Crowley's Ridge is one of the six natural geographic divisions of Arkansas which rises out of the Mississippi embayment as a relatively steep, uncultivated loessial mass. The ridge is drained by a network of headwater streams which are relatively clear with alkaline pH values and uniformly low alkalinity values. Carbon dioxide values were moderate and oxygen values were adequate. The fish species collected were basically headwater in composition. Isolated groups of characteristically upland species indicate that environmental quality of adjacent deltaic streams was better at one time.
Fulmer, Robert F. and Harp, George L.
"Fishes of Crowley's Ridge in Arkansas,"
Journal of the Arkansas Academy of Science: Vol. 31
, Article 14.
Available at: http://scholarworks.uark.edu/jaas/vol31/iss1/14