here's an old model from the 19th century of memory which actually in the 21st century has come 00:13:03 back as a pretty good one as a metaphor anyway so the idea is that rain comes down on the ground and there's a little regularities randomly there and at some point those regularities will be a 00:13:17 little more responsive to the rain and a little channel will form the channel acts as an amplifier and so wherever that channel got started it starts funneling lots more water through it other water is draining into 00:13:31 it and all of a sudden it starts cutting deeper and you get these gullies and you get down into these gullies you have to remember to look up because everything 00:13:44 down there in this gully is kind of pink you can think that the world is pink and in fact if you get into a real gully one of my favorites is Grand Canyon by the 00:13:57 way that's only a hundred million years of erosion to get the Grand Canyon it's relatively recent get into one of these things and the enormity of what you see 00:14:08 outwards Dwarfs what you can see if you look up if you've ever been on one of these things you're just in a different world it's a pink world you don't think 00:14:23 about climbing out of it you think about moving along in it