Derby season is in full swing here in Louisville! Residents are busy enjoying the festival activities and are preparing for the flood of visitors into the city for the Kentucky Derby Race on Saturday! As a transplant to Louisville, I have many questions each year around Derby time and this year I have been learning about why so many of the strongest and fastest thoroughbred horses come from just a few hours away from Churchill Downs. It turns out that the unique geology of Kentucky provides ideal conditions for raising horses!
According to the Kentucky Geological Survey website, over fifty percent of the surface rocks in Kentucky are limestone. Most limestone is formed in warm, calm, shallow, marine environments. Kentucky’s limestone is very flat, sedimentary rock that is primarily made of the mineral calcite, or calcium carbonate. When horses graze on pastures grown on limestone, they consume calcium carbonate which helps harden their bones, just as milk does for humans.
Raising thoroughbreds on limestone pastures has proved extremely beneficial through the years- we’ll see how our Kentucky-raised thoroughbreds do this weekend at the races!
The limestone geology in Kentucky has also provided the ideal conditions for distilling bourbon and for the formation of Kentucky’s many large caves and waterfalls. During the Paleozoic era (540-248 million years ago), Jefferson County was covered by a shallow sea and was home to many marine invertebrates. While the continents have shifted since then, creating mountains and oceans, Kentucky has remained fairly stable. Because of this, we can find very flat, stacked sedimentary layers of limestone, shale, and dolomite throughout The Parklands.
While you’re hiking through Distillery Bend, you can see the limestone bedrock around the Flats Picnic Grove and Trail. As you hike along the Sycamore Trail and gravel bars, you will find brachiopod fossils in the majority of limestone rocks along the creek bed. The brachiopods lived during the Ordovician period between 443 and 490 million years ago and were the most common species at that time. It’s amazing to see how the land has evolved since the Paleozoic era and to watch it continue to change as the land is preserved as a natural park.
Story by Rachel Brunner, Interpretive Ranger for The Parklands of Floyds Fork