You are of course right, the Grand Canyon is vastly larger. The effect on my brain was still the same. I think maybe what happens is that some object break our

You are of course right, the Grand Canyon is vastly larger. The effect on my brain was still the same. I think maybe what happens is that some object break our ability to relate a thing back to human dimensions. I don't get the same effect when looking at a skyscraper; maybe that's because each floor is usually visibly marked, so it can be related back to the self.