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Archeology for Interpreters > 5. How Do Archeologists Figure Out How Old Things Are?

Artifacts as time markers

Diagnostic stone tools

(photo) Historic-period Iron projectile point.

One of ten historic period iron arrowheads recovered at Little Bighorn Battlefield National Monument. (Midwest Archeological Center, NPS)

Chronologically diagnostic stone tools such as projectile points, knives, and scrapers appear at most prehistoric archeological sites. However, because the materials available to prehistoric people vary regionally and locally, only regional typologies can be developed.

Although prehistoric cultural groups and site occupation patterns also vary regionally, archeologists assign diagnostic artifacts to some general prehistoric time periods. These include the Paleo-Indian Period (ca. 13,000 BC to 7,900 BC), the Archaic Period (8,000 BC to 1,000 BC ), the Woodland Period (1000 BC to AD 1000), the Mississippian and Late Prehistoric Period (AD 900 to 1700), and the Historic Period (after European contact).

Fun fact

(photo) Archaic-period Kirk projectile point.

People produced stone tools from locally available materials or traded with other cultural groups for non-local materials and goods. To find places in your state where you can learn about the prehistoric cultural groups that occupied your area and the stone tools they made, visit the Regional Resources section of this guide. For a general introduction, visit Principles of Lithic Technology.