Identification_Information: Citation: Citation_Information: Originator: Robert B. Scott Originator: Ralph R. Shroba Originator: Anne E. Egger Publication_Date: 2001 Title: Geologic map of the Rifle Falls quadrangle, Garfield County, Colorado Edition: 1.0 Geospatial_Data_Presentation_Form: map Series_Information: Series_Name: Miscellaneous Field Studies Map Issue_Identification: MF-2341 Online_Linkage: http://geology.cr.usgs.gov/pub/mf-maps/mf-2341/ Publication_Information: Publication_Place: Denver, Colorado Publisher: U.S. Geological Survey Description: Abstract: New 1:24,000-scale geologic map of the Rifle Falls 7.5' quadrangle, in support of the USGS Western Colorado I-70 Corridor Cooperative Geologic Mapping Project, provides new interpretations of the stratigraphy, structure, and geologic hazards in the area of the southwest flank of the White River uplift. Bedrock strata include the Upper Cretaceous Iles Formation through Ordovician and Cambrian units. The Iles Formation includes the Cozzette Sandstone and Corcoran Sandstone Members, which are undivided. The Mancos Shale is divided into three members, an upper member, the Niobrara Member, and a lower member. The Lower Cretaceous Dakota Sandstone, the Upper Jurassic Morrison Formation, and the Entrada Sandstone are present. Below the Upper Jurassic Entrada Sandstone, the easternmost limit of the Lower Jurassic and Upper Triassic Glen Canyon Sandstone is recognized. Both the Upper Triassic Chinle Formation and the Lower Triassic(?) and Permian State Bridge Formation are present. The Pennsylvanian and Permian Maroon Formation is divided into two members, the Schoolhouse Member and a lower member. All the exposures of the Middle Pennsylvanian Eagle Evaporite intruded into the Middle Pennsylvanian Eagle Valley Formation, which includes locally mappable limestone beds. The Middle and Lower Pennsylvanian Belden Formation and the Lower Mississippian Leadville Limestone are present. The Upper Devonian Chaffee Group is divided into the Dyer Dolomite, which is broken into the Coffee Pot Member and the Broken Rib Member, and the Parting Formation. Ordovician through Cambrian units are undivided. The southwest flank of the White River uplift is a late Laramide structure that is represented by the steeply southwest-dipping Grand Hogback, which is only present in the southwestern corner of the map area, and less steeply southwest-dipping older strata that flatten to nearly horizontal attitudes in the northern part of the map area. Between these two is a large-offset, mid-Tertiary(?) Rifle Falls normal fault, that dips southward placing Leadville Limestone adjacent to Eagle Valley and Maroon Formations. Diapiric Eagle Valley Evaporite intruded close to the fault on the down-thrown side and presumably was injected into older strata on the upthrown block creating a blister-like, steeply north-dipping sequence of Mississippian and older strata. Also, removal of evaporite by either flow or dissolution from under younger parts of the strata create structural benches, folds, and sink holes on either side of the normal fault. A prominent dipslope of the Morrison-Dakota-Mancos part of the section forms large slide blocks that form distinctly different styles of compressive deformation called the Elk Park fold and fault complex at different parts of the toe of the slide. The major geologic hazard in the area consist of large landslides both associated with dip-slope slide blocks and the steep slopes of the Eagle Valley Formation and Belden Formation in the northern part of the map. Significant uranium and vanadium deposits were mined prior to 1980. Purpose: This map was funded by the National Cooperative Geologic Mapping Program. The map is a product of the I-70 Urban Corridor Project. This corridor is experiencing rapid urban growth and geologic mapping is needed to aid in land development planning in order to address, avoid, or mitigate known and potential geologic hazards. Supplemental_Information: Map political location: Garfield County, Colorado Compilation scale: 1:24,000 Geology mapped from 1992 to 1998 Compilation completed November 1998 Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2000 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: none planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -107.75 East_Bounding_Coordinate: -107.625 North_Bounding_Coordinate: 39.75 South_Bounding_Coordinate: 39.625 Keywords: Theme: Theme_Keyword_Thesaurus: AGI Glossary of Geology Theme_Keyword: Geologic map Theme_Keyword: Cambrian to Cretaceous sedimentary rocks Theme_Keyword: Tertiary to Quaternary surficial deposits Theme_Keyword: Laramide deformation Theme_Keyword: Neogene evaporite deformation Theme_Keyword: Landslide hazards Theme_Keyword: Uranium and vanadium deposits Place: Place_Keyword_Thesaurus: none Place_Keyword: USA Place_Keyword: Colorado Place_Keyword: Garfield County Access_Constraints: none Use_Constraints: none. Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Robert B. Scott Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: MS 913, Box 25046 DFC City: Denver State_or_Province: CO Postal_Code: 80225-0046 Contact_Voice_Telephone: 303-236-1230 Contact_Electronic_Mail_Address: rbscott@usgs.gov Browse_Graphic: Browse_Graphic_File_Name: