Dating

Dating in Archaeology: How We Determine the Age of Artifacts & Sites

Dating methods in archaeology help establish chronologies of past human activity by determining the age of artifacts, structures, and environmental changes. There are two main categories:

1. Relative Dating – Determines the sequence of events but not the exact age.

2. Absolute Dating – Provides a specific age or range in years.

1. Relative Dating Methods (Ordering events without exact dates)

A. Stratigraphy

• Based on the principle that deeper layers (strata) are older than upper layers.

• Useful for sites with undisturbed soil layers like caves or riverbeds.

B. Typology & Seriation

• Typology: Comparing artifact styles (e.g., pottery, tools) to known historical examples.

• Seriation: Arranging artifacts in a sequence based on changes in style or decoration over time.

C. Fluorine Dating

• Measures the amount of fluorine absorbed by bones from groundwater.

• Used for comparing bones at a site but doesn’t give an exact date.

2. Absolute Dating Methods (Assigning a precise date or range)

A. Radiocarbon Dating (C-14) – Up to ~50,000 years ago

• Measures carbon-14 decay in organic materials (wood, bone, charcoal).

• Used widely in prehistoric archaeology but less effective for very old sites.

B. Dendrochronology (Tree-Ring Dating) – Up to ~10,000 years ago

• Uses growth rings in trees to date wooden artifacts or structures.

• Very precise but requires overlapping sequences of ancient wood.

C. Potassium-Argon (K-Ar) Dating – Over 100,000 years ago

• Used to date volcanic rock by measuring potassium-40 decay.

• Essential for dating early human fossils in Africa.

D. Thermoluminescence (TL) – Up to ~500,000 years ago

• Measures trapped electrons in heated materials (pottery, burnt stone).

• Useful for dating ancient ceramics or fire pits.

E. Optically Stimulated Luminescence (OSL) – Up to ~200,000 years ago

• Dates sand and soil by measuring the last time they were exposed to sunlight.

• Used in prehistoric sites and buried landscapes.

F. Uranium-Series Dating – Up to ~500,000 years ago

• Measures uranium decay in cave formations (stalactites, stalagmites) and bones.

• Used in Neanderthal and early human sites.

Choosing the Right Dating Method

• Organic materials (wood, bone) → Radiocarbon dating

• Volcanic rock → Potassium-Argon dating

• Pottery, burned objects → Thermoluminescence

• Wooden structures → Dendrochronology

• Buried sand layers → Optically Stimulated Luminescence

Stratigraphy Excercise.