Photograph as originally submitted to this page in the Historical Marker Database www.HMdb.org. Click on photo to resize in browser. Scroll down to see metadata.

Photographer: Cosmos Mariner
Taken: June 1, 2011
Caption: Florida Geologic Site Panel (located at a kiosk near the Visitors Center)
Additional Description: Under the provisions of Chapter 377.075(4)(e)
Florida Statutes, Devil's Millhopper
has been designated a
Florida State Geologic Site Devil's Millhopper, an impressive sinkhole, primarily exposes sediments of the Upper Eocene (37 million years old) Ocala Limestone and the Lower to Middle Miocene (24 to 10 million years old) Hawthorn Group. A few feet of the Ocala Limestone can be seen at the base of the sinkhole. The Hawthorn Group phosphatic sands, clays and dolostones are approximately 105 feet thick with a few feet of undifferentiated sands comprising the surface layer. Throughout much of the state, the Hawthorn Group sediments function as water-bearing aquifers or more often as low permeability aquitards. These sediments are also extensively mined for phosphate in northern and central Florida. The sinkhole formed when sediments overlying the Ocala Limestone collapsed into cavities dissolved in the limestone by ground water. Though covered with lush vegetation, Devil's Millhopper is one of the best natural exposures of the Hawthorn Group in Florida. This sinkhole occurs within the Alachua-Lake City Karst Hills geomorphic zone of the Okeefenokee Basin District. Designated October 9, 2000
Dr. Walter Schmidt,
Florida State Geologist
Florida Geological Survey
Submitted: October 23, 2018, by Cosmos Mariner of Cape Canaveral, Florida.
Database Locator Identification Number: p450872
File Size: 2.768 Megabytes

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