Fission track dating is a remarkable radiometric technique used to determine the age of ancient materials. It works by counting tiny, microscopic damage trails, called "fission tracks," left behind in crystals and glass. These tracks are created when a rare, naturally occurring isotope, Uranium-238 (U-238), spontaneously fissions, or splits, within the material. Each fission event leaves two energetic fragments that recoil, damaging the surrounding material.

To date a sample, scientists count these accumulated fossil tracks under a microscope. Then, the sample is irradiated with neutrons to induce more fissions, which helps determine the original amount of U-238. Comparing the old tracks to the new, induced ones, along with the known decay rate of U-238, reveals the age of the material.

Applications:
This method is invaluable in palaeoanthropology and archaeology. It's particularly useful for:

1. Dating volcanic ash layers associated with early hominin sites, providing precise timelines for human evolution.

2. Dating obsidian artifacts directly, helping reconstruct ancient trade routes and technological developments.

3. Establishing chronologies for geological formations that encapsulate archaeological evidence