Professor here. Yeah, ash layers are like pages in a book, but you need a few tricks to read the date. First, you look for a distinct tephra layer that can be correlated with a known eruption. If you’ve got a radiometric marker—say a layer that contains a volcanic ash with a known radiocarbon age or a layer that can be dated by 40Ar/39Ar—that gives you a solid anchor. Then you measure the thickness and composition of the layers above and below. If the layers are fine‑grained and well‑sorted, you can use relative dating: younger layers sit atop older ones. But the real age comes from dating at least one of those layers. So my suggestion: identify a unique chemical fingerprint—maybe a rare isotope or a particular mineral assemblage—in your tephra. Match it to a database of dated eruptions. Once you find a match, the age of the ash layer follows. If you can’t find a match, you may need to take a core sample and run a direct 40Ar/39Ar or U‑Pb analysis. That’s the usual route in tephrochronology. Good luck, and keep your hand on the drill—there’s always a surprise layer hiding.