Brock Gap

‘’’Brock Gap’’’ (variant Brock’s Gap) is a natural pass across Shades Mountain in Hoover, Alabama, most notable as being the location used by the South & North Railroad (S&N) to reach the Birmingham area in the late 1800s from the mineral deposits to the south, spurring economic development in the area.

Geographic description

Brock Gap is located at an elevation of 518 feet (158 meters) above mean sea level, the surrounding Shades Mountain is over 700 feet in elevation. [USGS Geographic Names Information System (GNIS), detail Brock Gap http://geonames.usgs.gov/pls/gnispublic/f?p=108:3:2295697047192191::NO::P3_FID:151699] [United States Geological Survey; 1:24,000-scale topographic map, Helena Quadrangle]

Historical rail use

John Milner was tasked by the State of Alabama in 1858 to survey a route across Shades Mountain for the S&N Railroad. The S&N was intended to connect the mineral resources south of Shades Mountain, coal, limestone, and iron ore, with the developing industries in the area of Jones Valley that would become Birmingham around the junction of the S&N Railroad and the Alabama & Chattanooga Railroad. Brock Gap was selected and the rail line north constructed between 1858 and 1871, interrupted by the Civil War. At Brock Gap, workers used nitroglycerin to blast a cut 75 feet deep through limestone bedrock. [Brock’s Gap historical marker; Birmingham-Jefferson Historical Society, South Shades Crest Road]

Current rail use

Today, the 1800s cut is actively used by the CSX Lineville Subdivision, made up of part of the former Atlanta, Birmingham and Atlantic Railway, in its route from Birmingham to Atlanta, Georgia and Florida via Manchester, Georgia. The direct successor of the S&N Railroad, the CSX S&NA South Subdivision, is carried through a more recently constructed tunnel slightly east of the 1800s cut.

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