1:5M Geologic Map of Borealis (H-1) Quadrangle of Mercury
May 16, 2016

The original polygon shapefile was created in April, 1999 from older photomosaic bases as part of a larger digitization effort.  To make this dataset more useful with modern data it has been smoothed (ArcGIS PAEK smoothing method with a tolerance of 10 km) and transformed (projective transformation) to align with the 2013 Messenger basemap.  Links used to transform the data are included with this documentation.  A polyline feature class was then derived from the 
polygons and attributed with contact types.  All datasets use the slightly smaller Mercury radius of 2439000 m rather than the Mercury 2000 radius of 2439700 m.

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Data are saved in a feature dataset in Mercury_5M_Geomaps.gdb/Borealis_H01

h1660_g_PAEK10K (polygon feature class)
h1660_g_geocontacts (polyline feature class)

Projection    NORTH POLAR STEREOGRAPHIC                                                          
Zunits        NO                                                                
Units         METERS                                                            
Xshift        0.0000000000                                                      
Yshift        0.0000000000                                                      
Parameters 2439000.0000000000  2439000.0000000000                               
 0  0  0.000 /* longitude of central meridian                                   
 0  0  0.000 /* latitude of true scale                                          
0.00000 /* false easting (meters)                                       
0.00000 /* false northing (meters)                      

Separate shapefiles with the Mercury_Old GCS are located in the ...Data/Shapefiles_dd/ directory.

Coordinate systems used for each quadrangle are stored in ...Documentation/CoordinateSystems/.

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Basemaps have not been included in this download package, but the most current base using MESSENGER data is available through ArcGIS Online or can be downloaded at the following link:
http://astrogeology.usgs.gov/search/map/Mercury/Messenger/Global/Mercury_MESSENGER_MDIS_Basemap_BDR_Mosaic_Global_166m

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Below are the RGB values sampled from the scanned originals used to symbolize geologic units and saved as a layer (*.lyr) file in the directory ...Data/LayerFiles/.

GeoUnit		RGB

ps		255 178 178
psi		255 87 60
pi		255 172 79
c4		128 193 48
cp4		128 193 48
cf4		244 246 87
cr4		244 246 87
cs4		128 193 48
c3		65 188 236
cp3		65 188 236
cf3		165 231 252
c2		254 136 13
cp2		254 136 13
c1		215 81 27
cg		161 118 89

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For more information contact:
Marc Hunter
mahunter@usgs.gov
USGS Astrogeology Science Center
Flagstaff, AZ
(928)556-7220