Shallow Depressions in the Florida Coastal Plain: Karst and Pseudokarst

In Florida, shallow depressions (i.e., depressions <1-2 m in depth) on the land surface are often attributed to sinkhole development. However, it has become evident that there are at least seven different mechanisms through which these depressions can form in Florida’s geologically young cover sediments. These mechanisms include:
1. Cover-subsidence sinkholes over shallow limestone;
2. Suffosion sinkholes over shallow limestone;
3. Cover settlement over shallow shell beds;
4. Large, aeolian deflation areas that resemble “Carolina bays”;
5. Aeolian deflation depressions within dune trains;
6. Depressions that mimic landforms developed on a shallow paleosol; and
7. Depressions created by pedodiagenesis (i.e., conversion of smectite to kaolinite) in a soilforming environment.
Of these, only the first two appear to represent traditional mechanisms for sinkhole development in eogenetic karst. Cover settlement over shell beds is poorly understood and incorrectly attributed to sinkhole-development processes. Development of this type of depression is limited by cover thickness, textural, and shell content constraints. The last three mechanisms are pseudokarst features created by aeolian and soil-forming processes.
This paper presents examples of each and discusses their constraints and evidence.
Upchurch, S.B., T.M. Scott, M.C. Alfieri, and T.L. Dobecki. 2015. Shallow Depressions in the Florida Coastal Plain: Karst and Pseudokarst (abs). Abstracts with Programs, 14th Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst™, Rochester, Minnesota.