits of sand and gravel, semiconsolidated sand, sandstone, carbonate rocks, interbedded sandstone and carbonate rocks, or basalt and other types of volcanic rock.
The five aquifers in Michigan are the Jacobsville; the Cambrian-Ordovician; the Marshall; the Pennsylvanian; and the Silurian-Devonian. All of the aquifers are classified as sandstone aquifers with the exception of the Silurian-Devonian. The Silurian-Devonian is classified as a carbonate-rock aquifer. The thickness of the carbonate rocks that compose most of the Silurian-Devonian aquifer average about 300 to 400 feet. In these carbonate rocks the water movement is mainly through secondary openings such as joints and fractures. Many of these opening have been enlarged by dissolution which, in northern part of the Lower Peninsula of Michigan, has resulted in extensive areas of karst features such as sinkholes and caves.
In review, for an artesian system to develop, three geologic conditions must be present.
1. The aquifer must be confined above and below to prevent water from escaping.
2. The rock formation is usually tilted and exposed at the surface, enabling the aquifer to be recharged.
3. There is sufficient precipitation in the recharge zone to keep the aquifer filled.
An artesian well will flow freely at the ground surface only if the wellhead is at an elevation below the artesian pressure surface. In this situation, the water flows out of the well because it rises toward the artesian-pressure surface which is at a higher elevation than the wellhead.
To log this EarthCache you must meet the following requirements:
1. Post a picture of yourself and your GPS at this Artesian well.
2. Email me your estimate of the rate, gallons per minute, at which the well is pumping out water. This can be done by bringing a one gallon bucket, and a watch with a second hand. Then, you simply time how long it takes to fill the one gallon bucket. Use the formula to calculate gallons per minute.
1 gal. / __ sec. multiplied by 60 sec. / 1 min.
CONGRATULATIONS TO TREEPLANTER ON THE FTF!!
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