There's nothing like being on the road, or wherever, and finding a sign about a geological subject. Usually we're on our own when it comes to spotting geology, but in rare places the authorities have seen fit to rouse people from their typical focus and get them to pay attention to the things you and I see routinely. That's what my collection of geological signs is about. Today I've added two signs from Yellowstone with different degrees of warning about the unusual hazards there. This one is the more dire: fall in here and you could die.
Courtesy Wesley Fryer of Flickr via Creative Commons license