Why are geologic maps important?
The answer cannot be stated any better than the following:
“The first geology map was prepared to solve practical problems involving the distribution of different types of rocks at and near the Earth’s surface, and that is still the reason geologic maps are made today. Uses of geology maps first expanded into exploration for natural resources, including minerals and petroleum. As an example, during World War II, maintaining the supply of strategic minerals became so critical that geologists in the U.S. military were assigned to make geologic maps for mineral exploration.”
“Most building materials, except wood, are from various specific rocks and rock products. The suitability of rocks and unconsolidated surficial materials to support foundations is essential for construction of homes, skyscrapers, dams, bridges, or simply a road. Rocks and unconsolidated surficial materials fundamentally affect the nature of the soil cover and plant growth is related to soil type. “ (Thomas, 2004)
And don’t forget, we are all familiar with spectacular natural disasters, such as earthquakes, volcanoes, storms, and floods!
What’s in a geologic map?
The map above is a detail from a larger map, the Geologic Map of the Murfreesboro quadrangle in southwest Arkansas. This geologic map shows the rocks and alluvial deposits that are exposed at the surface. Contrasting colors are used to indicate the different rock formations and stream terraces in this area.
The yellow color illustrates alluvium deposited by the Little Missouri River and its tributaries. Alluvium consists of loose sand and gravel. This material is an important resource for road construction and other purposes.
During the Cretaceous, a shallow marine ocean covered this area and lime mud was being deposited. These deposits are represented by the greenish colors and the symbols Kt and Kto, which breaks down into K for Cretaceous, t for Trinity group, and to for Tokyo Formation. But an explosion rocked the area here during the Cretaceous. An igneous dike pushed up from deep in the earth’s crust, bringing diamonds to the surface. The blue areas represent exposures of that rare, diamond-bearing igneous rock. The largest blue circle highlights the location of Crater of Diamonds State Park. Many areas in Arkansas are unique or geologically interesting and have become preserved in our State Parks for all to enjoy! Folks from all over travel to our state to try their luck at finding diamonds just like the 4.38-carat diamond that was found recently. Where else can you do that?
So don’t be afraid to look at a geologic map! Start with a geologic map of the area around your home. If you need help figuring it out, a friendly geologist is available to help you anytime. Reach out to us at (501)296-1877 or email us at ags@arkansas.gov.
If you are interested in geologic maps published by the Survey and want to learn more about our mapping program, then visit the links provided below:
The Arkansas Geological Survey (AGS) has conducted geologic mapping since the late 1800s. The first Geologic Map of Arkansas was produced by H.D. Miser and published by the U.S. Geological Survey in 1929. In the 1960s, the agency was involved with statewide field mapping, which resulted in the publication of the Geologic Map of Arkansas in 1976 and was revised in 1993.
The AGS continues to coordinate with other agencies in acquiring supplemental funds for mapping. Starting in the early 1990s the AGS began geologic mapping at a 1:24,000 scale under the U. S. Geological Survey’s National Cooperative Geologic Mapping Program. The STATEMAP Program provides matching funds for completion of maps in various parts of the state. Present mapping is focused on the Bethesda, Batesville, Sulphur Rock, and Charlotte quadrangles in Independence County.
For a full listing of our geologic maps, please visit:
https://www.geology.arkansas.gov/maps-and-data/geologic-maps.html
Reference: Thomas, W. 2004, Meeting challenges with geologic maps: American Geological Institute Awareness Series.
Office of the State Geologist Blog 
Physical Geology instructor at UACCB here. The Sulphur Rock map completed this year is phenomenal!!!! I plan to modify my class to include this. This top quality map will allow me to teach my class about the area in a manner that they will be able to enjoy and comprehend. Many thanks for this and your super website. Sandee Steiner BS Geological Engr
Hello Professor! Thanks for the compliments and I’m so glad you can put one of our most recently published geologic maps to good use! It is just one of a series of quadrangles on that row that we published this year for STATEMAP. The others are Bethesda, Batesville, and my personal favorite, Charlotte. In case you didn’t see it on our website, the AGS has also recently mapped several additional quads north and west of those that are included in a compilation of the entire historic Batesville Manganese District at the 1:24,000 scale. It is so large we had to publish it in two parts. You can see the west part here: https://www.geology.arkansas.gov/maps-and-data/geologic_maps/DGM-AR-BMD-W-001-geologic-map-of-the-batesville-manganese-district-west-part.html; and the east part here: https://www.geology.arkansas.gov/maps-and-data/geologic_maps/DGM-AR-BMD-E-002-geologic-map-of-the-batesville-manganese-district-east-part.html.
Good luck with your class this year and let me know if you need any additional teaching materials. I can be reached at richard.hutto@arkansas.gov.
I need help with identifying 3 rocks I found near LakeTenkiller. I am told all three have the same geologic feature common in many sandstones of Oklahoma. However, in my online research, I cannot find any evidence of these anywhere in Oklahoma.
Hello Marcia! Would you be able to email me pictures of the rocks in question? corbin.cannon@arkansas.gov