Florida s Karst Geology

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1 Florida s Karst Geology Orange Creek Basin Interagency Working Group Public Workshop, November 5 th, 2015 Harley Means, P.G. Assistant State Geologist Florida Geological Survey

2 Karst Karst a type of topography that is formed on limestone, gypsum and other rocks by dissolution, and that is characterized by sinkholes caves and underground drainage (Bates and Jackson, 1987) 11/13/2015 2

acidic. The slightly acidic rainwater becomes more acidic as it moves through soil.

3 How does karst form? As rainwater falls through the atmosphere it picks up carbon dioxide and becomes slightly acidic. The slightly acidic rainwater becomes more acidic as it moves through soil. Limestone, which underlies all of Florida and parts of Georgia, is dissolved by the acidic water. This creates pore space including cavities, caves and conduits. 11/13/2015 3

4 Limestone underlies all of Florida the depth to the limestone varies. Environmental Geology of the State of Florida Rock Type CLAYEY SAND DOLOMITE GRAVEL AND COARSE SAND LIMESTONE LIMESTONE/DOLOMITE MED. FINE SAND AND SILT PEAT SANDY CLAY AND CLAY SHELL BEDS SHELLY SAND AND CLAY WATER 0 11/13/ Miles 4

5 How does the acidic water get into the rocks? 11/13/2015 5

6 Carbonate rocks are porous and permeable! 11/13/2015 6

7 Fracture pattern in Florida 11/13/2015 7

8 Enlarged fracture 11/13/2015 8

9 Karst distribution in the U.S. Florida, most productive U.S. aquifer 11/13/2015 9

10 Florida s karst features SINKHOLES Numerous caves air and water filled Over 1000 known springs 33 first magnitude springs (100cfs or more), more than any other state Sinkhole Lakes (like Orange Lake) Karst topography Winter Park Sinkhole 11/13/

11 Karst topography 11/13/

12 Distribution of karst features 11/13/

13 Because of karst we have. One of the most productive aquifer systems in the world: The Floridan aquifer system! Williams & Kuniansky, /13/

14 Aquifer vulnerability 11/13/

15 Karst topography locally Orange Lake 11/13/

16 Karst lakes Karst lakes can form when sinkhole activity creates a depression in the land surface (basin). Over time these basins can enlarge and sinkholes can coalesce to form large basins like Orange Lake. The sinkhole, or sinkholes, in the bed of the lake provide a direct connection to the underlying aquifer. Most of Florida s 7800 fresh water lakes are Karst lakes. 11/13/

17 Local geology 11/13/

18 Eocene Ocala Limestone near the surface 11/13/

19 Cross section 11/13/

Recap Karst refers to landforms that form when geologic materials near the surface dissolve over geologic time. Acidic rainwater infiltrating our limestone bedrock is responsible for dissolution.

20 Recap Karst refers to landforms that form when geologic materials near the surface dissolve over geologic time. Acidic rainwater infiltrating our limestone bedrock is responsible for dissolution. The features created by this process, called karst features, include sinkholes, springs, caves, lake basins and other solution features. Florida has large areas that were modified by karst processes. Because of karst Florida sits on top of one of the most productive aquifer systems in the world the Floridan aquifer system. Because of karst our aquifers are vulnerable to contamination from surface activities. Alachua and Marion counties have numerous karst features. This is due, in part, to the proximity of the Ocala Arch and the depth to limestone. 11/13/

Questions? http://www.dep.state.fl.us/geology/geologictopics/sinkhole.htm Harley Means, P.G.

21 Questions? Harley Means, P.G. Assistant State Geologist Florida Geological Survey 3000 Commonwealth Boulevard Tallahassee, FL Sinkhole Questions: /13/

Hydrogeology of Karst NE Wisconsin. Dr. Maureen A. Muldoon UW-Oshkosh Geology Department

Hydrogeology of Karst NE Wisconsin Dr. Maureen A. Muldoon UW-Oshkosh Geology Department WI Bedrock Outline Karst Landscapes Existing WQ Data Flow in Karst Aquifers Overview of Silurian Aquifer Water Level