Surface Water - Alabama Department of Environmental Management

Methodology
ridges that trend in the northeast–southwest direction. Ridges are generally made of
sandstone and chert, while valleys are generally developed on limestone and shale. Springs
and caves are relatively common. Land cover is mixed and present-day forests cover about
50% of the region. The ecoregion has diverse aquatic habitat and supports a unique and
species-rich fish fauna. The Upper Cahaba River basin and eastern half of the Locust Fork
drain the Ridge and Valley (67) Ecoregion. The area has been extensively developed for
residential and commercial use.
The Southern Limestone/Dolomite Valleys and Low Rolling Hills (67f) is composed
predominantly of limestone and cherty dolomite. Landforms are mostly undulating valleys
and rounded ridges and hills, with many caves and springs. Within the Cahaba River,
headwaters of tributary streams drain the subecoregion from the east and west. They are
moderate- to low-gradient streams with bedrock, cobble, gravel, and sand substrates. Soils
vary in their productivity, and land cover includes oak-hickory and oak-pine forests,
pasture, intensive agriculture, and urban and industrial.
A distinct segment of the Southern Shale Valleys (67g) lies within the Cahaba River
drainage between 67f and 67h. The subecoregion consists of undulating to rolling valleys
and some low, rounded hills and knobs that are dominated by shale. The soils formed in
materials weathered from shale, limestone, and clays. They tend to be deep, acidic,
moderately well-drained, and slowly permeable. The steeper slopes are used for pasture or
have reverted to brush and mixed forest land. Streams within the Southern Shale Valleys
tend to be moderate- to low-gradient streams with bedrock, cobble, gravel, and sandy
substrates.
The upper Cahaba River flows through the Southern Sandstone Ridges (67h) subecoregion.
It encompasses major sandstone and shale ridges and conglomerate beds. Streams draining
this subecoregion are high-to-moderate gradient with rocky substrates.
The Southwestern Appalachians (68) contain most of the Mulberry Fork, Sipsey Fork,
and western portion of the Locust Fork of the Black Warrior River basin. Elevations range
from around 1,100’ on the northern slopes to approximately 600’ at the northern boundary
of the Fall Line Hills near Tuscaloosa. These low mountains contain a mosaic of forest
and woodland with some cropland and pasture. The mixed mesophytic forest is restricted
mostly to the deeper ravines and escarpment slopes, and the summit or tableland forests are
dominated by mixed oaks with shortleaf pine.
Two thin fingers of the Sequatchie Valley (68b) subecoregion extend south into the
upper reaches of the Mulberry Fork. It is composed mostly of limestones, dolomites, and
shales. Streams are moderate- to low-gradient with bedrock, cobble, gravel, and sandy
substrates. Springs are common.
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