Another cliché idea is the chasm, including chasms with bridges over them. I'm not so sure how common a broken bridge is, though; naturally, I just had to make one of my own. This bridge is a slightly exotic-looking one lined with stone pillars bent inwards at the tip, sort of like a horn (and reminiscent of the horn pillars I used in a previous geomorph for a stone circle.) I applied a gradient to the bottom of the chasm, just to make it stand out, but the chasm can pretty much be any depth you need. It crosses the geomorph diagonally and prevents crossing from one side to the opposite side.
I happen to be kind of proud of this bridge model that I made specifically for this geomorph.