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About the Maps

Origin of maps in this database

All maps in this database have been published by the United States Geological Survey under contract to the National Aeronautics and Space Administration. These maps were originally published between 1971 and 1998. The intent of this web site version of those maps is to provide a planetwide summary of the geology of the best-know planets and satellites (Mercury, Mars, and the Galilean satellites Io, Ganymede, and Callisto) for which a comprehensive set of maps exists. Venus and Europa are still in the process of being mapped. Although images of the outer plants' satellites have been obtained, they are rarely at a resolution allowing detailed geologic mapping, and therefore have not been created and published in the USGS I-map series. The Cassini mission, now on its way to Saturn, will provide much-improved images of Saturn's satellites.

Digitization of the maps

Most of the maps were layed out using traditional photo-mechanical and paste-up methods in preparation for printing. Where possible, the press-reading stable-base films were scanned.  In some cases, maps had to be digitized from paper copies.  In both cases, maps have been rectified by means of control points in order to minimize any distortions.

Map unit colors

Due to differences in the way different programs handle color, the geologic map unit colors may differ from file to file, particularly, those in the ARCView project format may differ significantly from the TIF, PDF, and Illustrator* files.

Errors

The maps reflect the knowledge in hand at the time the maps were originally made. This dataset is intended to be an archive of the geology of these bodies as it was understood at the time the maps were completed. No attempt has been made to update them based on re-analysis, new discoveries or new mission data.

Typographical and paste-up errors recognized in the published maps have been corrected, but there has been no reinterpretation of the analysis that was done by the original author(s), even where new data have shown interpretations to be dated.


Footnote

* mention of trade names is not meant to imply endorsement by the USGS, but is merely used for descriptive purposes.


Main Menu To order
hardcopy versions
of these maps
(if available)
Viewing hardcopies
of the maps
at an RPIF