Theodore R. Brandt Joseph P. Colgan 20231002 1.2 Geodatabase Denver, Colorado U.S. Geological Survey Author ORCID list: Theodore R. Brandt 0000-0002-7862-9082 Joseph P. Colgan 0000-0001-6671-1436 https://doi.org/10.5066/P95MSFVF Roger B. Colton 1978 1.0 map USGS Miscellaneous Investigations Series I-855-G Denver, Colorado U.S. Geological Survey http://pubs.usgs.gov/imap/855/G/ This digital map shows the geographic extent of rock stratigraphic units (formations) as compiled by Colton in 1976 under the Front Range Urban Corridor Geology Program. Colton used his own geologic mapping and previously published geologic maps to compile one map having a single classification of geologic units. The resulting published color paper map (USGS Map I-855-G, Colton, 1978) was intended for land-use planning and to depict the regional geology. In 1997-1999, another USGS project designed to address urban growth issues was undertaken. This project, the USGS Front Range Infrastructure Resources Project, undertook to digitize Colton's map at 1:100,000 scale, making it useable in Geographical Information Systems (GIS). That product is described here. In general, the digitized map depicts in its western part Precambrian igneous and metamorphic rocks, Pennsylvanian and younger sedimentary rock units, major faults, and brecciated zones along an eastern strip (5-20 km wide) of the Front Range. The central and eastern parts of the map (Colorado Piedmont) show a mantle of Quaternary unconsolidated deposits and interspersed outcrops of sedimentary rock of Cretaceous or Tertiary age. A surficial mantle of unconsolidated deposits of Quaternary age is differentiated and depicted as eolium (wind-blown sand and silt), alluvium (river gravel, sand, and silt of variable composition), colluvium, and a few landslide deposits. At the mountain front, north-trending, Paleozoic and Mesozoic formations of sandstone, shale, and minor limestone dip mostly eastward and form folds, fault blocks, hogbacks and intervening valleys. Local dikes and sills of Tertiary rhyodacite and basalt intrude rocks near the range front, mostly in the Boulder area. Land-use planners of many kinds (including National Forest managers, developers, city and rural planners, and highway builders) need accurate geologic data with which to make informed decisions. The map is also part of the National Geologic Database, which is intended as digital framework for the entire country. Database follows the USGS Geologic Map Schema(GeMS) [https://ngmdb.usgs.gov/Info/standards/GeMS/] 1978 publication date Complete none currently planned -105.3750 -104.6250 40.6250 40.0000 AGI Glossary of Geology Geologic map Quaternary deposits eolian sand alluvial gravel landslide deposit geologic hazard land-use planning urban growth urban zoning aggregate mine subsidence Paleocene and Eocene igneous rocks Cretaceous rocks Paleozoic rocks Silver Plume quartz monzonite Boulder Creek granodiorite Precambrian rocks US GeoFramework Initiative USGI National Geologic Synthesis Project NGS National Cooperative Geologic Mapping Program NCGMP Geologic Map Schema GeMS USGS Metadata Identifier USGS:635a935cd34ebe4425047121 U.S. Board of Geographic Names (BGN) Geographic Names Information System (GNIS) USA United States of America Colorado Boulder County Weld County Larimer County Boulder Fort Collins Greeley Colorado Front Range Colorado Piedmont Front Range Urban Corridor Jefferson County Geologic Names Committee Lexicon (Geolex) Quaternary Holocene Pleistocene Pinedale Glaciation Bull Lake Glaciation Sangamon Interglaciation Illinoian Glaciation Yarmouth Interglaciation Kansan Glaciation Aftonian Interglaciation Nebraskan Glaciation Pliocene Eocene Paleocene Cretaceous Jurassic Triassic Permian Pennsylvanian Precambrian Y Precambrian X none Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Joseph P. Colgan U.S. Geological Survey mailing

Denver Federal Center

Denver CO 80225-0046 USA (303) 236-1021 tbrandt@usgs.gov https://pubs.usgs.gov/imap/855/G/i-855-g_v1.0.pdf Graphical representation of the map PDF Theodore R. Brandt, U.S. Geological Survey, served as primary author of the GIS database. David Moore, U.S. Geological Survey, retired, assisted in proofing the geologic data in the version 1.1 database. Joseph Colgan reconciled data and metadata reviews and completed publication after Ted retired. Windows_10, Intel ArcInfo version 10.7.1 Theodore R. Brandt David W. Moore Kyle E. Murray 2003 version 1.0 map USGS Open-File Report OFR-03-024 Denver, Colorado, U.S.A. United States Geological Survey http://pubs.usgs.gov/of/2003/ofr-03-024/ Data were entered and checked by the geologist that compiled the geodatabase. The attributes of this geospatial data set consist of text identifiers and numeric codes that indicate the identity of the geologic unit or type of geologic feature. To check attribute accuracy, a color computer screen representation was visually compared to the geologist's original compilation. Discrepancies between the digital geospatial dataset and the original analog or digital compilation were corrected as needed. Machine-created listings of unique attribute values were used to identify spelling errors or other inconsistencies, and corrections were made as needed. Map elements were visually checked for overshoots, undershoots, duplicate features, polygon closure, and other errors by the lead author and by the GIS technician(s) that created the digital database. Automated (ArcGIS) routines were also used to check the databases for polygon label errors, line or point attribution errors, sliver polygons, dangling arcs, intersection errors, and projection information. Check plots of the map were reviewed by at least one other geologist for consistency with basic geologic principles and general conformity to USGS mapping standards. Data are complete: no features that could be accurately represented at the compilation scale of 1:100,000 were eliminated or generalized. The smallest area represented is approximately 240 square meters. All geospatial database elements are attributed. Most digitized positions on the map that depict distinct contacts between rock formations in the field are estimated to be within 20 m of the actual contact on the land in most instances. Boundaries (lines) between Quaternary units (for example, terrace gravels) that correspond closely to distinct edges of landforms (for example, river terraces) are of comparable accuracy. Boundaries (lines) between some Quaternary units, such as eolian deposits and broad alluvial aprons, are approximately located within an indefinite gradational zone between them. Horizontal positional accuracy is tested by visual comparison of hard copy test plots to source maps or comparing locations of data on a computer monitor to other data layers in the same geographic area. The database contains no elevation data. Accuracy of these digital data indirectly depends on accuracy of the base maps on which the original source geologic maps were compiled. These base maps were made by the U.S. Geological Survey, which routinely checks them for compliance with the National Map Accuracy Standards. The geology for the published paper map was compiled by Roger Colton. 1976 The geologic database was compiled in Arc/Info. 1999 GIS database was converted to the GeMS data model. Geologic polygon, line, and point features were digitized, attributed and revised in ArcGIS. 2022 Metadata created by Ted Brandt. 2022 Metadata reviewed and revised by Ted Brandt. 2022 Vector Universal Transverse Mercator 13 .9996 -105.0000 0.00 500000.0000 0.0000 coordinate pair 5 5 meters North American Datum 1983(NAD 83) GRS_1980 6378137.0 298.2 Database follows the USGS Geologic Map Schema(GeMS) Attribute definitions and data structure can be found here: https://ngmdb.usgs.gov/Info/standards/GeMS/ All geologic feature descriptions refer to the FGDC Digital Cartographic Standard for Geologic Map Symbolization https://pubs.usgs.gov/tm/2006/11A02/ All geologic terms refer to definitions in the AGI Glossary of Geology **Not all components of the GeMS data model are utilized in this database** FEATURE DATASET: GeologicMap ---------------------------------------- FEATURE CLASS: ContactsAndFaults [Line Feature] DESCRIPTION OF FIELDS: Type: Term that categorizes what line represents IsConcealed: Indicates if feature is concealed LocationConfidenceMeters: Distance representing feature locational certainty, in meters from either side of feature ExistenceConfidence: Qualitative value representing certainty in existence of feature IdentityConfidence: Qualitative value representing certainty in identification of feature Label: Human readable name for a line feature Symbol: Numeric code that references "REF NO" column in USGS cartographic standards (https://pubs.usgs.gov/tm/2006/11A02/) (-9999 = no value) DataSourceID: Foreign key that relates to the DataSource_ID field in "DataSources" table Notes: Free text with additional information specific to feature ContactsAndFaults_ID: Primary key. Unique feature identifier (CAF*) ---------------------------------------- FEATURE CLASS: MapUnitPolys [Polygon Feature] DESCRIPTION OF FIELDS: MapUnit: Map unit symbol Name: Short unit name FullName: Full unit name that may include member/formation/group associations Age: Period or Epoch of unit consist with USGS time scale IdentityConfidence: Qualitative assessment of confidence for polygon identification Label: Map unit symbol Symbol: When used, indicates color and/or pattern used to symbolize polygon DataSourceID: Foreign key that relates to the DataSource_ID field in "DataSources" table Notes: Free text with additional information specific to feature MapUnitPolys_ID: Primary key. Unique feature identifier (MUP*) ---------------------------------------- FEATURE CLASS: DataSourcePolys [Polygon Feature] DESCRIPTION OF FIELDS: DataSourceID: Foreign key that relates to the DataSource_ID field in "DataSources" table Notes: Citation of publication or indication of "This Report" DataSourcePolys_ID: Primary key. Unique feature identifier (DSP*) ---------------------------------------- NON-SPATIAL TABLE: DataSources DESCRIPTION OF FIELDS: Source: Description of source Notes: Description of how source was used or acquired URL: URL link to data (at time of publication), if available DataSource_ID: Primary key. Unique to each data entry (DAS*) ---------------------------------------- NON-SPATIAL TABLE: GeoMaterialDict DESCRIPTION OF FIELDS: HierarchyKey: Text strip to document hierarchical relationships between terms GeoMaterial: Name of GeoMaterial IndentedName: GeoMaterial name with indents indicated by hyphens Definition: Definition of GeoMaterial ---------------------------------------- NON-SPATIAL TABLE: DescriptionOfMapUnits DESCRIPTION OF FIELDS: MapUnit: Map unit symbol Name: Short unit name FullName: Full unit name that may include member/formation/group associations Age: Period or Epoch of unit consist with USGS time scale Description Text description of map unit HierarchyKey: String of dash-delimited numeric values that illustrate the hierarchical relationship between units ParagraphStyle: Formatting paragraph style Label: Text string to place a unit symbol in map display Symbol: Area fill symbol in accompanying style AreaFillRGB: RGB values of area fill color AreaFillPatternDescription: Text description of patterns used in fill GeoMaterial: Term categorizing the dominant lithology in the map feature. Term derived from NGMD standard term list GeoMaterialConfidence: Qualitative term describing appropriateness of the GeoMaterial term used DescriptionOfMapUnits_ID: Primary key. Unique to each data entry (DMU*) ---------------------------------------- NON-SPATIAL TABLE: Glossary DESCRIPTION OF FIELDS: Term: Word for a concept Definition: Definition or source of definition of term DefinitionSourceID: Foreign key to "DataSources" non-spatial table Glossary_ID: Primary key. Unique to each data entry (GLO*) https://pubs.usgs.gov/tm/2006/11A02/ U.S. Geological Survey-ScienceBase mailing address

Denver Federal Center, Bldg. 810, Mail Stop 302

Denver CO 80225-0046 1-888-275-8747 sciencebase@usgs.gov Data Release Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey. Although this information product, for the most part, is in the public domain, it also may contain copyrighted material as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. This database has been approved for release and publication by the Director of USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. Although these data have been processed successfully on a computer System at the U.S. Geological Survey, no warranty, expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein. GDB 10.7.1 2019 In Windows, use WinZip (http://www.winzip.com/) or other programs to extract the file. https://doi.org/10.5066/P95MSFVF none 20231005 2022 Joseph P. Colgan U.S. Geological Survey mailing address

MS 980, Box 25046 Denver Federal Center

Denver CO 80225-0046 303-236-1021 jcolgan@usgs.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998