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Dear FGS Friends and Customers,

I’m pleased to share with you the Summer issue of FGS News and Research. In this issue, we are highlighting new cooperative projects with two water management districts and announcing the Florida Geoscience Workgroup, an intra-agency workgroup established to foster knowledge exchange, communication, and education within DEP and the water management districts. In addition, the Florida Aquifer Vulnerability Assessment, which has been an important water-resource protection, management and planning tool, is getting an upgrade, with a larger model extent and more highly resolved GIS data layers.

I also want to call your attention to the newsletter banners, each of which reflect a geological phenomenon. In our recent Spring edition, we shared exfoliating karst, and in this issue, weathered and karstified Suwannee Limestone exposed along the river for which it was named. Many thanks for your feedback on the new GEOFACT series – we hope you continue to find it informative.

Best Regards,

Jonathan D. Arthur, Ph.D., P.G.
Director and State Geologist
Office of the Florida Geological Survey
Florida Department of Environmental Protection

In This issue Bar

•GEOFACT - Florida’s Oldest Rocks Exposed: the Avon Park Formation   More…

•FGS to Update Florida Aquifer Vulnerability Assessment More…

•FGS Cooperates with Water Management District to Install Monitor Wells   More…

•Florida Geoscience Workgroup Initiated   More…

•Education and Outreach Efforts Expand at FGS More…

•Springshed Mapping Supports Agency Needs More…

•See Previous Editions Of FGS News and Research More…

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GEOFACT Bar

Florida’s Oldest Rocks Exposed:
the Avon Park Formation

Fossil sea grass in Avon Park Formation. The oldest rocks exposed at the surface in Florida are limestones and dolostones of the Middle Eocene (48.6 – 37.2 mya) Avon Park Formation. The formation is exposed at the surface in both Levy and Citrus counties in very limited areas, but occurs in the subsurface over a large portion of the state. Where exposed, the Avon Park Formation generally consists of a fossiliferous, moldic, tan dolostone. However, in the subsurface, the Avon Park can consist of a chalky, fossiliferous limestone that can contain gypsum, chert and organics.

The Avon Park Formation was originally described by Applin and Applin (1944). They also described the Lake City Limestone, which underlies the Avon Park Formation. The Lake City Limestone and the Avon Park Formation were combined by Miller (1986) since paleontologic criteria were originally used to distinguish the two units and lithostratigraphic units cannot be defined based upon fossil assemblages per the North American Stratigraphic Code.

The Avon Park Formation is unconformably underlain by the Lower Eocene Oldsmar Formation and is overlain unconformably by the Upper Eocene Ocala Limestone. The Avon Park Formation attains a maximum thickness in excess of 1,000 feet in southern Florida and thins to approximately 500 feet near the crest of the Peninsular Arch where it crops out. It grades laterally into clastic facies to the north and west (Lisbon-Tallahatta sequence).

The Avon Park Formation contains an abundant and interesting fossil assemblage including foraminifera, mollusks, echinoids and plant fossils. Some of the more interesting fossils include leaves and nuts from terrestrial plants that suggest the Avon Park Formation was deposited, at least in part, in a nearshore environment. Some index fossils for the Avon Park Formation are the cone-shaped foraminifera Cushmania americana and the small echinoid Neolaganum dalli.

The Avon Park Formation makes-up part of the Floridan aquifer system and provides regionally important confining units. In areas where the unit is porous and permeable it also provides suitable storage space for Aquifer Storage and Recovery. The Avon Park Formation is also an important commodity for the mining industry in areas where it is close enough to the surface to be mined. This formation is an important source of both water and rock resources for Floridians. It also allows geologists an opportunity to decipher the environmental conditions that existed more than 40 million years ago as the limestone foundation of Florida was being built!

Contact person/info: Dr. Jonathan Arthur 

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FGS to update Florida Aquifer Vulnerability Assessment

FAVA poster available on website

The Florida Geological Survey  signed a Memorandum of Agreement with the Division of Water Resource Management, Source and Drinking Water Program in April of this year to produce an updated Florida Aquifer Vulnerability Assessment (FAVA). Over the years, it has been recognized that the incorporation of additional up-to-date data could improve the utility of the model. Improvements include increasing the number of model training points and resolution of data layers (evidential themes) along with revisions to extents of Florida’s major aquifer systems. Click here for more information and data on the first phase of FAVA.

The goal of the project is to provide a more comprehensive model through additional input data and to extend the model domain. For example, the Floridan aquifer system extent will be expanded to include all of South Florida. Each of the evidential themes (e.g., overburden thickness, soil hydraulic conductivity, and proximity to probable karst features) will be updated. Additionally, the FGS will reassess training point criteria and modify the input as required by the model. Upon completion of the revised FAVA model, DEP staff will work together to include other Florida aquifers.

Contact person/info: Alan Baker 

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FGS Cooperates with Northwest Florida Water
Management District to install Monitor Wells

Approximate locations of proposed wells in Leon County.

The FGS is collaborating with the Northwest Florida Water Management District (NWFWMD) to install monitor wells in support of the NWFWMD’s development of minimum flows and levels (MFLs) and long-term groundwater monitoring. New wells are required to serve as potentiometric surface measuring stations, provide lithologic data, and yield aquifer performance data.  

The first phase of this project, which started in late May and will go through September 2014, entails the construction of up to seven wells in Leon County to establish MFLs for the St. Marks River Rise, Wakulla Springs, and Sally Ward Spring. Three of these sites are expected to need both a Floridan and a surficial well, but local geology will determine the necessity of a surficial well.  Additional well construction within the District is tentatively proposed for each fiscal year through 2017/2018.

The FGS will also core these sites prior to installing monitor wells. The cores will provide valuable lithologic information to the District for identification of surficial and Floridan aquifers, as well as support ongoing and future projects. This project directly supports FGS initiatives related to potentiometric surface mapping and refined hydrogeological characterization of the region.

Contact person/info: Dave Paul  

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FGS logo.

The Florida Geological Survey is coordinating a Florida Geoscience Workgroup comprised of representatives from Water Management Districts (WMDs), DEP Divisions, and DEP District offices. The workgroup is an agency-based forum to discuss geoscience issues facing DEP and WMD program areas; fostering communication about data and research, and providing educational opportunities for geoscientists in the form of webinars.

Two meetings of the Florida Geoscience Workgroup (FGW) per year will be held via teleconference, and two educational webinars will include the workgroup as well as any interested agency parties.  The first meeting was held on May 29, 2014 and included topics related to aquifer (hydrostratigraphic) nomenclature consistency, statewide sinkhole probability mapping, and other geoscience topics and case histories of mutual interest.

All or part of the workgroup is called together as needed to consider issues of immediate concern by DEP or WMDs and provide recommendations for consideration.  The FGW also helps identify topical areas for the educational webinars.

Contact person/info: Dr. Jonathan Arthur 

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FGS display booth.

The mission of the Florida Geological Survey is to collect, interpret and provide objective, quality, geologic information about Florida.  One way we accomplish our mission is by providing outreach and education opportunities to our customers.  Throughout the year, FGS geologists participate in a variety of events designed to educate Floridians about the geology of our state.  These events range from giving talks and demonstrations at local schools to providing kiosks and displays at various venues.  The FGS also provides a week of in-house events during Earth Science Week in October.  Recent outreach events have included the following:

Leading a Hernando County water awareness workshop
Lecturing about sinkholes to a homeowner group in the Villages and to the Women’s Club of Chattahoochee
Providing a tour of the FGS facility and discussing geoscience career opportunities with a Tallahassee Community College geology class
Participating in a panel discussion for students in Florida State University’s Department of Earth, Ocean and Atmospheric Sciences
Staffing a booth and providing lectures for the Marion County Springs Festival held at Silver Springs in Ocala. 

Geoscience plays a crucial role in many important aspects of society from rising sea-levels to sinkhole activity. The Florida Geological Survey is committed to educating Floridians on the importance of geology and how geologists use their expertise for the benefit of society.

Contact person/info: Harley Means or Christopher Williams

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Photo of Troy Springs

The Florida Geological Survey and the Suwannee River Water Management District (SRWMD) have finalized an interagency agreement whereby the FGS will provide the SRWMD with springshed interpretations for five springs in the middle Suwannee River basin. The springs to be studied include Falmouth, Lafayette Blue, Peacock, Troy and Little River Springs. The project’s scope of work includes the deployment of flow meters in the spring conduits to obtain continuous flow data along with conductivity, temperature and depth information. Two dye traces will be conducted which will aim to refine Troy Spring’s springshed and determine Falmouth Spring’s interconnectivity with various other springs. The study will also determine Falmouth Spring’s area of groundwater influence and compile historical dye-trace data in the Suwannee basin.

Contact person/info: Tom Greenhalgh 

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