Mineral Waters EarthCache

Mineral Waters Earth Cache

While driving into Hot Springs State Park you will see and read many fascinating signs. The sign that stands before you at the ground zero coordinates will teach you about some of the history and geology of this unique site.

Cliff side view of Big Spring

History:
The Thermopolis hot springs originally were part of the Shoshoni Indian Reservation Treaty of 1868. In the following years the hot springs gained popularity and Congress requested to set this area aside for a National Park Reservation. In 1896 Congress sent James McLaughlin to negotiate a treaty to purchase the Hot Springs with the Indian Chiefs of the area. Chief Washakie of the Shoshoni Tribe and Chief Sharp Nose of the Araphoe Tribe were both in attendance for the treaty signing once agreeable terms were reached. This agreement allowed 'purchase' of the Hot Springs for $60,000 worth of cattle, dry goods and other items.

Geology:
There are several large hot springs near the Wind River Canyon in Hot Springs county that all flow into the Big Horn River, west of this sign. The water originates from an underground flow from the Owl Creek Mountains.

The Thermopolis Hot Springs are one of the largest worldwide and the water flow is over 18,000 gallons/day. The temperature of the hot springs is about 135 degrees (F), but the pools that visitors swim in are regulated to between 102-104 degrees (F) for safety and comfort. To the west one can see the terraces formed over thousands of years by mineral deposits. The mineral deposits are primarily composed of lime and gypsum layers known as travertine. The color of the travertine is influenced by the many species of algae that can be seen thriving in the warm waters here at the park.

Photo: 'Big Springs' to the right of ground zero

The type of hot springs found here at Hot Springs State Park are present due to rain water precipitation that percolates deep into the earth. Once there the water absorbs heat and minerals from the volcanic gases. The super heated mineral dense water is the then returned back up to the surface via pressure and the presence of the Thermopolis Anticline that allows for the perfect conditions to push the water to the surface at this exact spot. As you can see by the sign in front of you many minerals are contained within this water once it returns from deep in the ground.

While visiting Hot Springs State Park there are multiple signs that warn you to take off your silver jewelry before enjoying a swim in the public pools, otherwise the signs state it will 'tarnish' your jewelry. By definition tarnish is a thin layer of corrosion that forms over metals such as copper, brass, aluminum, magnesium and in this case of the warning signs, silver. For silver to tarnish hydrogen sulfide must be present, along with oxygen. Silver will not solely tarnish with oxygen itself. The tarnish will appear as dull, gray or a black film or coating over the metal. Tarnishing performs surface corrosion, as only the top few layers of the metal react. 

The silver spoon on the left has been exposed to hydrogen sulfide and has now tarnished.

In order to log this earth cache, please send the answers to the following questions:

1. Based on the sign in front of you at ground zero, rank in order the top 4 chemical compounds in parts/per million found dissolved in the waters here at the Hot Springs State Park.

2. How does Sulfur contribute to the sights and smells here at the park?

3. To the right of this sign what do you observe from the viewing areas in the water? How does it effect the geology in the area?

4. Which compound found in this water when combined with oxygen will most likely cause tarnishing of your silver jewelry?

5. Along the footpath to your right, there is a sign (N 43°39.29', W 108°11.66') that states the history of these waters. Why were the hot springs so popular and sought after? What did the settlers and Indians believe the heavy mineral content in this water provided for them?