Osage Cuestas
January 03, 2010
Greenwood County is located on the boundary between the Flint Hills region of Kansas and the Osage Cuestas region. Cuesta is a Spanish word for cliff. This region is characterized by a series of escarpments that face east. A rock escarpment is a feature located in the outdoor classroom at our school. It faces east as well and has a gently inclined surface that slopes to the west. The Pennsylvanian age limestones and shales found in the topography of this region dip gently to west and northwest.
While learning about the topography of Cuestas, students made a model by alternating hard and soft rock layers in a plastic container. The layers represent the limestone and shales that were deposited in shallow seas that covered this area about 300 million years ago. Fossils can be found in these escarpments as evidence of the abundant life that was found in the seas at that time. The limestone is a sedimentary rock made mostly of calcite found in the shells or skeletons from this marine life. Shale is a sedimentary rock as well, but is made of compacted clay.
The students arranged the layers to slope to one side of the model. Blue food coloring was then added to represent a surface pollutant and a spray bottle represented the rain that would send the pollutant into the soil. As you can see from the model, the pollutant can travel a long way along the layers of limestone. In the model where the rock layers were flat, the food coloring did not move as far from the source of pollution.
Students are learning about water quality. Groundwater is a water source that is part of the small percentage of fresh water available for consumption on earth. Students are still problem solving on how to remove the food coloring from the ground so it does not further affect the water in the water table.
