The Grave Creek Phase began about 3,500 years ago and lasted until about 2,000 years ago. Generally, similar large game was hunted (deer and elk) as well as mountain sheep. During this phase, river mussels became an important food resource rather than just an occasional addition to the diet. The climate during this phase is characterized with cool, wet winters and warm, moist summers. There is a general increase in precipitation and decrease in temperature.

 

Artifacts change in frequency, with an increase in the number of grinding tools. The mano is a long, smoothed stone used in conjunction with a flat grinding stone. The mano was pushed back and forth across the flat grinding stone and was typically used to grind seeds.

 

Other grinding tools are represented by hopper mortar bases and pestles, which were stone tools used to grind roots. A shallow depression was pecked into a large stone. Then a basket (without a bottom) was attached to the stone, over the depression. Roots were then placed inside the depression and basket, and pulverized with the pestle.

Projectile Points and fragments of the Grave Creek Phase. Scale and divisions are in Centimeters. (Source: Cultural Chronology of the Lower Salmon River (pdf), DAVIS, Loren G., Department of Anthropology, Oregon State University) Read about the evolution of projectile points.