Kentucky River Fault Zone
Stop #3

Dipping Rocks

When a bed of sediment is deposited it is usually large and flat. The alternating light and dark bands on this outcrop represent different layers (beds) in the rock. The beds in this outcrop have obviously been altered in some way since they were deposited. It is kind of difficult to relay how different this area is to everything else around it in this format. But as you travel south on Hwy. 27 out of Lexington or anywhere in this area almoust all of the rocks are perfectly flat, this is not a tectonically active area. The change in the dip of the rocks in the area of stop #3 is dramatic. They go from perfectly flat to what is depicted here in about 20 feet. It looks like the rocks were bent on a hinge. The faults visible along this outcrop are minor features associated with the much larger Kentucky River Fault Zone.

The outcrop in the picture is from the Camp Nelson Limestone of the High Bridge Group, while on the other side of the road the outctop are part of the Lexington Limestone. If you look back at the basemap you will see how the two rock units are directly next to each other on each side of the road, and also that there are some units that should be in between them that are not present. The reason that some of the units here are missing, and why you have older rocks directly next to younger rocks, is becase of a fault, this is one of the major faults in the Kentucky River Fault Zone.

Limestone Cave

In the area of the "hinge" that was mentioned above there is a small cave. All limestone is suceptible to cave formation becuse it dissolves in the presence of acid, and groundwater is slightly acidic. But as always water takes the easiest rout, and since the rock here was already broken up from the deformation, the rock was easier to dissolve.

As you probably know Kentucky is the home of Mammoth Cave National Park, which is about 2 hours ESE of here. Mammoth Cave is one of the largest caves in the world. Around Lexington there are plenty of caves but they are all relativly small. This is becuse around the area of Mammoth the Limestone is very thick, while around Lexinton there are periodic shale and sandstone interbeds. These interbeds prevent the caves from becoming very large becuse they collapse.