Archaeologists pay close attention to the layers of materials in a site. Stratigraphy is the layering of deposits at an archaeological site. Cultural evidence and natural sediments become buried over time. The bottom layer is the oldest; the top layer is the youngest.
Stratigraphy...
The crew rented an old three-story house, which- telling from the numerous chips in the exterior paint- had been pink, orange, white, and blue in recent years. It was a simple lesson in archaeology all in itself; a demonstration of stratigraphy, the study of layers. Top layer, new; bottom layer, old.