Geologic Shaded Relief Map of Venezuela
1U.S. Geological Survey, Reston, VA 20192.
2Escuela Geología, Minas y Geofísica, Universidad Central de Venezuela and Fundación Venezolana de Investigaciones Sismológicas, Caracas, Venezuela.
| The geologic shaded relief map of Venezuela
was created by direct digitization of geologic and hydrologic data north
of the Orinoco River from a 1:500,000 scale paper map set. These data were
integrated with a digital geologic map of the Venezuela Guayana Shield,
also derived from 1:500,000 scale paper maps. Fault type information portrayed
on the map, including unlabeled fault types, are as depicted in the original
data sources. Geologic polygons were attributed for age, name, and lithologic
type following the Léxico Estratigráfico de Venezuela. Significant
revisions to the geology of the Cordillera de la Costa were incorporated
based on new, detailed (1:25,000 scale) geologic mapping. Geologic polygons
and fold and fault lines were draped over a shaded relief image produced
by processing 90 m (3-arc second) radar interferometric data obtained by
the space shuttle radar topography mission (SRTM). Values for null-data
areas inherent in the SRTM data set were filled by interpolation based on
surrounding data cells. The digital elevation model data was hill-shaded
using an illumination direction of 315 degrees at an angle of 65 degrees
above the horizon to produce the shaded relief image. The map projection
used is equidistant conic, with latitudes 4 and 9 degrees north as standard
parallels, and longitude 66 degrees west as the central meridian.
The data contained in this map compilation primarily was derived from 1:500,000 scale maps and arranged for presentation and use at the scale of 1:750,000. Users may zoom in to view greater detail at larger scale; however, the authors make no guarantee of the accuracy of the map representation at scales larger than 1:750,000.
|Nonsystematic misregistration of some geologic contacts and faults with topographic lineaments in the Guayana portion of the map becomes apparent with the drape of the older geologic data over the newly-available SRTM dataset. The geologic data of the Guayana area shown in this map was based on older imagery sources which contained registration and splice errors. Correction of nonsystematic misregistration errors is planned for future versions of the geologic map, and map users are encouraged to contact the authors to report inaccuracies (firstname.lastname@example.org; email@example.com).|
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of the Interior, U.S. Geological
URL: http:// pubs.usgs.gov /of/2005/1038/index.html
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Last modified: 21:11:01 Sat 12 Jan 2013
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