Recent sinkhole activity in Alabama has resulted in costly damage to highways and other structures, major pollution, and accidents. Sinkholes are divided into two categories defined as "induced" and "natural." Induced sinkholes are those related to man's activities whereas natural sinkholes are not. Induced sinkholes develop in a much shorter time-span than natural sinkholes. The development of both categories is dependent on some degree of solution of carbonate rocks. Induced sinkholes are divided into two types, those resulting from a decline in the water table due to ground-water withdrawals and those resulting from construction. It is estimated that more than 4,000 of these sinkholes, areas of subsidence, or related features have formed in Alabama since 1900. Almost all induced sinkholes occur where cavities developed in residual or other unconsolidated deposits overlying openings in carbonate rocks. Collapses forming new natural sinkholes in Alabama are rare and are comparable in size to induced sinkholes. Of the thousands of natural sinkholes on topographic maps, the earliest stage in their development is a matter of geologic and hydrologic history. The initial deformation of the land surface forming a new sinkhole can result from continuous solution of bedrock, a natural decline in the water table, or a combination of both. The first displacement in the land surface forming a natural sinkhole generally occurs in one of three ways. It occurs where roofs consisting of bedrock or of unconsolidated deposits collapse into an opening in bedrock progressively enlarged by solution. The collapse of cavities in unconsolidated deposits that have formed as a result of the downward migration of the deposits into underlying openings in bedrock is probably one of the more common modes of development. Slow subsidence resulting from solution of the upper surface of bedrock or the downward migration of unconsolidated deposits also form sinkholes in areas where the rate of subsidence exceeds the rate of deposition. Many sinkholes develop with little or no warning, others are preceded by the formation of recognizable features that can be observed on the ground and from the air. Photographs, and other remote sensing data, are useful in the location and evaluation of potential sinkhole problems along planned highway corrdors. They are also useful in the definition of potential sites of collapse where recognizable features are present. These features include sinkholes and other related openings, lineaments and other linear features or trends, water loss, and vegetative stress or anomalous vigor. This information coupled with that on geologic and topographic maps and from available water records allows an evaluation of potential highway corridors with a minimum of fieldwork. /Author/

  • Corporate Authors:

    U.S. Geological Survey

    F Street Between 18th and 19th Street, NW
    Washington, DC    20244

    Alabama State Highway Department

    11 South Union Street
    Montgomery, AL  United States  36130

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Newton, J G
  • Publication Date: 1976-1

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 83 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00139257
  • Record Type: Publication
  • Report/Paper Numbers: HPR-76 Final Rpt., FHWA-RD-M-0305
  • Contract Numbers: 930-070
  • Created Date: Sep 4 1976 12:00AM