Abstract:
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).
Supplemental_Information:
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.