I am an archaeologist who works mainly on the Great Plains; I have also worked in the Colorado mountains, coastal California, the California desert, the Great Basin, Germany, and Ireland. I have a major technical interest in the study of how ancient people made and used stone tools. My research has focused on how human use of the Plains landscape responded to long-term environmental change during the Paleoindian period (from roughly 11,000 to 8000 BC). My recent research looks at the archaeology of farmers on the central and northern Plains during the last 1000 years. I am have completed fieldwork on a small-scale 12th century horticultural community on the Pine Ridge in northwestern Nebraska. My current project examines social and other changes in the history of the Pawnee and Arikara nations during the 13th and 14th century, with fieldwork on the Lynch site on Ponca Creek in northeastern Nebraska.