Benson's Flowing Well. EarthCache
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Difficulty:
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Terrain:
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Size: 
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ARTESIAN
SPRINGS
Water issuing from an artesian spring rises to
a higher elevation than the top of the confined aquifer from which
it issues. When water issues from the ground it may form into a
pool or flow downhill, in surface streams. Sometimes a spring is
termed a seep. Minerals become dissolved in the water as it moves
through the underground rocks. This may give the water flavor and
even carbon dioxide bubbles, depending upon the nature of the
geology through which it passes.
Mineral water is water containing minerals or
other dissolved substances that alter its taste or give it
therapeutic value. Salts, sulfur compounds, and gases are among the
substances that can be dissolved in the water. Mineral water can
often be effervescent. Mineral water can be prepared or can occur
naturally.
Springs may be formed in any sort of rock.
Small ones are found in many places. In Iowa, the largest springs
are formed in limestone and dolomite in the karst topography of The
Driftless Area . This area is characterized by caves and cave
systems, disappearing streams, blind valleys, underground streams,
sinkholes, springs, and cold streams. Disappearing streams occur
where surface waters sinks down into the earth through fractured
bedrock or a sinkhole, either joining an aquifer, or becoming an
underground stream. Blind valleys are formed by disappearing
streams and lack an outlet to any other stream. Sinkholes are the
result of the collapse of the roof of a cave, and surface water can
flow directly into them. Disappearing streams can re-emerge as
large cold springs. Cold streams with cold springs as it sources
are noted as superb trout habitat.
Both dolomite and limestone fracture relatively
easily. When weak carbonic acid (formed by rainwater percolating
through organic matter in the soil) enters these fractures it
dissolves bedrock. When it reaches a horizontal crack or a layer of
non-dissolving rock such as sandstone or shale, it begins to cut
sideways, forming an underground stream. As the process continues,
the water hollows out more rock, eventually admitting an airspace,
at which point the spring stream can be considered a cave. This
process is supposed to take tens to hundreds of thousands of years
to complete.
Springs are often classified by the volume of
the water they discharge. The largest springs are called
"first-magnitude".
Spring
flow scale
Magnitude
Flow (ft³/s,L/s)
1st Magnitude > 100 ft³/s 2800
L/s
2nd Magnitude 10 to 100 ft³/s 280 to
2800 L/s
3rd Magnitude 1 to 10 ft³/s 28 to 280
L/s
4th Magnitude 100 US gal/min to 1 ft³/s
(448 US gal/min) 6.3 to 28 L/s
5th Magnitude 10 to 100 gal/min 0.63 to
6.3 L/s
6th Magnitude 1 to 10 gal/min 63 to 630
mL/s
7th Magnitude 1 pint to 1 gal/min 8 to
63 mL/s
8th Magnitude Less than 1 pint/min 8
mL/s
0 Magnitude no flow (sites of
past/historic flow)
To log
this EarthCache, email me the answers the following
questions:
1. Take a large mouth one litre
container and fill it at the springs. Use a stop watch or your
regular watch to time the amount of time it takes to fill the litre
container.What is the number of litres per second coming from this
spring?
2. What is the magnitude of this spring
according to the scale above?
3. What is the temperature of the
water?
4. Photos are fun and further proof that
you have actually been to this spring site.
If you would
like, please upload a photo of you and/or your group with a GPS
at the above coordinates and the springs in the background.
(See example below)
Additional Hints
(No hints available.)