geochronology Dating methods

1.1 Radiometric dating

1.2 Fission-track dating

1.3 Cosmogenic nuclide geochronology

1.4 Luminescence dating

1.5 Incremental dating

1.6 Paleomagnetic dating

1.7 Magnetostratigraphy

1.8 Chemostratigraphy

1.9 Correlation of marker horizons

https://en.wikipedia.org/wiki/Geochronology Scientists have developed a bunch of methods, for example quartz when hidden from sunlight develops some chemical changes over time, so we can tell when a quartz was last exposed to sunshine. They also can use pollen in the soil and find what era of history that tree belongs to. They can also use carbon like charcoal and do carbon dating. Generally they need to define strata where all the rocks were laid together and use multiple chemical dating methods.