Karst topography means a landscape that has underlying limestone as its bedrock where caves, sinkholes, underground rivers, and springs can form. You’ve heard of Mammoth Cave, right? Well, that national park and thousands of other limestone caves around the country we formed because they were located in karst topography. These karst areas also often have direct pathways from the surface down into groundwater aquifers because of how easily water passes through dissolved cracks and channels in the limestone. And why does water pass so easily through this limestone?
It all begins in the clouds. Raindrops that fall from the sky pick up carbon molecules from carbon dioxide in the air as they plummet toward the ground. This combination creates a weak acid known as carbonic acid. Limestone (CaCO3) is a weak base so it reacts with carbonic acid and begins to dissolve along tiny fractures in the rock. Over time, and we’re talking over thousands of years, these cracks get wider to the point where they can actually form massive caves. Mammoth Cave, in Kentucky, is one 400 mile-long example. You can imagine how these caves are underground highways for water. And many of these underground waterways also serve as aquifers for drinking water.
Watch the video to learn more about these methods plus use the classroom lesson activities to learn the skinny on karst non-point source pollution in your region. To "spelunker" you way deeper in the hidden world of karst topography and its environmental implications:
Also, find out more about what you can do to keep your local waters healthy and clean by checking out the website of our educational partner, Wisconsin Land+Water.