AGS / Education / Geology Resources / Physiographic Regions / Arkansas River Valley / Geology
The Arkansas River Valley represents the northern extent of the Ouachita orogenic (mountain building) system in Arkansas. Once flat-lying, these Pennsylvanian sedimentary rocks have been compressed into well developed east-west trending open folds (anticlines and synclines) and faults, which gradually diminish northward into the Ozark Plateau Region.
Shaded relief map of the Arkansas River Valley. Canoe and cigar-shaped structures represent
anticlines and synclines.
Diagram showing structures in the river valley. Most of the higher elevations exposed in the
river valley are actually what is left of the center if the syncline. Nearly all of the rocks
from the surrounding anticlinal limbs have been eroded away.