Having an affinity for geology, this one readily caught my attention. James Hutton never really received the well-known-ness that Galileo, Copernicus, and Darwin did; but he should have. Hutton discovered that time went back much farther than was held in that day, and found the geological proof for that. An image of the unconformity at Siccar Point is often my computer's wallpaper. Great, quick read.