And the answer is: mostly plate tectonics, speed of movement, nature of the materials involved. Erosion (and hence climate) play a tiny role but not much
This is why I read ArsTechnica.com and why you should too. Their news reports are written by people actually trained in their field, in this case, by a hydrogeologist. Their reports on public health are written by actual microbiologists and molecular biologists.
Nearly all other “news” sites have these stories written by people with degrees in English literature, journalism, political science, history – any topic other than the science or engineering subject they are writing about.
Blogs, like this one, are written by someone with a background in computer science, software engineering, and an MBA, with additional background in data analysis and modeling, medical informatics, wireless communications and aviation. I often write on subjects that may be outside my area of expertise and you should be completely suspicious of such posts and assume they are written by an idiot. Learn to think for yourself. Oh, and I’ve suffered a half a dozen brain injuries so assume my brain does not work either.