Geologic maps are uniquely suited to solving problems involving Earth resources, hazards, and environments. Geologic maps represent the distribution of different types of rock and surficial deposits, as well as locations of geologic structures such as faults and folds. Geologic maps are the primary source of information for various aspects of land-use planning, including the siting of buildings and transportation systems. Such maps also help identify ground-water aquifers, aid in locating water-sup-ply wells, and assist in locating potential polluting operations, such as landfills, safely away from the aquifers. They can also be used to predict earthquake, volcano, and landslide hazards, and to characterize energy and mineral resources and their extraction costs.

Geologic maps are actually four-dimensional data systems, and it is the fourth dimension of time that is crucial to assessing natural hazards and environmental or socio-economic risk. To read a geologic map is to understand not only where materials and structures are located, but also how and when these features formed.

The geologic mapper strives to understand the composition and structure of geologic materials at the Earth’s surface and at depth, and to depict observations and interpretations on maps using symbols and colors (Figure 1). Within the past 10 to 20 years, geographic information system (GIS) technology has begun to change aspects of geologic mapping by providing software tools that permit the geometry and characteristics of rock bodies and other geologic features (such as faults) to be electronically stored, displayed, queried, and analyzed in conjunction with a seemingly infinite variety of other data types.

Geologic maps are actually four-dimensional data systems, and it is the fourth dimension of time that is crucial to assessing natural hazards and environmental or socio-economic risk. To read a geo-logic map is to understand not only where materials and structures are located, but also how and when these features formed.

After:

https://geoinfo.nmt.edu/publications/maps/geologic/whatis.html https://www.usgs.gov/core-science-systems/national-cooperative-geologic-mapping-program/science/introduction-geolog-ic?