Abundant archaeological sites near the Tucson Mountains in southern Arizona occur on landforms formed by late Quaternary geological processes, some of which are still locally active today. Six depositional units of Quaternary age are identified in this report; four of these are of probable Holocene age. Each unit has a characteristic surface expression in terms of soil development, topographic relief, drainage density, and topographic position in relation to other units. Paleoindian Period artifacts are located on older fan remnants (Qfo) but may be buried at depth within Santa Cruz River alluvium (Qal). Archaic Period artifacts also occur on older fan remnants and may be buried along the river; however, several are also found within eolian dunes (Qeo) that contain sequences of buried soils. These dunes underwent a period of eolian sedimentation and artifact deposition, commencing at approximately 3000 14C years BP at two sites. More data are required to determine whether cultural preference, perhaps related to proto-agricultural activities, resulted in the apparent use of these dunes by Archaic peoples. Ceramic Period artifacts are located along modern drainage ways and along and in areas of Holocene alluvium. The Santa Cruz River to the east of the Tucson Mountains has downcut and terraced the valley floor deposits (Qvo and Qvy). The resulting base level changes cause young fan deposits to be inset against older ones. Buried Ceramic Period sites may be located within these relatively thick, younger fan deposits in this area.