Arkansas Pin

Arkansas Pin

This pin was given to me by Ron Eberhardt, formerly of TxDot. He obtained the pin at a professional meeting.

Arkansas is a state located in the Southern region of the United States. Its name is of Siouan derivation, denoting the Quapaw Indians. The state’s diverse geography ranges from the mountainous regions of the Ozark and the Ouachita Mountains, which make up the U.S. Interior Highlands, to the densely forested land in the south known as the Arkansas Timberlands, to the eastern lowlands along the Mississippi River and the Arkansas Delta. Known as “the Natural State” (thus the logo in the pin), the diverse regions of Arkansas offer residents and tourists a variety of opportunities for outdoor recreation.

Arkansas is the 29th largest in square miles and the 32nd most populous of the 50 United States. The capital and most populous city is Little Rock, located in the central portion of the state, a hub for transportation, business, culture, and government.

The Territory of Arkansas was admitted to the Union as the 25th state on June 15, 1836. Arkansas withdrew from the United States and joined the Confederate States of America during the Civil War. Upon returning to the Union, the state would continue to suffer due to its earlier reliance on slavery and the plantation economy, causing the state to fall behind economically and socially. White rural interests continued to dominate the state’s politics until the Civil Rights movement in the mid-20th century. Arkansas began to diversify its economy following WWII and now relies on its service industry as well as aircraft, poultry, steel and tourism in addition to cotton and rice.

The culture of Arkansas is observable in museums, theaters, novels, television shows, restaurants and athletic venues across the state. Despite a plethora of cultural, economic, and recreational opportunities, Arkansas is often stereotyped as a “poor, banjo-picking hillbilly” state, a reputation dating back to early accounts of the territory by frontiersmen in the early 1800s. Arkansas’s enduring image has earned the state “a special place in the American consciousness”, but it has in reality produced such prominent figures as politician and educational advocate William Fulbright, former President Bill Clinton, former NATO Supreme Allied Commander, General Wesley Clark, Walmart magnate Sam Walton, and singer-songwriter Johnny Cash.

Geology

Arkansas GeologyRocks are generally placed into 1 of 3 major categories: igneous, metamorphic, or sedimentary. Igneous rocks have solidified from molten or partly molten mineral matter. Metamorphic rocks have been altered in the solid state from some pre-existing condition in response to significant changes in temperature, pressure, or chemical environment. Sedimentary rocks are composed of particles of sediment, which are derived by the weathering and/or the erosion of pre-existing rock. Most surficial rocks in Arkansas are sedimentary, but there are some igneous rocks (with adjacent contact metamorphic rocks) and very low grade regional metamorphic rocks in Arkansas also.

A sedimentary rock consists of two components: the particles and the cement that holds them together. However, the unconsolidated sediments of eastern Arkansas are considered sedimentary rocks. Sedimentary rocks are classified as clastic (rocks made up of grains of sand, silt, and clay) or chemical (rocks made up of shell fragments, saline water deposits, and other materials that are deposited from solution). The most common clastic sedimentary rocks are shales, siltstones, and sandstones. The most common chemical sedimentary rocks are limestone and dolostone.

To understand how sedimentary rocks form, we must account for the processes that create the original particles of sediment, the mechanisms of sediment transport, the processes of deposition or precipitation of a given sediment, and what has happened to the sediment over time. By studying rocks and depositional systems (the processes by which sediments are deposited), geologists recognize that most of the sedimentary rocks in the Paleozoic Highlands of Arkansas are marine. In the southern and eastern parts of the state, the sedimentary deposits are predominantly fluvial (fresh-water processes).

The exposures of igneous rocks in Arkansas are less than 0.1 percent of the entire area of the state. Most are exposed over 15 square miles, principally in Pulaski, Saline, Hot Spring, Garland, and Pike Counties. A few small igneous dikes and sills are present outside the Ouachita region, mostly in the Arkansas Valley, and in at least one case, in the Boston Mountains. Except for some localized contact metamorphism adjacent to the larger igneous intrusions, only very low grade metamorphic rocks are present in the state.

Major physiological divisions of Arkansas

Major physiological divisions of Arkansas

Arkansas is divided into a highland area in the northwest and a lowland region in the south and east. The rocks in the highland area are dominated by well-lithified sandstones, shales, limestones, and dolostones of Paleozoic age. A thin drape of younger unconsolidated clays, sands, and gravel, termed alluvium, is often found in valley floors and associated with the streams and rivers. The sedimentary deposits of the lowlands are mainly unconsolidated clay, sand, and gravel of Quaternary age, poorly consolidated deposits of clay, sand, silt, limestone, and lignite of Tertiary age, and consolidated (to a limited extent) deposits of Cretaceous marl, chalk, limestone, sand, and gravel (see Geologic Map of Arkansas above). Download Arkansas Physiographic Province Map (subdivisions) and Arkansas Physiographic Province Map (county base).

When most of the sediments that compose the rocks in the highland region of Arkansas were being deposited, north Arkansas was a shallow south-sloping sea floor (continental shelf), the Arkansas River Valley was near the edge of the shelf, and the Ouachita area was a deep abyssal plain . An abyssal plain is the relatively smooth and deep (more than 3,000 feet below sea level) parts of the ocean floor where accumulating sediments have buried the pre-existing topography. In the late Paleozoic Era, a broad uplift domed the Ozark strata with little structural disruption. Simultaneously, a collision of two of the earth’s mobile continental plates compressed the sediments of the abyssal plain into the Ouachita Mountains. This multimillion-year-long process folded and faulted the Ouachita strata into a structurally complex mountain chain. The Arkansas River Valley area is the transition zone between the structurally simple Ozarks and the structurally complex Ouachitas with subdued characteristics in each region.

Today, the rocks of the Ozarks tilt slightly to the south and have a dendritic drainage pattern. Since shales and siltstones erode faster than sandstones and limestones, the basic topography is flat-topped mountains with stepped flanks. By contrast, the topographic expression of the Ouachitas is controlled not only by the erosional resistance of the rocks, but also by their internal structure. The strata are complexly folded and frequently faulted. The mountains are mostly east-west-trending ridges supported by erosionally resistant rocks and separated by less resistant rocks. The Arkansas River Valley is characterized by much less intensely folded and faulted strata than the Ouachita region. Erosional processes left the synclines as mountains and the anticlines as valleys.

Location: 16-F4

Advertisements