The first three links above outline the general aspects of karst features for those who may be new to caving, and includes quite a few examples and diagrams, from both here in the hills and elsewhere. The next two links go on to surmise my current thoughts on Black Hills area caves and their speleogenesis while the last link deals with the geochemical aspects of cave formation. There is a lot more science and opinion in the last three links, but that is a natural consequence of my background, many years of observations and the countless discussions I've shared with so many like-minded and observant souls.
No apologizes for the opinions, as I hold that I come by them honestly. We should each openly embrace the freedom to question and challenge...that's what science, learning and the pursuit of knowledge are all about. Push the envelope or you'll never get out of the bubble of complacency.
“Consider your origin. You were not formed to live like brutes but to follow virtue and knowledge.” ― Dante Alighieri, The Divine Comedy