Geology has shaped human history, but humans are a force of nature ourselves, and we have changed geology. We can see this in action in Indonesia, where volcanoes spew out boiling mud instead of lava, as a result of man-made underground tunnels used to probe for natural gas. On the other side of the planet, we'll travel to the Canadian Rockies to peel back the historic record locked in ancient ice to see how man's earliest agriculture may have sparked global warming.
