Stone's Spring Earthcache EarthCache
Stone's Spring Earthcache
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During the United State's last glacial period, around 20,000 years ago, a massive glacier known as the Laurentide Ice Sheet continually moved up and down, expanding and retracting, through what would become the State of Illinois. The grinding effects of the glacier left most of the Midwest, including nearly all of Illinois, as flat as a pancake. The glacier stretched as far south as St. Louis, MO, leaving everything to the north flat, while everything to the south remained untouched and geologically intact.
All of that water that melted off of the glacier during its periods of expansion and recession carved some remarkable geological features in the sandstone bedrock, leaving behind enormous canyons, cliff faces, and bizarre rock formations, many of which have been designated as National Natural Landmarks.
How Does a Spring Form?
A spring is formed when the side of a hill or some other excavation crosses flowing ground water which is at or below the water table. A spring results from an aquifer filled to the point that the water overflows onto the surface. The springs may range in size from small seeps that flow occasionally after a large rainfall to huge pools pouring forth hundreds of millions of gallons daily.
Springs form in rock. Some of the largest springs are formed in limestone and dolomite. Both dolomite and limestone fracture or crack relatively easily. Rainwater seeps through the ground undergoing a chemical change forming a weak carbonic acid which then enters these cracks and dissolves the rock. When the water reaches a horizontal crack or a layer of non-dissolving rock such as sandstone or shale, it begins to move sideways, forming an underground stream. Eventually this can form a large opening, or cave and may take tens to hundreds of thousands of years to complete.
The intake/recharge area of the aquifer at Shawnee National Forest sits at a higher elevation than the rest of the aquifer. The rest of the rock foundation housing the aquifer dips downward, causing the water to move downhill and away from the intake area, gradually building up pressure. This build-up of pressure is in the confined aquifer is what causes the water to rise to the surface. When a well is drilled, the pressure is reduced, and the water is forced upward. An artesian spring occurs where there is a fault or fracture in the rock confining the aquifer. Just like a well, these fractures reduce the built-up pressure and force the water to the surface.
How Much Water Flows?
The amount of water that flows from springs depends on many things. The size of the caverns in the rock, the water pressure of the aquifer, the size of the spring basin, and the amount of rainfall. Human activities also influence the amount of water that comes from a spring. Groundwater withdrawals in an area can reduce the pressure and water levels in an aquifer, decreasing the flow from the spring.
Is the Water Hot or Cold?
The temperature of the water depends on the temperature of the rocks it is passing through, and how long it travels before surfacing. For example, the temperature of an Ozark spring comes from its passing through rock at an average temperature of 56 F. But on the other hand, thermal springs, such as in the bubbling mud springs in Yellowstone National Park, Wyoming, occur in regions of recent volcanic activity and are fed by water heated by contact with hot rocks far below the surface.
Logging Requirements
In order to log this cache, determine the following and email me the answer. DO NOT post your answer in your log.
1.Determine the flow rate of the spring in the SI unit (cubic meters per second)
2. The temperature of the spring water at the time of your visit
3. This is not a requirement but would be appreciated that you post a picture of yourself/group with your GPSr near the fountain.
As with all other caches please be considerate of the surroundings. Please do not bother any of the landscaping and please be careful when pulling off and onto the highway.
Additional Hints
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Treasures
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