Lake Shala is one of a string of Rift Valley lakes in South-Central Ethiopia that lie within the Shala basin, a caldera which probably collapsed about three to four million years ago. About 5,000 to10,000 years ago this area was covered by the large Galla Lake, which was named for the population which now inhabit the area. It is estimated that the current level of Lake Galla was 110 meters above the current level of Lake Shala and incorporated Lakes Shala, Chitu, Abiyatta, Langano and Ziway.
The lake is 28 km long and 12 km wide, with a surface area of 329 square kilometers. It has a maximum depth of 266 meters making it the deepest of Ethiopia's Rift Valley lakes. The lake has no outlet and its water is saline. Lake Shala, along with neighboring Lake Abiyata, is part of Lake Abiyata–Shala National Park, where more than 300 species of birds have been recorded. Lake Shala is surrounded by hot springs, and the earth surrounding the lake is filled with cracks due to erosion and earthquakes.
A spring is where water flows from underground to the surface of the earth. A hot spring is defined as spring where the water temperature is greater than the surrounding air temperature. Water peculates from the surface through underground rocks that are heated from the earth’s mantle. Eventually, the heated water flows into a fault below the surface. As more and more water enters the fault, pressure builds up and the water ascends along the fault line to the surface where it forms a hot spring.
Some hot springs emit Hydrogen Sulphide (H2S) an odor that smells like rotten eggs. H2S is created as anaerobic bacteria converts sulphur from sulphate to the sulphide of H2S. The presence of H2S indicates that the water has penetrated to great depths and been under great pressure, which allows anaerobic bacteria to work. For the water to retain the H2S on its way to the surface, there has to be a large, initial concentration of H2S. The water must either quickly rise to the surface or take a route that does not include oxygen, so the anaerobic bacteria can continue to work and the H2S not be oxidized. If the H2S oxidizes before it reaches the surface there will be no smell.
The posted coordinates take you to a location with several hot springs. The water temperature from these springs is about 97 degrees Celsius.
To get credit for the cache please answer the following:
1) Notice the difference in color of the water in the spring at the posted coordinates and some of the other springs. Why do you think there is a difference in color between the water of these springs?
2) Does the air around the springs have an odor? If there is an odor what does it smell like? What does the presence or lack of an odor indicate about the contents of the water and its likely path to the surface?
3) The water from hot springs can be used for different purposes. What different types of uses do you notice as you walk around the different springs?