The Bubble EarthCache
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Boiling Springs is named after the spring network across a two acre segment of the city.
At the coordinates, you can view one of the most prominent of the springs. The location is also a very enjoyable spot for a visit.
There are thirty springs within the two acres and they produce 22 Million gallons of water per day that reach the surface. Imagine that amount of water moving beneath your feet!
Some Technical Information:
The key geological aspects of the spring at your coordinates are:
(1) Diabase
(2) Dikes
(3) Limestone
(4) Hydrogeology
Hydrogeology is the scientific study of Water (hydro) and Earth (geology).
Diabase is igneous rock. Igneous rock is formed by subterranean (beneath the surface) magma that intrudes (pushes up through) existing rock.
Limestone is sedimentary rock, usually made up of various minerals and organisms (dead or alive).
Dikes are basalt rock intruding limestone that form a subterranean structure (in this case a V structure).
Our Focus:
The dikes were formed during the late Triassic/early Jurassic (200 million years ago). You've more than likely heard that Africa and North America collided and then separated during that period.
As they separated, magma was generated via decompression and melting and the molten rock intruded into the subterranean faults. Because of the cooling just below the surface, the subterranean fill created solid thin sheets of basalt (the diabase).
The diabase dikes (sheets in a V) are located directly beneath Boiling Springs. The thirty springs produce the water that makes up the seven acre lake nearby. Note the R0 waypoint for viewing the lake and related information boards about the area. The lake, built in the early 1800s to support an iron production facility downstream, is supplied by nearly 11,500 gallons per minute from the springs.
Analysis provided in a Geological Society of America article indicates that additional sources of heat and discharge force may be present near South Mountain to the South of the springs. Water from that location may move much deeper underground through quarzite to reach the spring areas.
Look at the pool at the coordinates. This pool is known locally as the Bubble. You can see the "boiling" effect created as water flows locally from streams 1800 feet below to about 45 feet below ground into the V of the dike border. The water trapped in the barrier of the dike creates pressure that forces the water to the surface and out into the springs.
The final interesting geological aspect of the Bubble is that the water remains at 52-53 degrees F year round. The temperature is caused by the continuous pressure below surface, not by underground heat sources.
Questions:
(1) What is the height of the water (inches above surface) at the Bubble? It varies hour by hour.
(2) Given the discussion, how long do you think the Bubble will continue to produce the temperate water?
(3) In your opinion, what would the area look like had the city not created the lake that then feeds into Yellow Breeches Creek?
Please Email your responses to either Cache Owner to secure your Smiley?
Permission: Cumberland County GIS (for South Middleton Township and Boiling Springs).
Additional Hints
(No hints available.)