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IARGO SPRINGS:
This interpretive site in the Huron-Manistee National Forest hides
one of the most beautiful natural springs. It has several different
levels with breathtaking views, especially the top deck which juts
out over a 200 foot drop to the edge of Cooke Dam Pond. There is a
wooden boardwalk with over 300 steps leading you down to the
springs. On the way down, you can stop at different levels and
enjoy the view through the pine, cedar, hemlock, and old-growth
hardwood trees. It is open year-round, and our last visit was
preceded 4 days prior by a late winter storm and five-plus inches
of snow, making the deck snow-covered and slippery.
SPRING FORMATION:
A spring is a natural resurgence of groundwater, often alongside a
natural slope or valley floor. There are several different natural
means and processes that can form a spring. The formation of a
natural spring begins with a water source, usually rain or snow, or
sometimes a river. It percolates and flows downward through porous
material, such as soil and sedimentary rock. Hot, or thermal,
springs usually form when this water flows deep enough into the
earth to heat it, then encounters a crack or thrust fault which the
underground water follows. As the water builds up behind it, the
pressure of the now heated water rises and can force the water flow
upward to the surface. The temperature of the spring water is
dependant on how deep it flowed into the Earth and was thusly
exposed to the primordial heat of the Earth, and how quickly it
exited. Hot mineral springs would have the added feature of
possessing a minimum of 400 parts per million of total dissolved
solids. This occurs quite often when the underground water flows
through limestone or dolomite (a limestone-magnesium mix).
Another type of spring formation is through what is known as karst
topography. This is when acidic rain water dissolves some types of
soluble rock over a period of many thousands of years, creating
underground streams and caverns. Characteristics of karst
topography include the presence of active underground water
aquifers, the lack of surface waterflows, and the presence of
caves, sinkholes, and large springs. About twenty percent of the
ground surface in the USA is typical karst topography, and it
provides about one-fourth of the total drinking water sources in
the USA via its underground rivers.
The method of spring formation at Iargo (not Largo) is similar to
how hot springs are formed, but with important differences. The
surface water flows downward until it meets a naturally impervious
layer, such as clay. The water flows along the surface of the clay,
with the water behind it pushing it. It finds an exit, creating the
spring effect. The larger the area of watershed and the larger the
amount of recent precipitation, the greater the spring flow. At
Iargo Springs, this water feeds the Au Sable River, flowing first
into Cooke Dam Pond. The sediment from the spring water drops as
the water flow rate decreases, depositing sediment which creates an
area much like a delta, where the spring water meets the larger
pond. An aerial depiction on one of the sign boards clearly shows
this sedimentary area, as well as the continuation of the water
flow as it makes its way through the ponds and retention areas and
into the Au Sable River.
LOGGING REQUIREMENTS:
To log this EarthCache, you must gather three pieces of
information. You will need two items: a clean container to collect
a water sample (no glass please), and some type of thermometer to
take a water temperature reading down to just above freezing. A
thermometer used to take human body temperature isn't going to
work.
===> 1: It is required that you go to Iargo Springs and
descend the stairway to the bottom and actually view the natural
springs. Once there, you should stand on the boardwalk where the
springs flows under it, and take a water sample with your clean
container. Take the water temperature and make note of it.
===> 2: Then you put your nose to the test. Place the
sample cup near your nose and move your hand over the cup and waft
any odor to your nose. Do not get any of this water on your face or
into your eyes or nose! Read the three interpretive sign boards in
this area, one of which advises why you don’t want to do that.
Smell the water and advise how you would characterize what you
smell. Some examples would be musky, fishy, algae, sulphur, fresh
(no smell), nitrates (fertilizer smell), ammonia, chlorine,
minerals, and so on.
===> 3: The third requirement is to locate the
interpretive sign board near the springs that has drawings and
names of the various wildflowers in the area. What is the name of
the wildflower in the middle of the bottom row? It’s name starts
with a color.
Email me with your findings regarding the water temperature and
odor, and the name of the correct wildflower. Do not post any
answers in your log, even encrypted. If you claim a "find" on
this EarthCache and do not email me with the required answers, I
must delete your log. If your answers are in error, I will ask
you to explain them before I delete the log. I *REALLY* dislike
deleting logs (have only had to do it with this EarthCache), so I
made the requirements for this one easy for those that were
actually at the site.
LETS HELP MOTHER NATURE ….AND OURSELVES:
Permission to establish this EarthCache was obtained from the
National Forest Service. As a condition of granting this
permission, they require certain criteria must be met at all times.
These criteria include, but are not limited to, the following: Do
not abandon or leave items at the site, or take physical items
away. Stay on designated walkways (the boardwalk). Do not disturb
any cultural resource, soil, plants, animals, or other visitors to
the site. Follow the “No Trace” principles.
Now you get to climb back up those stairs……
Additional Hints
(No hints available.)