El Vallee Pozos Termales (Hot Springs)
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El Vallee volcano is a broad stratovolcano cut by a large compound Pleistocene caldera, the second largest volcanic crater in the world. The 6 km (4 miles) wide El Vallee de Anton caldera was formed 1.1 to 1.3 million years ago. It has steep, 200 to 300m (650 to 900 ft) high walls overlooking a flat floor underlain by deposits of a former caldera lake and currently occupied by the town of El Vallee, a popular tourist destination 80 km from Panama City. Cerro Pajita, Cerro Gaital, and Cerro Caracoral form a dacitic lava dome complex that was constructed along an E-W-trending lineament within the caldera and forms the 1185m (3887 ft) high point of the volcano.
A geothermal exploration program is currently underway to evaluate the energy potential of the caldera. One example of geothermal activity within the caldera is the town’s “Pozos Termales”, or hot springs.
Hot Springs
A hot spring is a spring that is produced by the emergence of geothermally-heated groundwater from the Earth’s crust. There are hot springs all over the world, on every continent and even under the oceans and seas.
Formation
Most of the rain and snow that falls on the slopes of a mountain or plain ends up in rivers and streams. Some of it, however, filters down (percolates) through the cracks and pores in the Earth’s surface, pulled by gravity to depths of up to 3 kilometers (2 miles) below the surface. It is this water which later returns to the surface in our hot springs.
Springs are defined as places where groundwater is discharged at a specific location. They vary dramatically as to both the amount of water they discharge and the flow rate of the discharge. Some of the water may have traveled great distances underground before resurfacing as a spring. Hot springs are springs having a water temperature that is above average, anywhere from near air temperature up to the boiling point (100 degrees Celsius, 212 degrees Fahrenheit), especially near volcanic areas.
As it descends through the rock, it picks up a variety of minerals by dissolving them in the heated water. When the water gets hot enough it boils, and the resulting pressure forces it upward. The speed at which the water rises, and the degree to which it mixes with cold groundwater, causes the resulting hot springs to have different temperatures.
The water issuing from a hot spring is heated by geothermal heat, i.e., heat from the Earth’s interior. Typically, a hot spring is formed when water percolates into porous sedimentary rocks or fractured volcanic rocks. In general, the temperature of rocks within the Earth increases with depth. The rate of temperature increase with depth is known as the geothermal gradient. If water percolates deeply enough into the crust, it will be heated as it comes into contact with hot rocks. The water from hot springs in non-volcanic areas is heated in this manner.
In volcanic zones such as El Vallee, water may be heated by coming into contact with magma (molten rock). The high temperature gradient near magma may cause water to be heated enough that it boils or becomes superheated. If the water becomes so hot that it builds steam pressure and erupts in a jet above the surface of the Earth, it’s called a geyser. If the water only reaches the surface in the form of steam, it’s called a fumarole. And if the water is mixed with mud and clay, it’s called a mudpot. Hot springs range in flow rates from the tiniest “seeps” to veritable rivers of hot water. El Vallee’s hot springs do not exhibit geysers, fumaroles or mudpots.
Characteristics
Many hot springs have a sulfur smell. Anaerobic bacteria living deep beneath the Earth’s crust convert the dissolved sulfur in the water into hydrogen sulfide, imparting a “rotten eggs” odor. El Vallee’s water does not smell of sulfur, either due to the water not reaching sufficient depths, or the water on its return to the surface being oxidized and losing its hydrogen sulfide. It could also be a reflection of the type of rock found in the area, as pyrite and gypsum, two common sulfur-bearing minerals, are not found in sufficient amounts.
As the hot springs water bubbles from its underground source onto the surface, it begins to precipitate out the minerals it gained on its travels through the ground. One of the common minerals is calcium carbonate, which hardens into a porous grey-brown rock called tufa, usually seen encircling the hot springs. At El Vallee the hot springs water is piped into concrete pools, but you can still see evidence of tufa on the ground beneath the free flowing taps.
Therapeutic Uses
Because heated water can hold more dissolved solids than cooler water, warm and especially hot springs often have very high mineral content, containing everything from simple calcium to lithium, and even radium (not present in El Vallee). Because of both the folklore and the claimed medical value some of these springs have, they are often popular tourist destinations, and locations for rehabilitation clinics for those with disabilities. El Vallee hot springs offer two therapeutic mud treatments in conjunction with its 5 pools of high-mineral-content waters.
Hazards
Some hot springs may be so hot as to produce thermal burns, whereas most hot springs can cause dehydration, hypotension (low blood pressure), and heat exhaustion with prolonged exposure. Individuals with health problems and taking certain medications may be at a higher risk for potential ill effects of hyperthermia (increased core body temperature) when using these facilities. Hot springs also create ideal conditions to spread infections by promoting algae, amoeba and bacterial growth.
The El Vallee hot springs have an entrance fee of $3.00 US (which includes a free therapeutic mud treatment for first-time visitors) and there are limited hours of access to the facilities (0800 to 1700 hours daily).
To claim this EarthCache you must
1. Take and post a photo of you and your GPSr at either the hot spring’s sign or one of the pools and e-mail me the answers to the following questions:
2. What is the average temperature of the hot spring?
3. What is/are the predominant mineral(s) of the hot spring? (this can be found on a sign near the entrance)
4. Name one specific infection that can be spread through hot springs.
Do not post your answers, encrypted or otherwise, on your log.
DO NOT LOG AS A FIND UNTIL YOU HAVE A PICTURE READY TO POST AT THE TIME OF LOGGING A FIND FOR THIS EC. Logs with no photo of the actual cacher logging the find or failure to answer required questions through e-mail will result in a log deletion without notice. Exceptions will be considered if you contact me first.
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