How do archaeologists date old artefacts?

Archaeologists often combine several dating methods rather than rely on just one. Stratigraphy studies the layers of soil and debris, with deeper layers usually being older than those above them. Organic materials such as wood, bone, or charcoal can be dated using radiocarbon dating, which measures the decay of carbon-14 and is useful up to about 50,000 years. Pottery, stone tools, and buildings may also be dated by style, association, or other scientific methods such as thermoluminescence. These techniques help build timelines for human history, trade, and settlement.