LOL! Check out Mother Nature at work:
"PAMUKKALE is one of the most unique phenomenon in nature"
www.millionface.com/l/pamukkale-is-one-of-the-most-unique-phenomena-in-nature/
I wouldn't say that, it's just strata and outcrop with puddles, that's all. Still natural, just weird, there's a pyroclastic cloud that calico posted a little while ago with a massive electrical storm raging on the surface, if I saw that in terragen then I would think it's freakin awesome but unnatural.
Matrix, I agree. Many of us have commented on some Terragen's work here as though nature just couldn't do...<fill-in-the-blank>, including everything from clouds to caves. While nature is still a pattern for realistic renders, sometimes it's our frame of reference that keeps us from seeing what nature really is.