All lakes fill bowl-shaped depressions in the Earth's surface, called basins. Lake basins are formed in several ways. Many lakes, especially those in the Northern Hemisphere, were formed by glaciers that covered large areas of land during the most recent ice age, about 18,000 years ago. Though early Shady Lake fell into this category, there are some more unique details both before and after the dam was put in place. As is the case with most of western Arkansas and Eastern Oklahoma, this area was forced mostly by the Glaciers of the Ice Age and later the Ouachita Basin. As Glaciers pushed rocks, soil, and debris southward, the Ouachita Mountains were formed. Eventually the glaciers receded, leaving behind the deposits of earth which were submerged in the newly formed Ouachita Basin. All this lead to the mountains being built up, so that once the water itself began to recede, and allow for the erosion that is still happening today, to form the mountains we see today. It was in this final process that the early and somewhat smaller Shady Lake was initially formed. The ridges, which remain unnamed, stem from Tall Peak. These ridges trapped a portion of the water flowing out from Tall Peak. The creek that feeds the lake comes out of the rocks from Tall Peak and flows down into the basin that forms the Lake. This feature was further harnessed by the CCC in 1937 with the addition of a 26 foot spillway that greatly increased the size of the lake. Another unique feature of this lake is the water itself. Most people already know about the Hot Springs of the Ouachita's, but that is information for another earthcache. Here in the higher elevations, the same mineral water has been allowed to cool, but due to pressure has been pushed up and out through the sandstone. The now cool water flows down from the mountain and into the lake where the minerals promote the growth of blue green algae and lend to the lakes hue. In an are of the country where most water is at best clear but usually murky or even brackish, this lake is very unusual to have such a color.
To Log this Cache
1. Tell me the elevation you see on your GPS.
2. What other effects have the spillway had on the lake other than expanding it?
3. Based on the information above, what do you think is causing the pressure that pushes the water up and out of Tall Peak which feeds the lake?
4. the creek the feeds the lake comes in from the North side. What is the creekbed like? Silty, rocky, or sandy?
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