Alabama Landscapes

Piedmont

Piedmont Upland Section

Introduction

The Piedmont Upland section in Alabama (Figure P1) occupies about 9% of the state and occurs in a triangular-shaped area of east central Alabama bounded by Verbena (Chilton County), Piedmont (Cleburne County) and Phenix City (Russell County). The upland is bordered by the Valley and Ridge Province to the northwest (Figure P2) and the Coastal Plain Province to the south.

Figure P1. Location Map of The Piedmont Upland. The broken back line separates the northern from the southern piedmont upland districts. The boundary between the Piedmont and the Valley and Ridge in Chilton and Shelby counties on the map does not match the geologic boundary between sedimentary and metamorphic rocks (see Figure VR2). The blue line shows the line of the topographic profile (Figure PD1). (Base map from Cartographic Research Lab., University of Alabama)

The Piedmont Upland (hereafter called the Piedmont) consists of a plateau that slopes from the north (where elevations are commonly above 1,000 feet) to the south, where its contact with the Coastal Plain along the Fall Line commonly occurs at about 500 feet.

Figure P2. Boundary between the Valley and Ridge (foreground) and Piedmont (background). H280, W of Sylacauga, Talladega County. (Image © Mike Neilson)

The Piedmont contains about 256,000 people, 94,000 of whom live in Auburn, Opelika and Phenix City. Population density is the lowest of all sections (~59 persons/square mile), and three counties (Coosa, Cleburne and Clay) contain fewer than 14,500 people. Race and ethnicity is about the same as the state as a whole (73% white, 24% black or African American). Two major highways run through the Piedmont: I-20, which connects Birmingham and Atlanta; and H-280, which connects Birmingham to Phenix City (Figure P1).

With high average rainfall and temperature (average annual rainfall ranges from 56 inches in Auburn to 59 inches in Ashland and average annual temperature from 63 to 60^oF) chemical weathering is effective on most of the Piedmont rocks, resulting in thick soil horizons. A characteristic small scale feature of the Piedmont is saprolite, or rotten rock, which forms where deep chemical weathering has changed the minerals present in a rock but retained the texture and structure (Figure P3).

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