Sharon Rafferty 19980630 Version 1.0, July 20, 1998 Map Reston, Virginia U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?co_lfhtop_ha742 This digital geospatial data set consists of structure contours of the top of the Laramie-Fox Hills aquifer along the Front Range of Colorado. The U.S. Geological Survey developed this data set as part of a project described in the report, "Structure, Outcrop, and Subcrop of the Bedrock Aquifers Along the Western Margin of the Denver Basin, Colorado" (Robson and others, 1998). This data set was created to display maps of the altitude of the top of the Laramie-Fox Hills aquifer (Robson and others, 1998). Procedures_Used: Structure contours of the top of the Laramie-Fox Hills aquifer and tic marks were scanned from 1:50,000 maps (Robson and others, 1998) at 200 to 800 dots per inch. These scans then were saved into a TIFF (tagged image file format which is a bit-mapped file format). The TIFF's were converted to unrectified grids (ARC/INFO raster geospatial datasets), by the ARC/INFO command IMAGEGRID. Vector geospatial data sets, known as coverages in ARC/INFO terminology, were created from ascii files containing the latitude and longitude coordinates in degrees, minutes and seconds. These coverages were projected into a State Plane projection that was specific to each county map. From these coverages, link files were then created to help register the grids to the coverages by use of the ARC/INFO command CONTROLPOINTS. Arc: controlpoints fig2_grid fig2_lin fig2_tics nominal identity # point Registration root mean square errors of 0.005 or less were acceptable for the creation of link files. The unrectified grids were georectified with the ARC/INFO command GRIDWARP, which transforms or rubber sheets a grid along a set of links by using a first-order polynomial transformation. The grid-cell size was resampled to a larger cell size to decrease processing time for conversion to coverages. GRID: setcell 20 GRID: fig2_20grid = fig2_rgrid Line coverages were created from the georectified grids with the ARC/INFO command GRIDLINE, using a line thickness of 150 feet, a weed tolerance of 40 feet, and a default dangle of 0.7 times the thickness. GRID: fig2_cov = gridline (fig2_20grid,positive,thin,nofilter, round,noitem,150, #,40) The coverages then were built with line topology and attributed. To improve cartographic display, arcs were smoothed by splining and generalizing in Arcedit with weed tolerances ranging from 30 to 100 units. Individual coverages containing the same thematic data were plotted and checked for line accuracy and attribution. The individual coverages were then appended to form a single thematic coverage. The final coverage represents one thematic layer in maps in Robson and others (1998). This data set is one of seven digital map data sets being published for this area. The other six data sets are: ARAPBASE - structure contours on base of upper Arapahoe aquifer LFHBASE - structure contours on base of Laramie-Fox Hills and Arapahoe aquifers WELLS - location of wells GEOSYMB - point and line geologic structure information GEO - geohydrologic unit boundaries STUDYAREA - outline of study area for maps produced in HA-742 The following is an AML to generate a graphic of this coverage. map lfhtop.map mape studyarea mapunits meters pagesize 37 51 mappos cen cen clearsel box 1.0 1.0 35 49.5 arcs studyarea lineset carto linesymbol 214 linesize .02 linetype hardware linecolor red lineput 214 resel lfhtop arcs length gt 5813.285 resel lfhtop arcs dashed cn 'y' textfont 94022 textsize 7 pt textcolor red arctext lfhtop contnum # line blank /*noflip resel lfhtop arcs length lt 5814.0 resel lfhtop arcs dashed cn 'y' linesymbol 214 linesize .02 linetype hardware linecolor red lineput 214 arcs lfhtop clearsel /*PRINTING LABELS OF UNDASHED CONTOURS OF BASE lineset carto textfont 94022 textsize 7 pt linesymbol 1 linesize .02 linecolor usgsred spot 100 lineput 1 resel lfhtop arcs length gt 5813.285 resel lfhtop arcs dashed cn 'n' textcolor red arctext lfhtop contnum # line blank /*noflip /*PRINTING UNDASHED CONTOURS OF BASE clearsel linesymbol 1 linetype hardware linesize .02 linecolor red lineput 1 resel lfhtop arcs length lt 5814.0 resel lfhtop arcs dashed cn 'n' arcs lfhtop clearsel Reviews_Applied_to_Data: March 1998: 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. March 1998: Inspection of copy generated from this data set. April 1998: 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. References_Cited: Robson,S.G., Van Slyke, George, and Graham, Glenn, 1998, Structure, outcrop, and subcrop of the bedrock aquifers along the western margin of the Denver Basin, Colorado: U.S. Geological Survey Hydrologic Investigations Atlas HA-742, 5 sheets, scale 1:50,000. Available through the internet at <URL:http://rockyweb.cr.usgs.gov/frontrange/> 1998 Current as of publication date. Complete None planned. -104.96266486 -104.59900529 40.88457484 40.10504503 None aquifer structure contour inlandWaters None Front Range, Colorado Denver None. These data are not to be used at scales greater than 1:50,000. Colorado District Chief U.S. Geological Survey Water Resources Division mailing address

Box 25046, MS 415, Denver Federal Center

Denver CO 80225 USA 1-888-275-8747 303-236-2904 (wfhorak@usgs.gov) http://water.usgs.gov/GIS/browse/lfhtop.jpg Illustration of the dataset. jpg U.S. Geological Survey dgux, 5.4R3.10, AViiON UNIX ARC/INFO version 7.0.4 Procedures used to develop contours are described in Hydrologic Atlas-742 Chain-node topology present. See supplemental information. Scanned lines and data points are within 0.01 inch of original line work. n/a U.S. Geological Survey 1998 Map Hydrologic Investigations Atlas HA-742 Denver, CO USGS, WRD mylar separate 1997 publication date HA-742 Structure contours were hand drawn. Please see Robson and others (1998). See Supplemental Information 1998 Vector String 40 Universal Transverse Mercator 13 implied implied implied implied implied coordinate pair 8.645301242522 8.645301242522 Meters North American Datum of 1983 GRS1980 6378206.4 294.98 LFHTOP.AAT Attribute table of LFHTOP GIS software FNODE# Internal number of from-node Computed Sequential unique positive integer n/a GIS software TNODE# Internal number of to-node Computed Sequential unique positive integer n/a GIS software LPOLY# Internal number of poly to left of arc Computed Sequential unique positive integer n/a GIS software RPOLY# Internal number of poly to right of arc Computed Sequential unique positive integer n/a GIS software LENGTH Length of arc in coverage units Computed Positive real numbers n/a User assigned LFHTOP# Internal feature number Computed Sequential unique positive integer n/a User assigned LFHTOP-ID User-assigned feature number User-defined Integer n/a GIS software DASHED Contour line sections inferred or interpolated User-defined "y", "n" y for yes, inferred n for no, not inferred User assigned CONTNUM Altitude of top of Laramie-Fox Hills aquifer above sea level. see, (Robson and others, 1998) 100 foot intervals n/a User assigned Item DASHED is a graphical indicator to represent whether data displayed was known or inferred. y = display line as dashed (inferred) n = display line as solid (known). Item CONTNUM indicates number of feet above sea level of base of aquifer. > >LFHTOP.AAT: > >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 FNODE# 4 5 B - > 5 TNODE# 4 5 B - > 9 LPOLY# 4 5 B - > 13 RPOLY# 4 5 B - > 17 LENGTH 8 18 F 5 > 25 LFHTOP# 4 5 B - > 29 LFHTOP-ID 4 5 B - > 33 DASHED 2 2 C - > 35 CONTNUM 5 5 I - > > Not available U.S. Geological Survey Ask USGS - Water Webserver Team mailing

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Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) http://water.usgs.gov/user_feedback_form.html 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. shape file Full coverage zipped 1 http://water.usgs.gov/GIS/dsdl/lfhtop_shp.zip Export Full coverage zipped 1 http://water.usgs.gov/GIS/dsdl/lfhtop.e00.gz Other Full coverage zipped 1 http://water.usgs.gov/GIS/dsdl/lfhtop.tgz None. This dataset is provided by USGS as a public service. 20041108 U.S. Geological Survey Ask USGS -- Water Webserver Team mailing

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Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+co_lfhtop_ha742 FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998