The Earthcache is located within the Yellowbank WMA. It is open to the public with its hiking trails, fishing, horseback riding and also hunting. With the last in particular geocacher should wear orange to protect himself or herself during the hunting season. The land formation of the Yellowbank WMA came about as follows. In Breckinridge County from consoldiated sedimentary rocks of Mississippian through Pennsylvanian age and from unconsolidated sediments of Quarternary age. Geologists call the oldest rocks found at the surface in Breckinridge County The St. Louis Limestone. The most common rock types in Yellowbank WMA are Mississippian limestones, which were deposited 350 million years ago in the bottom of a warm, shallow sea. At the end of the Mississippian Period, 320 million years ago, the seas receded and sediments of the Pennsylvanian were deposited. What this means that Kentucky and has limestone underneath our surface. All of the counties at least 90 of 120 has karst terrian. This can be found with the Mammoth Cave System, which runs 350 miles.
A karst landscape has sinkholes, sinking streams, caves, springs. In Yellowbank, I have seen the sinkholes, heard the flowing water inside the sinkhole and discharge at the end of the spring. How they develop most commonly on limestone and are formed many years. As water runs underground, from hilltop toward a stream through tiny fractures in the limestone bedrock, the rock is slowly dissolved away by weak acids found naturally in rain and soil.
Spring
An aquifer is any body of rock from which important quantities of drinkable water may be produced. Springs are sites where groundwater emerges from an aquifer to become surface water. Springs occur along creeks and rivers where the water table meets the land surface. They also occur where rocks that do not allow water to flow easily, such as shale, underlie or have been faulted against permeable rock. The impermeable rock blocks the groundwater, forcing it to the surface. Karst springs occur where the groundwater flow has concentrated to dissolve a conduit or cave in soluble rock. The groundwater basin of karst spring collects drainage from all the sinkholes and sinking streams it its draining area. The water flowing from each sinkhole joins together underground to form ever-increasing flow in successively larger passages, which discharge at the spring. Karst springs can have large openings and discharge very large volumes of water. The soil cover, narrow fractures, small conduits, and larger cave passages. But I came upon small openings here Yellowbank and small flow of water. But if a lot of water can be lot of volume of water.
Sinkholes
A sinkhole is any depression in the surface of the ground into which rainfall is drained. Karst sinkholes form when a fracture in the limestone bedrock is enlarged. Sinkholes form in two ways. In the first way, the bedrock roof of the cave becomes too thin to support the weight of the bedrock and soil material above it. The cave roof then collapses, forming a collapse sinkhole. Bedrock collapse is rare, and the least likely way a sinkhole can form, although it is commonly assumed to form all sinkholes. The second way sinkholes form is much more common and much less dramatic. As the rock is dissolved and carried away underground, the soil gently slumps or erodes into a dissolution sinkhole. Once the underlying conduits become large enough, insoluble soil and rock particles are carried away too. Dissolution sinkholes form over long periods of time.
All of the dissolved limestone and soil particles eroded from the bedrock to form a sinkhole pass through the sinkhole's throat. The throat of a sinkhole is sometimes visible, but is commonly roofed by soil and broken rock and can be partly or completely filled with rubble. This opening can vary from few inches in diameter to many feet. Water flows out of the sinkhole throat to a conduit that drains to a spring.
A karst window is a special type of sinkhole that gives us view, or window, into the karst aquifer. A karst window has spring on one end, surface-flowing stream across its bottom, and swallow hole at the other end. The stream is typically at the top of the water table. Karst windows develop by both dissolution and collapse of the bedrock. Many karst windows originated as collapse sinkholes.
I hope this information about sinkholes gives some insight on the making and destructed power of a sinkhole.
Questions and answers of the lesson.
1. At the sinkhole, how deep and wide is the sinkhole.
2. As the spring flows from the sinkholes and flows down the stream. What creek does it empty into and river.
3. What type of sinkhole is here. Why.
Optional- a pic of yourself at the sinkhole.
