Designing landscapes is difficult, because we often don't take into account the geological processes that formed them in the first place. You wouldn't have a ten-mile-high mountain on Earth, because the tectonic plates never produced enough force in their interactions to create such a large mass of rock. Neither would you really have a river with massive waterfalls every mile until it reaches the sea, because the likelihood is that the land would flatten long before it reached the sea and more waterfalls would just take it underground.
So, taking into account the geology of landscapes, how can I go about designing a realistic landscape? I'm looking for things like
- relative locations
along with reasoning of why these things would be the way they are.