Geology and Resource Assessment of the Venezuelan ... - USGS

CAUTIONS RELATING TO USE OF THE MAPS
One of the advantages of digital maps is the ability to change the map scale.
However, the users of this disc should respect the intentions of the authors and
recognize certain limitations of digital maps. The Venezuelan MF series maps on this
disc are intended to be used at a scale of 1:500,000; they are not intended to be used at
a more detailed (larger) scale. A Venezuela 2°x3° degree quadrangle measures about
17 inches high by 26 inches wide at 1:500,000 scale.
The "quadrangle" maps in this publication cover somewhat more or less than
2°x3° depending on the specific map. For instance, the Guri map (Cox and others,
1993) contains all of the Guri quadrangle and the southern part of the Tucupita
quadrangle. The entire study area in the southeast part of Venezuela, known as the
Venezuelan Guayana Shield, is about 36 inches tall at 1:1 million scale, which is the
published scale for Bulletin 2062 (USGS and Corporación Venezolana de Guayana,
Técnica Minera, C.A., 1993).
Furthermore, the geologic map is primarily a bedrock map, which depicts
geologic materials present beneath the soil or relatively thin mantles of surficial
deposits, not necessarily the surficial materials themselves. Indeed, the study area
contains so much surficial cover and standing water that much of the mapping was
accomplished with geophysical methods as opposed to directly examining rock
outcrops.