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Make a Geologic Map?
Why Make a Geologic Map?
An accurate geologic map is needed to understand the Earth’s
resources and hazards.
A geologic map provides basic data for understanding both past and present-day
processes affecting a region of the Earth. This kind of information is important
for four main reasons:
To provide geologic information that can help
to reduce death and damage caused by geologic hazards such as earthquakes
and landslides. Different
types of geologic materials can amplify shaking or even liquify
during earthquakes. Some also are more likely to produce landslides,
or they may contain natural deposits of hazardous asbestos
or mercury. A geologic map shows where these types of geologic
materials are, as well as the location of faults that might
To better find and protect or safely extract geologic
sand, metals, petroleum, even groundwater, are all important
geologic resources, but to benefit society, they first must be
found. A geologic map shows the distribution of the rocks and
sediments that are most likely to contain these resources. For
example, if you needed sand and gravel to make concrete, would
it be better to look in an area of solid granite (map unit Kgr)
or in an area of loose river deposits (map unit Qha)?
To improve our stewardship of the Earth through
informed agriculture, construction, and environmental practices. A geologic
map shows the distribution of the types of geologic materials
that are likely to produce poor soils that are unsuitable for
agriculture (for example, map unit Jsp). It also shows which
rocks will provide the safest foundations for buildings and
roads, as well as those which can help support important or endangered
To help geologists unravel the geologic history
of the region. The
relations between the geologic materials and structures shown
on the geologic map give clues about the sequence of events that
happened in the area in the past. An improved understanding of
the geologic history helps us to better understand the region's
geologic resources and hazards.
Learn more about the USGS geologic mapping