Geologic Map of the Gila Hot Springs 7.5' Quadrangle, and the Gila Cliff Dwellings National Monument, Catron and Grant Counties, New Mexico By James C. Ratté,1 David L. Gaskill,1 and James R. Chappell 2 1 U.S. Geological Survey 2 Colorado State University, Fort Collins, Colo. 2014 U.S. Geological Open-File Report 2014-1036 ABSTRACT The Gila Hot Springs quadrangle is of geologic interest with respect to four major features, which are: 1) The caves of the Gila Cliff Dwellings National Monument 2) The hot springs associated with the faults of the Gila Hot Springs graben 3) The Alum Mountain rhyolite dome and eruptive center 4) A proposed segment of the southeastern wall of the Gila Cliff Dwellings caldera The Gila Cliff Dwellings National Monument consists of two tracts. The caves that were inhabited by the Mogollon people in the 14th century are in the main tract near the mouth of Cliff Dweller Canyon in the Little Turkey Park 7.5' quadrangle adjoining the northwest corner of the Gila Hot Springs quadrangle. The second tract includes the the Cliff Dwellings National Monument Visitor Center at the confluence of the West and Middle Forks of the Gila River in the northwest corner of the Gila Hot Springs quadrangle. Both quadrangles are within the Gila National Forest and the Gila Wilderness except for a narrow corridor that provides access to the National Monument and small ranching and residential community at Gila Center in the Gila River valley. The caves in Cliff Dweller Canyon were developed in the Gila Conglomerate of probable Miocene? and Pleistocene? age in this area by processes of lateral corrosion and spring sapping along the creek in Cliff Dweller Canyon. The hot springs in the Gila River valley are localized along faults in the deepest part of the Gila Hot Springs graben, which cuts diagonally northwest-southeast across the central part of the quadrangle. Some of the springs provide domestic hot water for space heating and agriculture in the Gila River valley and represent a possible thermal resource for development at the Cliff Dwellings National Monument. The Alum Mountain rhyolite dome and eruptive center in the southwestern part of the quadrangle is a colorful area of altered and mineralized rocks that is satellitic to the larger Copperas Canyon eruptive center, both being part of the composite Copperas Creek volcano, or volcanic complex in the Copperas Peak quadrangle to the south. The altered rocks of the Alum Mountain eruptive center have been prospected by means of several short adits, or tunnels, for alum, a mixture of the iron and aluminum sulfate minerals: alunite and halotrichite. A fault on the west side of the Gila River, opposite the hot springs in the south-central part of the map area, just north of Alum Mountain, is tentatively interpreted as a segment of the wall of the Gila Cliff Dwellings caldera. The fault, which dips about 55 degrees northwest, has a footwall of the andesitic and dacitic lava flows and flow breccias of Gila Flat. The hanging wall consists of Bloodgood Canyon Tuff overlain by Bearwallow Mountain Andesite flows. However, these rocks are not faulted against the older rocks, but apparently abut and locally overlap the footwall. These are the major geologic features of the quadrangle, about three quarters of which is covered by Bearwallow Mountain Andesite lava flows and overlying volcaniclastic rocks of the Gila Conglomerate. DISCLAIMERS Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 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DATA FILES List of files: 00ReadMe.txt OF2014-1036.pdf OF2014-1036.met Datafiles.zip directory gcl_geology.mxd gcl_geology.gdb gicl giclatd: Geologic attitude observation localites (strikes and dips) gicldef: Deformation area gicldefa: Deformation area boundaries gicldke: Linear dikes giclflt: Faults giclglg: Geologic unit polygons giclglga: Geologic contacts giclgpf: Geologic point features giclhzl: Hazard feature lines giclmin: Mine point features giclsec: Geologic cross section lines giclgsl: Geologic sample localites giclvlf: Caldera boundaries giclgln: Linear geologic unit OF2014-1036_shapefiles folder: giclatd_Geologic_Attitude_Observation_Localities.shp (dbf/prj/sbn/sbx/shp.xml/shx) gicldef_Deformation_areas.shp (dbf/prj/sbn/sbx/shp.xml/shx) gicldefa_Deformation_area_boundaries.shp (dbf/prj/sbn/sbx/shp.xml/shx) gicldke_Linear_dikes.shp (dbf/prj/sbn/sbx/shp.xml/shx) giclflt_Faults.shp (dbf/prj/sbn/sbx/shp.xml/shx) giclglg_geologic_unit_poly.shp (dbf/prj/sbn/sbx/shp.xml/shx) giclglga_Geologic_contacts.shp (dbf/prj/sbn/sbx/cpg/shx) giclgpf_Geologic_point_features.shp (dbf/prj/sbn/sbx/shp.xml/shx) giclhzl_Hazard_feature_lines.shp (dbf/prj/sbn/sbx/shp.xml/shx) giclmin_Mine_point_features.shp (dbf/prj/sbn/sbx/shp.xml/shx) giclsec_cross_section_lines.shp (dbf/prj/sbn/sbx/shp.xml/shx) giclgsl_Geologic_sample_localities.shp (dbf/prj/sbn/sbx/shp.xml/shx) giclvlf_Caldera_boundaries.shp (dbf/prj/sbn/sbx/shp.xml/shx) giclgln_Linear_geologic_unit.shp (dbf/prj/sbn/sbx/shp.xml/shx) gcl_metdata.txt -- metadata for National Park Service Gila Cliff Dwellings National Monument GRI Ancillary Map Information Document HOW TO OBTAIN THE DIGITAL FILES The digital files constituting the geologic map database of this report can be obtained via the Internet from the U.S. Geological Survey publications website. Go to the web page at http://pubs.usgs.gov/sim/3283/ or http://dx.doi.org/10.3133/ofr20141036 and follow the directions to download the files. The main product is a Portable Document Format (.pdf) map, which requires Adobe Acrobat for viewing, and from which paper copies may be printed. Acrobat software runs on a variety of systems, and is available for download free of charge from Adobe at http://www.adobe.com. ArcReader may be downloaded free of charge from http://www.esri.com/software/arcgis/arcreader/download.htm for viewing additional files included in this report.