Surficial geology and geologic hazards of the Northern Tucson Basin, Pima County, Arizona

This report and accompanying maps describe the surficial geology, geomorphology, and geologic hazards of the northern Tucson metropolitan area. The mapping covers the Tucson North and Sabino Canyon 7 1/2’ quadrangles and includes portions of the City of Tucson and unincorporated Pima County (Figure 1). The map area encompasses the northern part of the basin floor, the southern flank of the Santa Catalina Mountains, and the dissected piedmont between them known as the Catalina foothills. Basin floor areas have been thoroughly altered by urban development, and the Catalina foothills have undergone substantial development during the past 30 years or so. The mountains generally are within the Coronado National Forest and are not developed, but some homes have been built on the lower flanks of the mountains up to the forest boundary. This report is intended to enhance our understanding of the recent geologic development of the northern Tucson metropolitan area and to aid in assessing and understanding geologic hazards in this area. This surficial geologic mapping is part of continuing efforts by the AZGS to map the geology of the Phoenix – Tucson urban corridor, and it complements previous mapping efforts in the Tucson area (McKittrick, 1988; Jackson, 1989; Demsey and others, 1993; Field and Pearthree, 1993). We have incorporated recent mapping and description of the geologic framework of the Catalina foothills (Dickinson, 1999) into this map. The report is organized into a brief introduction and explanation of mapping methods, unit descriptions, a summary of the geologic and geomorphic framework of the area, and a discussion of geologic hazards. (28 pages)