Twenty-seven 14C dates from alluvial deposits and soils exposed in modern arroyos near Zuni Salt Lake, New Mexico, provide evidence for past episodes of piedmont and valley entrenchment by low-order ephemeral streams. We recognize two episodes of entrenchment at A.D. 900?1050 and A.D. 1300?1400 that correlate to other arroyo-cutting events in the region. Episodes of piedmont and valley entrenchment are followed by approximately 200?300 years of aggradation until arroyos are filled and shallow flooding with expansive sedimentation returns, completing an alluvial cycle. Many alluvial cycles appear synchronous across much of the southern Colorado Plateau and are likely linked to changes in climate and flood regime. Flooding on small basin [...]