This digital geospatial data set consists of bedrock-surface-altitude contours that were generated with a Geographic Information System (GIS). The U.S. Geological Survey developed this data set as part of a project that is presented in the report, Geohydrology of the Shallow Aquifers in the Denver Metropolitan Area, Colorado (Robson, 1996).
This data set was created by the U.S. Geological Survey (USGS) in the development of USGS Hydrologic Investigations Atlas HA-736 (Robson, 1996). This data set was used in the creation of a 1:50,000-scale contour map.
Procedures_Used Using Arc/INFO software, USGS 7.5-minute Digital Elevation Models (DEMs) that encompass the study area were converted to raster surface formats (grids, in ARC/INFO terminology) with the command DEMLATTICE. They were mosaicked into a single continuous surface with the ARC/INFO GRID function, MERGE, and projected into an appropriate coordinate system with the command, PROJECT. The resulting grid was then smoothed using an averaging filter with a radius of 9 grid cells (180 meters): Grid: lsdcir9 = focalmean (all_lsd7spc,circle,9,data) Line data sets (coverages, in ARC/INFO terminology) of unconsolidated- sediment thickness contours and bedrock-outcrop outlines (documented separately) were converted to a grid with the same cell size as the DEM-derived data (approximate 30-meter spacing between data points): Arc: createtin obtin96 # 30 Copyright (C) 1982-1995 Environmental Systems Research Institute, Inc. All rights reserved. CREATETIN Version 7.0.3(Mon Mar 13 22:21:55 PST 1995) Createtin: cover all_obsup line contour 1 Createtin: cover overburden line contour 1 Createtin: cover ../outcrop/all_ocspc3cl line contour 1 Createtin: end Weed tolerance set to default value 0.000... Loading arcs from coverage all_obsup... Weed tolerance 55.712, input arc points 6022,remaining 3735... Weed tolerance set to default value 0.000... Loading arcs from coverage overburden... Weed tolerance 48.345, input arc points 39674,remaining 21956... Weed tolerance set to default value 0.000... Loading arcs from coverage ../outcrop/all_ocspc3cl... Weed tolerance 48.290, input arc points 128315,remaining 29159... Proximal tolerance set to 30.000... Removing points within tolerance... Within tolerance 2201. Remaining 52649... Creating TIN... Writing TIN data structures... Arc: tinlattice obtin96 obgrd96b linear # The unconsolidated-sediment-thickness grid was subtracted from the land-surface-altitude grid to produce a grid of bedrock- surface altitude. The software generated the contour coverage at an interval of 20 feet using the bedrock-surface-altitude grid. This coverage was clipped to fit the study area boundary. Arc: brgrd96b = /gis/arcwork/temparc/shaqdems/lsdcir9 - /gis/users/robson/overburden/obgrd96b Arc: latticecontour brgrd96b brcnt96b 20 0 # 20 # Arc: clip brcnt96b /gis/users/robson/finals/studyarea brcnt96b1 line .001 The jagged appearance of the contours was addressed by smoothing the contours in an Arcedit session. Arc vertex grain tolerances (the minimum allowable distance between vertices in a line) were set to 90 meters, all the arcs were generalized with the Arcedit command, SPLINE, and the grain tolerances were set to 30 meters before splining the arcs again. The coverage was built with line topology. Manual editing corrected contours that were not correctly interpolated, as determined by consultation with the projects author; For example, contours that formed closed polygons with perimeters less than 200 meters, as well as contours that overlapped large lakes, were removed or altered. Arc items "TEXTKEY," "CNT_INT," and "DEPRESSION" were added to the arc attribute table of the coverage. Further editing delineated the different display characteristics of the arcs in a plotting routine. The Arc items "TEXTKEY" and "DEPRESSION" were attributed in this editing session. Hardcopy and base map overlays were used for reference. The final coverage is intended to be used as one thematic layer in a map to be published at a scale of 1:50,000. Revisions Revision 1.0, 09/16/94, original data set. Reviews_Applied July-August 1994: Colleague review of 1:50,000-scale maps that were generated from the original data set. Manuscript review included validation of method as outlined in map report and inspection for positional accuracy. January-Febuary 1996: Colleague review of original digital data set and associated metadata. Metadata review included verification of table and column/item identities and definitions, validation of the reference data sets and citations, verification of consistency between log file and documented procedures, and validation of development method as described in the documentation. March 1996: Inspection of 1:50,000-scale hardcopy generated from this data set. Related_Spatial_and_Tabular_Data_Sets None. Other_References_Cited Robson, S.G., 1996, Geohydrology of the shallow aquifers in the Denver metropolitan area, Colorado: U.S. Geological Survey Hydrologic Investigations Atlas HA-736, 5 sheets, scale 1:50,000. Notes Char, Stephen J., Sieverling, Jennifer B., and Miller, L. Lee, 1996, Digital geospatial data sets used in the study of geohydrology of the shallow aquifers in the Denver metro- politan area, Colorado: a)Bedrock outcrop, b)Unconsolidated- sediment thickness, c)Water-table altitude, d)Bedrock- surface altitude, e)Depth to water, and f)Saturated-zone thickness: U.S. Geological Survey Open-File Report 96-659. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this metadata file is designed to conform to the Federal Geographic Data Committee Spatial Metadata Content Standard, these data and this metadata file were developed using ARC/INFO software; therefore, this file includes ARC/INFO-specific terminology. Data used to develop this project was obtained from many sources, including the following: Cherry Creek Valley Water and Sanitation District City of Brighton Colorado Department of Health Colorado Department of Highways Colorado State Engineers Office Cooley Sand and Gravel Denver Federal Center Denver Water Department EG&G Rocky Flats Incorporated Environmental Protection Agency (Superfund) Frei & Sons (Sand and Gravel) HRS Consultants Lowry Air Force Base Metro Denver Wastewater Reclamation District Public Service Company Rocky Mountain Arsenal U.S. Army Corps of Engineers Urban Drainage and Flood Control Western Mobile Incorporated
This data set should not be used at a scale larger than 1:50,000.
Box 25046, MS 415, Denver Federal Center
U.S. Army--Rocky Mountain Arsenal U.S. Department of Energy--Rocky Flats Field Office Colorado Department of Public Health and Environment Colorado Department of Natural Resources--State Engineers Office Denver Water Department Littleton-Englewood Wastewater Treatment Plant East Cherry Creek Valley Water and Sanitation District Metro Wastewater Reclamation District Willows Water District Cities of Aurora, Lakewood, and Thornton
See Entity_Attribute_Information
Polygon and chain-node topology present.
The contours that comprise two of the input data sets (overburden and all_obsup) were digitized by hand at a scale of 1:24,000 from hand-drawn maps. The hand-drawn contours for overburden were interpolated at 20-foot intervals using data from wells whose locations were reported in Public Land Survey System coordinates. The well locations are theoretically accurate to the nearest quarter-quarter-quarter-quarter section, but they were not field-checked for accuracy. Also, the well locations were not evenly distributed throughout the study area. The limited number of supplemental hand-drawn contours that comprise all_obsup were interpolated at 10-foot intervals and were intended to enhance the surface interpolation in areas where the CREATETIN session failed to accurately represent the unconsolidated-sediment-thickness surface.
The contours that comprise two of the input data sets (overburden and all_obsup) were digitized by hand at a scale of 1:24,000 from hand-drawn maps. The hand-drawn contours for overburden were interpolated at 20-foot intervals using data from wells whose locations were reported in Public Land Survey System coordinates. The well locations are theoretically accurate to the nearest quarter-quarter-quarter-quarter section, but they were not field-checked for accuracy. Also, the well locations were not evenly distributed throughout the study area. The limited number of supplemental hand-drawn contours that comprise all_obsup were interpolated at 10-foot intervals and were intended to enhance the surface interpolation in areas where the CREATETIN session failed to accurately represent the unconsolidated-sediment-thickness surface. The bedrock-outcrop outlines that comprise another input data set also were digitized by hand at a scale of 1:24,000 from hand-drawn maps. The hand-drawn outlines were not field-checked for accuracy.
SJCHAR LATTICECONTOUR BRGRD96B BRCNT96B 20 0 # 20 #
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B
SJCHAR BUILD BRCNT96B LINE
SJCHAR CLIP BRCNT96B /GIS/USERS/ROBSON/FINALS/STUDYAREA BRCNT96B1 LINE .001
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR RESTOREARCEDIT BRCNT96B1 BRCNT96B2
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1
SJCHAR BUILD BRCNT96B1 LINE
SJCHAR COPY BRCNT96B1 BRCNT96B1A
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR GRAIN 90,SPLINE,GRAIN 30,SPLINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR COLLAPSED ISLANDS W/200 METER CIRCUMFERENCES REMOVED
SJCHAR BUILD BRCNT96B1A
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD BRCNT96B1A LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD BRCNT96B1A LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD BRCNT96B1A LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD BRCNT96B1A LINE
SJCHAR ALTERED CONTOURS COINCIDENT WITH LARGE LAKES
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD BRCNT96B1A LINE
SJCHAR ARCEDIT /HOME/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD BRCNT96B1A LINE
SJCHAR REMOVED ISLAND ARC OVER STANLEY LAKE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD BRCNT96B1A LINE
SJCHAR IDEDIT BRCNT96B1A LINE
SJCHAR INFO ALTER .AAT TO CHANGE TEXTFLAG ITEM TO TEXTKEY
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR IDEDIT BRCNT96B1A LINE
SJCHAR INFO ALTERED EXTRA-ID NAME TO DEPRESSION
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR SPLITTING OF ARCS AND ATTRIBUTING FOR ARCTEXT LABEL PLACEMENT
SJCHAR REMOVED ISLAND ARCS LT 600 METERS CIRCUMFERENCE
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR ARCEDIT /WORK/GIS1WORK2/ROBSON/BRCNT96B1A
SJCHAR BUILD /WORK/GIS1WORK2/ROBSON/BRCNT96B1A LINE
SJCHAR DOCUMENT BRCNT96B1A UPDATE SJCHAR
SJCHAR DOCUMENT BRCNT96B1A UPDATE SJCHAR
SJCHAR DOCUMENT BRCNT96B1A UPDATE SJCHAR
SJCHAR RENAME BRCNT96B1A BEDROCK
SJCHAR DOCUMENT BEDROCK UPDATE SJCHAR
SJCHAR DOCUMENT BEDROCK UPDATE SJCHAR
SJCHAR DOCUMENT BEDROCK UPDATE SJCHAR
SJCHAR DOCUMENT BEDROCK UPDATE SJCHAR
SJCHAR COPY /WORK/GIS1WORK2/ROBSON/BEDROCK BEDROCK
SJCHAR DOCUMENT BEDROCK UPDATE SJCHAR
SJCHAR EXPORT COVER BEDROCK BEDROCK
SJCHAR EXPORT COVER BEDROCK BEDROCK
Polygon attribute table
U.S. Geological Survey
Area of poly/region in square coverage units
Computed
Perimeter of poly/region in coverage units
Computed
Internal feature number
Computed
User-assigned feature number
User-defined
Arc attribute table
U.S. Geological Survey
Internal number of from-node
Computed
Internal number of to-node
Computed
Internal number of poly to left of arc
Computed
Internal number of poly to right of arc
Computed
Length of arc in coverage units
Computed
Internal feature number
Computed
User-assigned feature number
User-defined
Bedrock surface altitude, in feet above sea level
U.S. Geological Survey
Bedrock surface altitude, in feet above sea level
U.S. Geological Survey
One-character-wide key used in plotting of text
U.S. Geological Survey
One-character-wide key to indicate lines which delineate depression features
U.S. Geological Survey
Character-formatted item of integer item CNT_INT
U.S. Geological Survey
Arc attribute "CONTOUR" is the bedrock surface altitude in feet above sea level. Arc attribute "CNT_INT" is the integer equivalent of item "CONTOUR" and was used to create item "CNT_CHR." Arc attribute "CNT_CHR" is the character equivalent of item "CNT_INT," used for selecting 100-foot index contours (that is, CNT_INT containing "00"). Arc attribute "DEPRESSION" indicates whether or not a line delineates a depression feature. Lines that delineate depressions are coded as "Y"; non-depression features are coded as "N." Arc attribute "TEXTKEY" indicates how contour values are drawn in a plotting routine: B = no text drawn. S = text drawn using splined blank white mask. G = text drawn using splined blank gray mask. Q = special case, changed textspacing and textmask rectangle size.
Not Available
Box 25046, MS 415, Denver Federal Center
Although this data set has been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
bedrock surface altitude contours geographic features
bedrock surface altitude contours geographic features
ArcIMS Image Map Service
A web-based interactive mapping system that accesses an ArcIMS Map Service running on certmapper.cr.usgs.gov.
Topological Vector Profile
Download via Internet using World-Wide Web browser.
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