Geology and Resource Assessment of Costa Rica at 1:500,000 Scale

PROJECT OVERVIEW

Conversion of the information from the original folio to a computerized
digital format was undertaken to facilitate the presentation and analysis of
earth-science data. Digital maps can be displayed at any scale or
projection, whereas a paper map has a fixed scale and projection. However,
most of the maps on this disc are not intended to be used at any scale more
detailed than 1:500,000.

A geographic information system (GIS) allows combining and overlaying of
layers for analysis of spatial relations not readily apparent in the
standard paper publication. Digital information on geology, geophysics, and
geochemistry can be combined to create useful derivative products.

HISTORY OF THE MAPS

In 1986 and 1987, the U.S. Geological Survey (USGS), the Direcci&oacuten
General de Geolog&iacutea, Minas e Hidrocarburos, and the Universidad de Costa
Rica conducted a mineral-resource assessment of the Republic of Costa Rica.
The results were published as a large 80- by 50-cm color folio (U.S.
Geological Survey and others, 1987). The 75-page document consists of maps
as well as descriptive and interpretive text in English and Spanish covering
physiographic, geologic, geochemical, geophysical, and mineral site themes
as well as a mineral-resource assessment. The following maps are present in
the original folio:

1) Physiographic base map at a scale of 1:500,000 with hypsography,
place names, and drainage.
2) Geologic map at a scale of 1:500,000.
3) Regional geophysical maps, including gravity, aeromagnetic, and
seismicity maps at various scales.
4) Mineral sites map at a scale of 1:500,000 showing mines, prospects,
and occurrences.
5) Volcanological framework of the Tilar&aacuten region important for
epithermal gold deposits at a scale of 1:100,000.
6) Rock sample locations, mining areas, and vein locations for several
parts of the country.
7) Permissive areas delineated for selected mineral deposit types.
8) Digital elevation model.

This CD-ROM contains most of the above maps; it lacks items 1 and 8 and
the seismicity and aeromagnetic maps of item 3. The linework was digitized
from preliminary and printed maps with GSMAP (Selner and Taylor, 1987), a
USGS-authored program for map editing and publishing. Conversion from GSMAP
to ARC/INFO was accomplished through the use of the GSMARC program (Green
and Selner, 1988). The arcs and polygons were tagged using Alacarte
(Wentworth and Fitzgibbon, 1991).

[Summary provided by the USGS.]