1. Florida Groundwater and Hydrogeology

2. Groundwater provides 98% of all available freshwater 62% 21% United States Total Water Withdrawals Florida Surface Water Groundwater More than 90% of Florida’s drinking water is from groundwater

3. Florida’s Groundwater

4. The Florida Platform -300 ft The edge is defined as where the water depth is at 300 feet. 100 miles west of Tampa 3-5 miles east of Miami 30-40 miles east of St. Augustine

5. Precambian4.6 Bya to 570 Mya Paleozoic570 Mya to 248 Mya Mesozoic248 Mya to 65 Mya Cenozoic65 Mya to present Origins of the Florida Platform (Earth formation, cooling, oceans, atmosphere, life, oxygen)

6. Approximately 250 million years ago

7. Rifting phase: Creation of the Atlantic Ocean - 250 Mya Breakup of Pangaea Late Triassic, early Jurassic ~200Mya

8. Approximately 150 million years ago Stable, shallow sea floor Subject to marine sedimentation For the next several million years the area was dominated by carbonate sedimentation Late Jurassic Sedimentation: settling of particles from a fluid due to gravity

9. Na + Cl - Na + Cl - Dissolving Salt in Water NaCl Ions: stable forms of the elements that obtain charge by gaining or losing electrons. NaCl solubility In water = 350 g/L KCl solubility In water = 280 g/L CaSO 4 solubility In water = 2.4 g/L

10. The opposite of dissolution is precipitation Precipitation and Sedimentation Ions in solution come together to make a solid + charge ion - charge ion Solid

11. Sodium Chloride Sulfate Ca +2 Cl - Na + CO 3 -2 SO 4 -2 Carbonate Calcium Ocean Salts Mg 2+ Magnesium Potassium K+K+

12. Sodium Chloride Sulfate Ca +2 Cl - Na + CO 3 -2 SO 4 -2 solid Carbonate Calcium Precipitation and Carbonate Platforms Calcium and carbonate are at near saturation levels in oceans (amounts are close to a threshold for precipitation) Ca 2+ + CO 3 2- = CaCO 3

13. Corals Mollusks CaCO 3 MgCO 3 Marine Calcium and Magnesium Carbonate Carbonate Deposition/Sedimentation Foraminifera Algae

14. Calcification requires: Warm, shallow water, sunlight

15. Hermatypic Corals Photosynthetic: Consumes CO 2 Coral polyp Symbiosis Symbiosis promotes Calcium precipitation zooxantellae Precipitated CaCO 3

16. Florida platform was a flooded, submarine plateau dominated by carbonate deposition Between about 150 Mya and 25 Mya 150 25 Present Sea level Time: millions of years ago Sea level Changes FL platform CaCO 3 Between about 150 Mya and 25 Mya

17. *

18. The Eocene and Oligocene limestone forms the principal fresh water-bearing unit of the Floridan Aquifer, one of the most productive aquifer systems in the world Eocene: 55 – 34 million years ago Oligocene: 34 – 24 million years ago The Eocene and Oligocene Limestone

19. Extensive Carbonate Platform Millions of years, miles thick *

20. Continental Influences

21. Sedimentation on the Florida Peninsula Sediments

22. Suwannee Current Sandy, Clayey Sediments Isolation of the Florida Platform Georgia Channel

23. Isolation of the peninsula from continental influences allowed carbonates to build on the platform for 125 million years Fundamental change came approximately 25 million years ago

24. Lowering of Sea Levels, Interruption of Suwannee Current Suwannee Current Events of the Late Oligocene Epoch, approximately 25 Mya Raising of the Florida Platform +100 ft

25. Rejuvenation of Appalachians, increased sediment load sediments Miocene Epoch: beginning approximately 24 Mya

26. These Sediments were Silicon-based Sands, Silts, Clays, Rocks, and Rock Fragments KAlSi 3 O 8 CaAl 2 Si 2 O 8 NaAlSi 3 O 8 MgSiO 4 KAl 3 Si 3 O 10 They are typically called “siliciclastics” Feldspars Olivine Muscovite

27. Suwannee Current Sandy, Clayey Sediments Filling in the Georgia Channel Georgia Channel

28. Sediments Rising sea levels allow sediments to become suspended in water and drift over the platform

29. Sandy, Clayey Sediments These sediments confine the water in the limestone Commonly referred to as the Hawthorne Formation

30. 1.Deposition of Eocene/Oligocene Limestone (55 – 24 Mya) 2.Raising of the Florida platform 3.Lowering of sea levels, interruption of the Suwannee Current 4.Infilling of the Georgia Channel with sediments derived from Appalachian/continental erosion 5.Sea level rise, lack of Suwannee current. 6.Suspended siliciclastic sediments settle over the peninsula 7.These sediments blanket the underlying limestone forming the upper confining layer for the Floridan Aquifer. Summary

31. Sands Miocene deposits are siliciclastic: sands, silts, clays, rocks Limestone These deposits are known commonly as the Hawthorne Formation. They overlie the Eocene and Oligocene limestone deposits and form the upper confining unit for the Floridan Aquifer. Basic Florida Geology Confining unit Water-bearing unit sands, silts, clays, rock