I wanted to create a landscape in which a coastline is lined with a cliff in the following arrangement (the image below is a transversal cross section):
I also wanted this arrangement to be achieved through divergent plate tectonic. Two landmasses would have separated million of years ago, forming a rift. What you see in the image would be one of the halves of the rift.
Another trouble is that I don't want the other landmass to be very near. I want a sizable ocean to be between them. But I don't know if, for that to happen, enough time would have ellapsed for the ocean erosion to destroy the cliffs.
To clarify, this is an earth-like planet. What you are seeing is the coastline of a relatively big continent (more or less the size of Africa). The coastline can be of any size necessary to allow for this arrangement to happen without ceasing to be a coastline.
Could I plausibly achieve through divergent plate tectonics or would I have to find an alternative explanation?