Arkansas – Geography and Geology

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Individuals in the U.S. don’t have to travel very far to find topographical change.   We are surrounded by a variety of land characteristics that give our nation a venue for diversity. For instance, many of us would be surprised to know that Arkansas is one of the most geographically diverse states in the South East part of the country.

In the northern and western part of Arkansas you will find the Highlands. In this area you will find the Ozark Plateau and the Ouachita mountains. To the south and East of Arkansas you will find the Lowlands. Arkansas can further be divided into 5 sectors: West Gulf Coast Plain, the Mississippi Alluvial Plain, the Ouachita Mountains, the Arkansas Valley, and the Ozark Plateau.


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West Gulf Coastal Plain

This area of Arkansas is located in the southeast area to central portion of the state. It is divided into three regions; forest and wetlands, the Arkansas River valley, and the Ouachita Mountains. Its surface is also divided into levels based on the rock formation.

  • Tertiary formation, which mostly consists of older rock formations, clay, and sands from the Cretaceous era.
  • Cretaceous rock formation dating back to when the waters from the Gulf of Mexico extended into Arkansas. Also, Quarternary alluvium, which are deposits from the area’s rivers.

The wetlands in the West Gulf Coastal Plains are the winter home to many ducks. As per the ANHC, an agency of the Department of Arkansas Heritage, this area is the home to hundred of rare species. The West Gulf Coastal Plain is rich in natural resources, such as gas. Many acres in this area are dedicated to farmlands and pine forests.

Ozark Plateau Region

This region consists of several plateaus: The Boston Mountains, Springfield Plateau, and Salem Plateau. It begins in Oklahoma and ends in the central part of Arkansas. As noted on the official site for Arkansas Geological Survey, the Ozark Plateau Region is hilly and densely wooded.   River gorges abound and some are up to 1,500 feet deep, created through the years by streams’ currents, cutting through the region.

The Boston Mountains are characterized by its sandstone and shales believed to have been deposited many centuries ago by streams flowing south.

The Springfield Plateau is made-up of mostly limestone and caves and sinkholes characterize this area. This area’s topography consists mostly of lesser altitude hills and gorges.

The Salem Plateau consists of dolostone and less karst. It is the lowest plateau exhibiting some elevations reaching 1400 feet above sea level.

The Ozark Plateau Region of Arkansas is definitely of breath-taking magnificence; its beauty is captured in writing by Mel White’s National Geographic article in the January 2008 issue.

Arkansas Valley

Separating the Ozark Plateau to the north and the Ouachita Mountains to the south is the Arkansas Valley. Several flat top mountains or mesas are scattered in this area, in addition to rolling hills that characterize the valley. Arkansas’ largest river, the Arkansas, cuts through this valley thus nourishing the valley’s fertile soil and the area also flaunts prairie grasses and forests.

According to the state’s geological survey, the elevations of Arkansas Valley’s are lower than that of the Ozark Plateau and Ouachita Mountains with the exception of Magazine Mountain, which is the tallest mountain in the state of Arkansas. The valley’s higher elevations represent what is left of the center of the folds or synclines.

Ouachita Mountains

Is a major range that runs east to west. This range consists of ridges and valleys from Oklahoma to mid Arkansas. This area is famous for its hot springs and their therapeutic qualities.

As per data from the official site for Arkansas Geological Survey, the Ouachita Mountain Region is known for its unique rock formations deposited and compressed in an inclined or folded manner. Its mountain formation clearly exhibiting erosion and sedimentation formed through the years.

As pointed out on the Arkansas Heritage website, at the foot of the Ouachita Mountains lies the Crater of Diamonds State Park.   As reported by the Arkansas, the Natural State Website, diamonds can still be found in a 37-acre plot. It is believed that millions of years ago, diamonds surfaced after an old volcano eroded. Today, diamonds and other precious stones can be mined.

View of Ouachita Mountains from Hot Springs Mountain Tower, Hot Springs National Park, Arkansas (Looking North).  Photo: Gary Dee, 2004.
View of Ouachita Mountains from Hot Springs Mountain Tower, Hot Springs National Park, Arkansas (Looking North). Photo: Gary Dee, 2004.

Mississippi Alluvial Plain

Most of the Mississippi River Plain is in eastern region of Arkansas. It lies along the Mississippi River and expands over a third of Arkansas. This plain is comparatively level with a few elevations as high as 100 to 300 feet tall and a couple of even higher elevations.   The plain is interrupted by a few consecutive hills from north to south and its surface is mostly made-up of unconsolidated sediments.

According to Stephen Boss from the Geology department of the University of Arkansas, the state is vulnerable to seismic activity due to its subterraneous structure and existence of several faults. Though most seismic activity in Arkansas is a result of the New Madrid fault, in the northern corner of the state, there are other faults scattered throughout Arkansas.

References Cited

Arkansas Heritage retrieved from Arkansas Heritage.com on January 4th, 2012.

Arkansas Geological Survey: Retrieved from: http://www.geology.ar.gov/home/index.htm on           January 5th, 2012.

White, Mel. “The Intimate Wild: Ozark Highlands Trail.” National Geographic (October    2008), 122-139. Retrieved from http://ngm.nationalgeographic.com/2008/10/ozark-     trail/white-text/1 on 01/04/2012

Wilderness Areas from the Official of Arkansas Department of Parks and Tourism (2010) Retrieved from http://www.arkansas.com/outdoors/hiking/areas/

The Geography of Arkansas. Information retrieved on January 4, 2012 from:           http://www.netstate.com/states/geography/ar_geography.htm

Boss, S.K. 1998, Geology of the War Eagle Quadrangle, Northwest Arkansas: A Proposal to the     United States Geological Survey Educational Mapping Program (EDMAP): Unpublished      proposal, Department of Geology, University of Arkansas, Fayetteville, AR.

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