Alternative Title

NCKRI Symposium 2: Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst



Download Full Text (2.3 MB)


University of South Florida

Publication Date

May 2013


pg(s) 273-277 A cluster of aquifer drawdown-induced sinkholes developed in eastern Hillsborough County, Florida (west-central Florida), during two major freeze events in 2010. The sinkholes resulted in millions of dollars in losses and caused us to revise our thinking about how sinkholes form in a terrain normally considered to have low sinkhole risk owing to thick, clay-rich cover. The cover material consists of the Miocene Hawthorn Group, which includes up to 120 m of interfingering expansive clay, sand and sandy clay, and carbonate strata. The lower Hawthorn Group Arcadia Formation is primarily carbonate and is up to 90 m thick. The upper Hawthorn Group Peace River Formation contains more clay and sand with minor amounts of carbonate and is up to 30 m thick. The Hawthorn Group constitutes an effective aquitard for the underlying upper Floridan aquifer (UFA), which is composed of karstic, Oligocene and Eocene limestone and dolostone. A rapid drawdown of up to 20 m in the potentiometric surface of the underlying UFA resulted in mobilization of water-saturated clays and clayey sands within the Hawthorn Group. Subsidence and possible clay consolidation resulting from dewatering and loss of support/buoyancy caused development of new sinkholes and reactivation of clay-filled sinkholes that had developed as early as the Miocene Epoch. Stable, clay-filled, relict sinkholes of apparent Miocene age discovered in an earlier investigation in the same area in 1998-1999 support the presence of clay-filled, relict sinkholes in the area. Combining information gathered from study of these modern and relict sinkholes presents evidence of sinkhole development mechanisms in the thickly covered karst of west-central Florida. Open Access - Permission by Publisher See Extended description for more information. Update @ 8:38.


1 online resource


Conference Proceeding


Conference Proceedings; Serials







Rights Statement

In Copyright

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.