So, for an area of my world, I'm imagining three cities situated along the stretch of a river, running from a lake in the mountains onto relatively flat terrain (though still a bit above sea level) and finally emptying into the ocean via a series of waterfalls cascading over fairly steep cliffs. One of the cities is to be located close to these waterfalls, clinging to the surrounding cliffs and also spreading back inland. I'm also imagining the cliffs to be containing plenty of sea caves, some of which connect with larger cave systems inland.
Would this kind of arrangment be plausible, or would a geologist laugh at reading this description of the landscape? If it's off, what would need to change to make it more realistic? The orientation of the mountains, river and coast (i.e. which direction the river flows in, etc.), as well as the rock types of the area, are things I've deliberately not decided yet, as they don't matter much for me, and I'd be happy to adapt them to whatever makes the coast + river scenario the most plausible.