Well written post, especially with the pictures’ context. Being an east coaster I have little experience finding/mapping cliffs. I usually find them around the edges of quarries or earthen banks with severe erosion.
The cliffs here and in @ezekielf ’s example seem a bit extra. I suppose it is valuable to show where one cannot easily walk, but I’d say remove the ones that aren’t dangerous.
RE USGS, you could generate elevation lines with the DEM but I’d only use this to mark cliffs systematically when elevation contours approach a certain density. You could also use it to generate elevation peaks.
