A review of previous data sets and recent research indicates that Humboldt Basal-notched biface forms are characterized by distinctive temporal spans within the prehistoric record of the southwestern Great Basin. Contrary to previous conclusions, we believe that the biface forms had two distinct periods of use, an early (4000 to 500 B.C.) and a late (500 B.C. to A.D. 800) manifestation. Humboldt Basal-notched bifaces from these two periods can be differentiated typologically and perhaps functionally.
