Sharon Rafferty 19980630 Version 1.0, July 07, 1998 Map Reston, Virginia U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?co_geosymb_ha742 This digital geospatial data set consists of points and lines representing symbolization of geologic structure information for the Arapahoe and Laramie-Fox Hills aquifers. The symbols were developed as part of the report in "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 geohydrologic structure information shown in (Robson and others, 1998). Procedures_Used: Geologic contacts, strike and dip symbols, and tic marks were scanned from 1:50,000 maps (Robson and other, 1998) at 200 to 800 dots per inch into a tagged image file format (TIFF, a bit-mapped file format). The TIFF's were converted to unrectified grids, ARC/INFO raster geospatial data sets, 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 State Plane projection specific to each county map. Link files were 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. Polygon coverages were created from the grids with the ARC/INFO command GRIDPOLY. Polygons were built from groups of contiguous cells having the same cell value. Labels were added to the coverages with the ARC/INFO command CREATELABELS. The labels were centered in the polygons with the ARC/ INFO command CENTROIDLABELS. An empty coverage then was created in ARC with the bnd from the polygon coverage and brought into Arcedit with an edit feature of point. The GET command was used to bring in the labels from the polygon coverage. The coverage then was saved in Arcedit and built as a point coverage. Arc: gridpoly fig2_rgrid fig2_cov Arc: createlabels fig2_cov Arc: centroidlabels fig2_cov inside Arc: create new_cov fig2_cov Arcedit: ef point Arcedit: ec new_cov Arcedit: get fig2_cov Arcedit: save new_cov Arc: build new_cov point The point coverages were attributed with the items STRIKE, DIP and TYPE. The coverages were reopened in Arcedit and label points were attributed with their strike and dip angles along with their attributes for type. Markersymbols were placed according to the angle of the strike and placed starting counterclockwise from the horizontal which is 0 degrees. Drafts of these coverages then were plotted at a scale of 1:50,000, checked against the original mylar sheets, and corrected for omissions. The coverages were appended and built into a single point 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 together for this area. The other six data sets are: ARAPBASE - structure contours on base of upper Arapahoe aquifer LFHTOP - structure contours on top of Laramie-Fox Hills aquifer LFHBASE - structure contours on base of Laramie-Fox Hills aquifer WELLS - location of wells GEO - geohydrologic unit boundaries STUDYAREA - outline of study area The following is an AML to generate a graphic of this coverage. A copy of the markerset geosymb.mrk is included with the coverages for this area. >display 9999 >map geosymb.map >mape studyarea >mapunits meters >pagesize 37 51 >mappos cen cen >clearsel >box 1.0 1.0 35 49.5 >arcs studyarea >markerset geosymb.mrk >linecolor black >markersymbol 264 >markerlayer 1 >markerangle 90 >markerlayer 2 >markerangle 90 >markerlayer 3 >markerangle 90 >markerput 2 >markersymbol 2 >resel geosymb_cov points type cn 'sd' >points geosymb_cov >textoffset .09 0 >textsize 6 pt >textfont 94021 >textcolor black >textangle 180 >pointtext geosymb_cov dip /*norotation >clearsel >markersymbol 255 >markerlayer 1 >markerangle 0 >markerlayer 2 >markerangle 0 >markercolor green >markerput 255 >resel geosymb_cov points type cn 'vb' >points geosymb_cov >clearsel >markersymbol 266 >markerangle 180 >markercolor blue >markerput 266 >resel geosymb_cov points type cn 'ob' >points geosymb_cov >textangle 310 >textoffset .09 0 >pointtext geosymb_cov dip >linecolor red >arcs geosymb_cov >clearsel >resel geosymb_cov points type cn 'hb' >markersymbol 267 >points geosymb_cov >textoffset 0 0 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 (HA-742) 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://webserver.cr.usgs.gov/frir> Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey. 1998 Current as of publication date. Complete None Planned -105.25683629 -104.58906173 40.88668006 39.28197938 none strikes dips geologic section inlandWaters none Denver, Colorado none These data are not to be used at scales greater than 1:50,000. Colorado District Chief U.S. Geological Survey mailing address

Box 25046, MS 415, Denver Federal Center

Lakewood CO 80225 USA 1-888-275-8747 303-236-4912 (wfhorak@usgs.gov) http://water.usgs.gov/GIS/browse/co_geosymb_ha742.jpg Illustration of the dataset. jpg U.S. Geological Survey dgux, 5.4R3.10, AViiON UNIX ARC/INFO version 7.0.4 Geologic strike and dips generally are from geologic maps published by the U.S. Geological Survey. Revisions to published mapping are based on field reconnaissance data. Hydrologic Atlas-746 provides description of geology and references to published mapping. Chain-node topology present There are numerous sources for the geology. Refer to U.S.G.S. HA-742 for discussion and references. Scanned lines and data points are within 0.01 inch of the original line work. U.S. Geological Survey (comp) 1998 map Hydrologic Investigations Atlas HA-742 Denver, CO U.S. Geological Survey mylar sheets 1997 1998 Robson and others (1998). See Supplemental Information 1998 Vector Point 79 String 15 Universal Transverse Mercator 13 implied implied implied implied implied coordinate pair 17.8063663684 17.8063663684 Meters North American Datum of 1983 GRS1980 6378206.4 294.98 GEOSYMB.PAT Attribute table of GEOSYMB GIS software AREA Area of polygon in coverage units (meters) Computed Positive real numbers n/a GIS software PERIMETER Perimeter of polygon in coverage units (meters) Computed Positive real numbers n/a GIS software GEOSYMB# Internal feature number Computed Sequential unique positive integer n/a GIS software GEOSYMB-ID User-assigned feature number User-defined Integer n/a GIS software STRIKE positive numbers, 0 to 360 showing alignment in right angle to the line of dip. see (Robson and others, 1998) 0 to 360 n/a see (Robson and others, 1998) DIP positive numbers, 0 to 90 showing alignment in right angle to the line of dip. see (Robson and others, 1998) 0 to 90 represents dip angle of the structural surface using positive numbers 0 to 360. see (Robson and others, 1998) TYPE Identifier for marker symbols see (Robson and others, 1998) character See Entity and Attribute Overview see (Robson and others, 1998) Item STRIKE represents positive numbers, 0 to 360 showing alignment in right angle to the line of dip. Item DIP represents dip angle of the structural surface using positive numbers 0 to 90. Item TYPE is an identifier for marker symbols representing geologic attributes. The identifiers represent the following: vb = vertical bed ob = overturned bed s = strike d = dip hb = horizontal bed > >geosymb.PAT: > >COLUMN ITEM NAME WIDTH OUTPUT TYPE N.DEC ALTERNATE NAME > 1 AREA 8 18 F 5 > 9 PERIMETER 8 18 F 5 > 17 geosymb# 4 5 B - > 21 geosymb-ID 4 5 B - > 25 STRIKE 3 3 I - > 28 DIP 2 2 I - > 30 TYPE 4 4 C - Item LINE_TYPE is an identifier for the type of graphic symbolic representation of arcs. c = cross-section [trace of geologic section shown in Robson and others, (1998)] > >geosymb.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 geosymb# 4 5 B - > 29 geosymb-ID 4 5 B - > 33 LINE_TYPE 4 4 C - > > none 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. Markerset file markerset file zipped 1 http://water.usgs.gov/GIS/dsdl/geosymb.zip Export Full coverage zipped 1 http://water.usgs.gov/GIS/dsdl/geosymb.mrk.e00.gz Export Full coverage zipped 1 http://water.usgs.gov/GIS/dsdl/geosymb.e00.gz Other Full coverage zipped 1 http://water.usgs.gov/GIS/dsdl/geosymb.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_geosymb_ha742 FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998