You know from previous blog posts that tree rings contain a lot of climate information encoded in the thickness of each annual ring, including information about temperature and precipitation as well as some occasional information about fires, floods and other impactful events. But you might not know that tree rings can also be used to date historic buildings, picture frames and other objects made out of wood. By looking at the patterns of tree rings over time in those objects and comparing their patterns to known ring patterns from other trees in the area, historians can identify when the objects were made and thus date them using the tree rings as a proxy for the calendar as stored in the ring patterns. Atlas Obscura has an interesting story about how some buildings from early America have been dated using this method here.

Source: Pauline Eccles, Commons Wikimedia