Traffic Jam on Ugly Creek Road
Ugly Creek Road is far from the sketchiest byway I’ve navigated in my travels, but it does offer enough soft spots, washouts and creek fords to merit close attention and switching Peggy (my 3/4 ton Ram pickup) into 4 wheel drive.
The key to the geology of Mammoth Cave is that there are two layers of rock beneath these Kentucky hills: a wide belt of limestone capped by a layer of sandstone & shale. The cap rock acts like the lid on a Tupperware bowl, protecting the limestone beneath. Where this cap rock has been compromised in spots, water can make it’s way down to dissolve the limestone layer, forming voids. Since most of the cap rock remains intact, it acts as a roof to protect the limestone from too much erosion, so you end up with caves instead of canyons.