Both of these unifacial knife fragments are made from Edwards Plateau Chert from central Texas. Unifacial knives were an important, but often overlooked part of the Paleoindian toolkit. Overall morphology of these knives is determined by the shape and size of the flake used. The Blackwater Draw site had a close connection with the Edwards Plateau of south-central Texas in prehistoric times through the two prominent landforms near the site. These are the Blackwater Draw proper and the Pecos Valley. Following either of these will lead you directly to chert sources of the Edwards Plateau (click map to expand).