Florida Groundwater and Hydrogeology

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

+100 ft The Florida Platform Nassau Freeport Miami The Florida platform is a miles-thick carbonate bank Warm period -300 ft Ice age CaCO 3

Precambian4.5 Bya to 500 Mya Paleozoic500 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)

Approximately 250 million years ago

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

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

Carbonate Deposition/Sedimentation Marine Calcium and Magnesium Carbonate CaCO 3 MgCO 3

Florida platform was a flooded, submarine plateau dominated by carbonate deposition FL platform CaCO 3 Between about 150 Mya and 25 Mya

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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

carbonates Prior to 24 Mya Marine Carbonates Between 150 and 25 Mya, Florida was dominated by carbonate deposition

Continental Influences

Sedimentation on the Florida Peninsula Sediments

Isolation of the Florida Peninsula Suwannee Current (similar to Gulf Stream) Georgia Channel sediments

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

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

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

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

Sediments Filling in the Georgia Channel Early Miocene (~ 24 Mya) Carried by rivers and longshore currents

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

Siliciclastics Covered the Peninsula Silicon-based

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.

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

Megalodon #MG1 Locality: Hawthorne Formation, South Carolina Age:Miocene Virtually flawless museum grade specimen. Perfect serrations, black and gray mottling Price: $ SOLD Miocene sediments are non-carbonate marine sediments

In Gainesville, Miocene clays tend to be fairly thick and, in many cases, close to the surface 13 th st.

Alfred A. Ring Park 1801 NW 23rd Boulevard—parking at Elks Lodge

The thickness of and depth to Miocene sediments varies Up to 40% phosphorus ft thick in the North-central part of state Also contains uranium OK Uranium decays to Radon

Limestone originating from the Eocene and Oligocene Epochs forms the water-bearing unit for the Floridan Aquifer. 55 – 24 million years ago Clays and Sands (Hawthorne) Siliciclastic sediments from the continent settled over the limestone beginning 24 Mya. forming the upper confining unit for the Floridan Surface Saliciclastics (sandy) Surface features were shaped primarily during the Pleistocene Generalized Florida Geology

55 – 24 million years ago Clays and Sands (low permeability) Surface Siliciclastics (sandy) (highly permeable) The Floridan aquifer is a confined aquifer. The water-bearing unit is permeable limestone. Low Permeability Confining Unit (poor water movement) Unconfined aquifer is extensive throughout the state of Florida Low permeability rock (confining) Permeability: the ease with which water moves through material

The water-bearing unit of the Floridan Aquifer is a confined, consolidated limestone formation. How does it contain and release water? The Floridan Aquifer