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2004
Older Abstracts COMPARISON OF PROXY PRECIPITATION RECORDS FOR THE GULF OF MEXICO VAN BEYNEN, Philip (1), CROSS, Eric (2), VAN VLEET, Ted (2), and HOLLANDER, David (2), (1) Dept. of Environmental Science and Policy, Univ of South Florida, 4202 E. Fowler Ave, SCA 238, Tampa, FL 33620, vanbeyne@cas.usf.edu, (2) College of Marine Science, Univ of South Florida, St. Petersburg, FL 33701 2004 GSA Annual Meeting Four proxy precipitation records from around the Gulf of Mexico with decadal resolution are compared to ascertain an overall picture of changes in atmospheric circulation during the last 1200 years. The four records used in this study are from: 1) lacustrine sediments (Lake Tulane, FL), 2) tree ring index (Choctawhatchee River, FL), 3) speleothem isotopes (Brooksville Ridge Cave, FL) and 4) marine sediments (Cariaco Basin, Southern Gulf of Mexico). The types of records are quite disparate in the environmental measure used to derive climatic information: lacustrine sediments - äD of terrestrial organic matter, tree ring index - standardized ring widths, speleothem record - oxygen isotopes, and the marine basin - titanium levels. There is good agreement between all of the four records’ interpretation of how precipitation changes over this period. The proposed reason for these changes in rainfall is the latitudinal movement of the intertropical convergence zone (ITCZ) across this region. The Medieval Warm Period from 1000 to 700 yrBP was a wetter period, with the ITCZ being further north, bringing more humid air from equatorial latitudes. This period is then followed by the Little Ice Age which has a drier climate, caused by the movement of the ITCZ to the south.
CREATING A SINKHOLE GIS DATABASE: CAN ALSM DETECT SINKHOLES IN URBANIZED FLORIDA? SEALE, L. Don1, BRINKMANN, Robert2, and VACHER, H.L.1, (1) Department of Geology, University of South Florida, 4202 E. Fowler Ave, SCA 528, Tampa, FL 33620, lseale2@mail.usf.edu, (2) Department of Geography and Department of Environmental Science and Policy, University of South Florida, 4202 E. Fowler Ave, CPR 107, Tampa, FL 33620 2004 GSA Annual Meeting We applied airborne laser swath mapping (ALSM, aka LIDAR, for light detection and ranging)) to delineate depressions in Pinellas County, Florida, for the purpose of assessing whether it is possible to map remnant sinkholes in urbanized Florida karst. ALSM data, which covered all of Pinellas County (1,574 sq. km), had been collected by Geosensing Engineering and Mapping (GEM) Research Center, Gainesville, FL for the Pinellas County Government in 2000. After filtering the data to remove vegetation and buildings, we were left with more than 100 million measurements of bare-earth x,y,z coordinates. We divided these point data into manageable sizes, imported them into ESRI ArcGIS 8, and constructed a grid with 2.133-m (7-ft) spacing using the inverse-distance weighting (IDW) technique. The IDW technique easily captures subtle discrete changes in a uniform background. We found that IDW was the best technique to use in Pinellas County, due to the flat topography punctuated by sinkhole development. Contouring the grid with a 0.304-m (1-ft) contour interval produced numerous closed-contour depressions (CCDs). These apparent sinkholes, stood out in sharp contrast to the surrounding flat terrain. In order to assess accuracy, we compared the contour map with color aerial photos within a GIS. If we confirmed that a CCD was most likely a sinkhole, we converted it to a shape file and added it to a Pinellas County sinkhole GIS database. Urban development was a definite impediment to identifying remnant sinkholes.
Buildings that were filtered out created large voids in the point data.
Many swimming pools appeared as CCDs. Highly reflective surfaces produced
multi-path laser returns. Anthropogenic modifications to the land surface
disrupted the uniformity of the background signal. We conclude that, although
ALSM is a valuable tool for locating sinkholes, in general, it is certainly
best utilized in undeveloped areas.
THE NATIONAL NUMERACY NETWORK – AN OPPORTUNITY FOR GEOSCIENCE EDUCATION VACHER, H.L. and FRATESI, S.E., Geology, Univ of South Florida, 4202 E. Fowler Ave, Tampa, FL 33620, vacher@chuma1.cas.usf.edu 2004 GSA Annual Meeting In a world awash in numbers, the National Numeracy Network (NNN) envisions a society in which all citizens possess the power and habit of mind to search out quantitative information, critique it, reflect upon it, and apply it in their public, personal, and professional lives. The NNN began in 2001 when the National Council for Education and the Disciplines (Woodrow Wilson National Fellowship Foundation) brought together academic centers at Dartmouth College, The Evergreen State College, Trinity College (Conn.), and the University of Nevada – Reno for the purpose of promoting quantitative literacy (QL) across the curriculum. The NNN is now expanding to become a professional organization of individuals, educational and nonprofit institutions, professional societies, and corporations that share its vision. It will be offering charter memberships through 2005. The NNN aims to support faculty development, assessment strategies, and systemic interventions through regional and national meetings, forums, workshops, and electronic publications. The intention is to grow a network of individuals and groups that will develop a quantitatively literate society. Mathematics educators are concluding that new approaches are needed to
prepare future alumni to deal with the barrage of data that awaits them.
Among the new approaches is teaching mathematics in context, and so mathematics
educators are seeking partners with interesting context (e.g., earth and
space science). At the same time, geoscience educators are finding that
their students lack the quantitative skills to learn geoscience deeply.
When geoscience educators have workshops on how to enhance the quantitative
skills of geology students, few mathematics educators attend. Similarly,
few geologists attend QL workshops convened by mathematics educators.
The NNN, with its emphasis on networking, can break this impasse.
SALINITY PROFILES OF TRANSITION ZONES BENEATH FRESHWATER LENSES IN STRIP ISLANDS FRATESI, Sarah E. and VACHER, H.L., Department of Geology, Univ of South Florida, 4202 S. Fowler, SCA 528, Tampa, FL 33620, fratesi77@hotmail.com 2004 GSA Annual Meeting The configuration of the freshwater-seawater transition zone is traditionally treated in one dimension, the percent seawater increasing with depth according to an error function. The symmetry of the error function ensures that the 50% seawater line bisects the transition zone. As a result, the 50% seawater line represents the freshwater inventory, or the position of the interface in a lens with similar volume of fresh water but no transition zone. This is the interface which the Dupuit-Ghyben-Herzberg (DGH) theory predicts. The depth to the basement below the lens does not enter into DGH theory, because the seawater is assumed to be static. To investigate whether the symmetry of the transition zone is disrupted by the presence of a shallow basement, we used SUTRA to perform a sensitivity analysis of parameters in models of a strip-island freshwater lens with varying depths to the no-flow boundary representing basement. We found that when we move up the basement in the model, the transition zone in the center of the island is translated upward and compressed, even in cases where the transition zone is entirely above the basement. The bottom part of the transition zone is compressed more than the top part, so that the 98% seawater line moves upward more than the 50% seawater line, which in turn moves upward more than the 2% seawater line. The top of the transition zone (with less than 50% seawater) is therefore thicker than the bottom of the transition zone (with more than 50% seawater) in the no-longer-symmetric transition zone. Nevertheless, the freshwater inventory line still coincides with the 50% seawater line along the axis of the lens. Overall, then, the presence of an impermeable basement below the transition
zone affects the freshwater inventory within the lens including the transition
zone. DGH theory completely misses this effect.
INSIGHTS TO THE HYDROGEOLOGY OF THE UPPER FLORIDAN AQUIFER FROM DETAILED STUDY OF ITS MATRIX PERMEABILITY BUDD, David A., Geological Sciences, Univeristy of Colorado, 399 UCB,
Boulder, CO 80309-0399, budd@colorado.edu, FLOREA, Lee J., Department
of Geology, Univ of South Florida, Tampa, FL 33620, HUTCHINGS, W.C., HSA
Engineers and Scientists, 4019 E. Fowler Ave, Tampa, FL 33617, DEWITT,
D.J., Southwest Florida Water Mgnt District, 7601 Highway 301N, Tampa,
FL 33637, and VACHER, H.L., Univ South Florida - Tampa, 4202 E Fowler
Ave, Tampa, FL 33620-5000 2004 GSA Annual Meeting The Upper Floridan Aquifer (UFA) is a multi-porosity aquifer: double
porosity (fractured porous aquifer) downdip where it is confined; triple
porosity (karstic, fractured porous aquifer) in the updip, unconfined
region. Minipermeameter measurements at 30-cm intervals in 1210 m of core
from 8 observation wells in the confined region indicate high and highly
variable matrix permeability (<1E-14.4 to 1E-11.1 m^2). The distribution
of matrix permeability is stratiform: it correlates strongly with depositional
texture. Some grainstones and sucrosic dolomites can compete with fractures
for flow. Comparison of cumulated matrix permeability with the results
of an APT in a Suwannee Formation observation well (ROMP-20, UFA confined
region) allows calculation of the average permeability of the thin, strataform
layers of secondary permeability (i.e, where core recovery is <100%
and the flow log indicates flow is concentrated). The permeability of
these paleokarst layers and fractured lithostromes adds two orders of
magnitude to the range of permeability. Simulation (MST-3D) of solute
transport in a hypothetical aquifer storage and recovery (ASR) well with
layered heterogeneity patterned after ROMP 20 indicates that the geometry
of the ASR plume is much more appropriately thought of as a “bottle
brush” than the traditional “bubble.” Caves and springs
characterize the UFA’s unconfined region. Cave mapping shows the
caves to be laterally extensive and tabular in shape. The stratiform distribution
of matrix permeability opens the hypothesis of stratigraphic control.
Spring hydrographs do not have spiky responses to rainfalls typical of
karst springs draining Paleozoic limestones, where matrix permeability
is orders of magnitude less. The UFA’s matrix permeability apparently
provides access to storage in the huge interparticle pore volume beneath
Florida spring basins. We conclude that facies-controlled matrix permeability
may play a significant role in Cenozoic carbonate aquifers.
SPRINGFLOW HYDROGRAPHS: EOGENETIC VS. TELOGENETIC KARST 2004 GSA Annual Meeting Traditional observations and interpretations of springflow hydrographs from karst areas are from telogenetic karst (e.g., mid-continent Paleozoic limestones), where the karst has developed after the limestone has been deeply buried and lithified. Limestones of telogenetic karst have very low porosities (less than 5%) and matrix permeabilities (on the order of 10-15 – 10-18 m2). Hydrographs of springs in telogenetic karst show a prompt response to precipitation events and a rapid return to base flow conditions. Hydrograph separation reveals components that represent storage within the conduits, a network of fractures, and the epikarst. Only a very small percentage of the full volume of the aquifer appears to participate in the precipitation event because the matrix permeability is so small. Thirty-three first-magnitude springs, with mean flow in excess of 100 cfs, discharge from the eogenetic karst of Florida, where the Upper Floridan aquifer is unconfined. Interparticle porosity (20-40%) and matrix permeability (10-12 – 10-14 m2) of these Eocene and Oligocene limestones, which have not been deeply buried, are in striking contrast to those of telogenetic karst. So too are the spring hydrographs. With the exception of springs that are river-rise (flow-through) systems, springs of Florida’s eogenetic karst do not show single storm events, although they do vary according to seasonal or longer-period cycles. It appears that the huge interparticle pore volume of the aquifer mutes, and even eliminates, the spiky responses that have come to be featured in conceptualizations of karst springs. Modeling efforts that seek to put simulated hydrographs in the context
of the multi-continua that characterize karst aquifers will need to recognize
the difference between eogenetic and telogenetic karst and pay special
attention to the matrix of eogenetic karst.
GIS Investigation of Potential Karst Impacts among Proposed I-66 Alignments in Somerset, Kentucky Beverly Griffin, Lee J. Florea* 2004 National Speleological Society Annual Convention The Southern Kentucky Corridor (I-66) is a proposed interstate identified by Congress to be a high priority corridor. The ultimate construction of this interstate along any alignment will have serious consequences to the environment. The project area of this study focuses on three proposed alignments of this interstate from the terminus of the northern bypass of Somerset to Laurel County, KY. The project area contains portions of the Daniel Boone National Forest along the Cumberland Escarpment. This forest contains undeveloped woodlands and gorges along the Rockcastle River and Buck Creek. The region is highly karstified with tremendous bio-diversity. Regional geology is composed of horizontal bedded units. The lowermost is the Borden Formation of Mississippian age, a non-karstic shale/limestone. Above the Borden are several highly karstified Mississippian limestones. The uppermost Mississippian age rock is the non-karstic Pennington Shale. Numerous sandstones of Pennsylvanian age prevent karstification in the ridges. We digitized geologic maps and corridor alignments, and
used existing digital data and data created during this study to analyze
the differences among the three proposed alignments of I-66 within the
project area. We calculated impacted areas, lengths, and numbers of features
and normalized them to the total within the project area. Criteria and
weighting factors afforded a means by which to compute relative impacts
of each alignment. Based upon our results, the southernmost of the three
proposed alignments has the least potential impact to the environment;
however, the Hwy 80 alignment would utilize existing roads which have
already impacted the environment.
Morphology and Classification of Conduits in the unconfined Floridan Aquifer System of West-Central Florida Lee J. Florea*, H. L., Vacher 2004 National Speleological Society Annual Convention Conduits within the unconfined Floridan Aquifer of west-central Florida include both horizontal and vertical components. Vertical portions of conduits visually correlate to fractures, and these fractures dominate conduit directionality as shown by a collection of several Florida cave maps. Length-weighted rose diagrams of passage directions reveal a NW-SE and NE-SW pattern of conduit directions statistically similar to results found in remote sensing studies. Horizontal elements occur at consistent horizons as shown by cave surveys and observations at quarries. These patterns further demonstrate that horizontal solution features can be pervasive and laterally continuous. Their control is presently unknown but is potentially the result of some combination of lithology, fracture density, and water-table position. Conduit morphology is traditionally classified from observations
in telogenetic karst. In telogenetic karst aquifers, matrix permeability
is low, and secondary permeability is provided by fractures and bedding
planes. Classification is based upon the type of recharge to the aquifer
(allogenic or hypogenic) and whether conduits are controlled by fractures
or bedding planes. Recent observations in eogenetic karst (e.g., Bahamas)
do not fit these classifications. In eogenetic karst, matrix permeability
is high - up to four orders of magnitude greater than in telogenetic karst.
We suggest that a more appropriate classification scheme of karst would
incorporate diagenetic maturity of the rock, as well as recharge type
and fracture density. In such a scheme, conduits of the unconfined Floridan
Aquifer represent a mid-point in a range between Plio-Pleistocene karst
on young carbonate islands and Paleozoic karst in the Appalachian lowlands.
Pleistocene mixing zone caves in a carbonate eolianite peninsula, Varadero Beach, Cuba Beth Fratesi*, Lee J. Florea, Don Seale, Limaris Soto Manuel Iturralde-Vinent 2004 National Speleological Society Annual Convention Varadero beach, on the northwestern coast of Cuba, extends approximately 20 km northeast into the Straits of Florida and averages 1 km wide. North-northeasterly winds have deposited carbonate eolianites, composed primarily of bioclasts derived from the erosion of fringing coral reefs. In addition to near-beach active eolianites, the core of the peninsula is composed of late Pleistocene eolianites reaching elevations of 5-8 m. We documented notches and four caves within these eolianites. Many of the notches and all of the caves display the morphologies and distribution typical of flank margin-style caves formed in freshwater-saltwater mixing zone environments seen in carbonate eolianites of carbonate islands. One of the caves, Cueva Ambrosio, is at least partially fracture-controlled. Because of the intimate physical association of the karst with the large hotels on the peninsula, the interplay of the tourism industry and the karst features is dramatic. Some notches and possible caves have been extensively developed for use as storage closets and break rooms or converted to fountains by hotels. One flank margin cave, Cueva de Pirata, is presently used as a cabaret bar. Nearby Cueva de Musulmanes and Cueva Ambrosio are protected on an ecological preserve. These caves represent the only documented flank margin style
caves observed on Cuba thus far. The absence of an overlying paleosol-dune
package and the presence of large caves in the dune lead us to speculate
that these eolianites represent deposition during the oxygen isotope substage
5e transgression.
Conduits in the unconfined Floridan Aquifer System of West-Central Florida, Morphologic Considerations Lee Florea, H. L., Vacher 12th Symposium on the Geology of the Bahamas and other Carbonate Terrains Conduits within the unconfined Floridan Aquifer of west-central Florida include both horizontal and vertical components. Vertical portions of conduits visually correlate to fractures, and these fractures tend to be the dominant control of conduit directionality as shown by a collection of several Florida cave maps. Length-weighted rose diagrams of passage directions reveal a NW-SE and NE-SW pattern of conduit directions statistically similar to results found in remote sensing studies of photolinears. Horizontal elements occur at consistent horizons as shown by cave surveys and observations of quarry high-walls. These patterns further demonstrate that horizontal solution features can be pervasive and laterally continuous. Their control is presently unknown but is potentially the result of some combination of lithology, fracture density, and water-table position. Conduit morphology is traditionally classified from observations
in telogenetic karst. In telogenetic karst aquifers, matrix permeability
is low due to prior burial diagenesis, and secondary permeability is provided
by fractures and bedding planes associated with uplift. Classification
is based upon the type of recharge to the aquifer (allogenic or hypogenic)
and whether the conduits are controlled by fractures or bedding planes.
Recent observations in eogenetic karst (e.g., Bahamas) do not fit these
classifications. In eogenetic karst, matrix permeability is high - up
to four orders of magnitude greater than in telogenetic karst. We suggest
that a more appropriate classification scheme of karst would incorporate
diagenetic maturity of the rock, as well as the traditional recharge type
and fracture density. In such a scheme, conduits of the unconfined Floridan
Aquifer would represent a mid-point in a range between Plio-Pleistocene
karst on young carbonate islands and Paleozoic karst in the Appalachian
lowlands.
Mixing-zone caves within a Pleistocene carbonate eolianite peninsula, Varadero Beach, Cuba Limaris Soto, Lee Florea, Beth Fratesi, Don Seale Manuel Iturralde-Vinent 12th Symposium on the Geology of the Bahamas and other Carbonate Terrains Varadero beach is located on the isolated Hicacos Peninsula on the northwestern coast of Cuba. The peninsula extends approximately 20 km northeast into the Straits of Florida and averages 1 km wide. The orientation of the peninsula is sub-parallel to the impinging Gulf Stream. North-northeasterly winds have deposited carbonate eolianites, composed primarily of bioclasts derived from the erosion of fringing coral reefs. In addition to near-beach active eolianites, the core of the peninsula is composed of late Pleistocene eolianites reaching elevations of 5-8 m. The south-eastern face of these eolianites (facing the mainland of Cuba) displays intense notching. It is presumed that many of these notches originated through bio-erosion. However, some display the morphologies and distribution (beads on a string and globular morphology) typical of flank margin style caves seen in carbonate eolianites of carbonate islands, such as in the nearby Bahamas. In addition to the notches, four intact caves of flank margin style were documented. They display many of the features associated with caves formed in saltwater-freshwater mixing zone environments - laterally extensive, globular chambers in the flank of the dune with cuspate walls and dead end passages. Vertical entrances consist of what appear to be solution pits and breached bell holes. Horizontal entrances are likely formed by hillside retreat. One of the caves, Cueva Ambrosio, is at least partially fracture-controlled. Because of the intimate physical association of the karst with the large hotels on the peninsula, the interplay of the tourism industry and the karst features is dramatic. Some notches and possible caves have been extensively developed for use as storage closets and break rooms or converted to fountains by hotels. One flank margin cave, Cueva de Pirata, is presently used as a cabaret bar. Nearby Cueva de Musulmanes and Cueva Ambrosio are protected on an ecological preserve. These caves represent the only documented flank margin style caves observed on Cuba thus far. The absence of an overlying paleosol-dune package and the presence of large caves in the dune lead us to speculate that these eolianites represent deposition during the oxygen isotope substage 5e transgression.
Karst of Western Cuba: Observations, Geomorphology, and Diagenesis Don Seale, Lee Florea, Beth Fratesi, Limaris Soto Manuel Iturralde-Vinent 12th Symposium on the Geology of the Bahamas and other Carbonate Terrains In Cuba, we observed many karst features in a variety of hydrogeologic settings. These hydrogeologic settings occur in close proximity only because of the complex tectonic history of the island. We observed caves within rocks ranging from Pleistocene to Jurassic, and representing a range of diagenetic ages from eogenetic to telogenetic. Our observations are from the western one-third of the island of Cuba; however, we believe they are representative of hydrogeologic settings found throughout the island. We observed caves formed within late Pleistocene carbonate eolianites on the Hicacos Peninsula east of Matanzas. Four intact caves of flank margin style, including the partially fractured controlled Cueva Ambrosio, were documented. They display many features associated with caves formed in saltwater-freshwater mixing zone environments - laterally extensive, globular chambers in the flank of the dune with cuspate walls and dead end passages. These caves are representative of eogenetic karst, in other words they formed early in the diagenetic history of the rock when matrix permeability is high. In the Viñales region of western Cuba, we observed karstification of the massive platform deposits of the Jurassic. The Jurassic deposits are part of an allochthonous carbonate sequence composed of a tectonically complex, repeating sequence of Jurassic through Eocene thrust sheets. Many of the cave systems, such as Cueva Santo Tomás, form as fracture and bedding controlled river systems within the resistant Jurassic rocks, which stand in relief as Mogotes. These cave systems typify "continental style" tropical karst seen on islands such as Puerto Rico. These are examples of telogenetic karst, in other words they form late in the diagenetic history of the rock when matrix permeability is very low. In addition to the above-mentioned cases, we noted the presence of karst within rocks ranging between the Pleistocene and Jurassic. Of particular interest are rocks of the Miocene. The Miocene karst systems range from low elevation platform flow systems similar to Florida or the Yucatan to isolated tectonic blocks and anticlines. Examples of the prior include major groundwater aquifers in western Cuba, and the latter include complex coastal cave systems along the Matanzas-Varadero coastline.
AIR-FILLED CAVES AS AN INDICATOR OF DIRECTIONAL TRANSMISSIVITY IN THE UNCONFINED UPPER FLORIDAN AQUIFER OF WEST CENTRAL FLORIDA GSA 2003 Annual Meeting, Karst Hydrology and Geomorphology in North America Over the Past Half Century: In Honor of Derek Ford and William White FLOREA, Lee J., Department of Geology, Univ of South Florida, 4202 E. Fowler Ave. SCA 528, Tampa, FL 33620, lflorea@chuma1.cas.usf.edu and VACHER, H.L., Geology, Univ of South Florida, 4202 E. Fowler Ave, Tampa, FL 33620
Length-weighted rose diagrams of the orientations of conduits
within air-filled caves in the springsheds of Rainbow and Silver Springs
reveal preferential orientations in sub-orthogonal azimuth sets. The sets
vary regionally but generally trend NE-SW and NW-SE and conform to the
directions of photolinears found in preceding studies. The likely association
of these conduit orientations with fractures is confirmed by visual inspection
and photography in several of the caves. Strikingly, many of the rose
diagrams show that lengths are concentrated in one of the two directions,
as if dissolution has selected one direction over the other, although
the particular selection and its direction vary across the study area.
Because the fracture systems that ultimately control the direction of
conduits within the cave systems extend below the present water level,
we hypothesize that similar patterns apply in the phreatic zone and account
for directional transmissivities found in a recent modeling study of the
Upper Floridan aquifer in the area.
HOLOCENE SEDIMENTATION AND BEDROCK ALTERATION IN A BREACHED FLANK MARGIN CAVE GSA 2003 Annual Meeting, Karst Hydrology and Geomorphology in North America Over the Past Half Century: In Honor of Derek Ford and William White FLOREA, Lee J., Department of Geology, Univ of South Florida, 4202 E. Fowler Ave. SCA 528, Tampa, FL 33620, lflorea@chuma1.cas.usf.edu and MYLROIE, John E., Geosciences, Mississippi State Univ, PO Box 5448, Mississippi State, MS 39762, mylroie@geosci.msstate.edu
DOLINE AND AQUIFER CHARACTERISTICS WITHIN HERNANDO, PASCO, & NORTHERN HILLSBOROUGH COUNTIES, FLORIDA GSA 2003 Annual Meeting, Karst Hydrology and Geomorphology in North America Over the Past Half Century: In Honor of Derek Ford and William White ARMSTRONG, Brian1, COLLAZOS, Alexandra2, MALLAMS, Jerry L.1, and CHAN, Doreen1, (1) Geology, University of South Florida, Tampa, FL 33620, jerry.mallams@swfwmd.state.fl.us, (2) Parsons Brinckerhoff, Tampa, FL 33607
The Upper Floridan aquifer is a limestone and dolomite aquifer approximately 300 meters to 450 meters thick, containing numerous sinkhole and karst features. Water supplies in the area are provided almost exclusively by the Upper Floridan aquifer. Hydraulic conductivities in the aquifer may vary by three orders of magnitude in the study area. The aquifer has been extensively subjected to karst activity, and the intensity of this activity is controlled largely by the distance of the aquifer from land surface, and the thickness and continuity of the clay confining unit overlying the Upper Floridan. Using depression data derived from U.S. Geological Survey (USGS) maps, doline densities (DD) were calculated over the study area, and doline-area ratios (RD) were generated and compiled by county, physiographic province, and model-derived Kx zones. Results from these analyses indicate that areas of high DD coincide with northern portions of the study area where aquifer confinement is poor. Values of RD calculated by county also support the observation of increased karst activity in the north. Of particular significance, however, are the results indicating a positive linear correlation between RD and model-derived values of Kx (r2=0.97). These results may provide a useful technique for ground-water modelers to estimate regional-scale values of hydraulic conductivity or other hydraulic properties.
SINKHOLES OF WEST-CENTRAL FLORIDA – THE HUMAN DIMENSION GSA 2003 Annual Meeting, Karst Hydrology and Geomorphology in North America Over the Past Half Century: In Honor of Derek Ford and William White BRINKMANN, Robert, Department of Geography and Department of Environmental Science and Policy, Univ of South Florida, CPR 107, Tampa, FL 33620, rbrinkmn@chuma1.cas.usf.edu, FLOREA, Lee J., Department of Geology, Univ of South Florida, Tampa, FL 33620, VACHER, H.L., Univ South Florida - Tampa, 4202 E Fowler Ave, Tampa, FL 33620-5000, and WILSON, Kelly, Department of Environmental Science and Policy, Univ of South Florida, Tampa, FL 33620 In west-central Florida, where the Floridan aquifer is largely unconfined, the landscape is dominated by sinkholes, the aquifer is notably triply porous, and the environment is enriched by first-magnitude springs. Although the springs and triple porosity are being studied vigorously by state agencies, it is the occurrence of sinkholes that has caught the attention of the public and media. Human interaction with the landscape has increased as the population has grown and as sinkhole processes are exacerbated by human activities. Formed (and forming) in limestones typically mantled by young marine and eolian sands, the sinkholes are cover-collapse and cover-subsidence dolines formed as the sand falls or ravels into limestone voids. With the development of large urban and suburban populations in the region, particularly around active sinkhole regions of Orlando and Tampa, there have been unnaturally large variations in water levels, and these have impacted ground stability. Sinkhole damage to homes is common and distinctly regional. Insurance issues associated with property damage due to subtle subsidence are highly controversial and have led to a rash of lawsuits and the development of law firms specializing in sinkhole claims. Sinkhole mapping is problematic in the urbanized areas. Many sinkholes have never been mapped because they have been filled as the sprawl has expanded. Moreover, unknown numbers of sinkholes are below the resolution of standard topographic maps and reveal themselves only because of cracks and unfitting doors in buildings affected by subsiding ground. Because of the multiple possible causes of the subsidence, insurance and, hence, legal issues have spawned a geological industry specializing in post-subsidence site investigations. Although the cause of subsidence at many sites is clear cut, there are many for which professional geologists representing insurance companies disagree with professional geologists representing homeowners.
CHARACTERISTICS AND DEVELOPMENT OF SHALLOW SOLUTION FEATURES IN THINLY MANTLED KARST, ALACHUA COUNTY, FLORIDA GSA 2003 Annual Meeting, Karst Hydrology and Geomorphology in North America Over the Past Half Century: In Honor of Derek Ford and William White LAFRENZ, W. Bruce1, BULMER, William H.1, and O'NEAL-CALDWELL, Marianne2, (1) Hartman & Associates, Inc, 201 E. Pine St, Suite 1000, Orlando, FL 32801, wbl@consulthai.com, (2) Department of Geology, Univ of South Florida, 4202 E. Fowler Ave, SCA 528, Tampa, FL 32620
We identified characteristics that suggested that karst features had formed at several different times as the landscape evolved. Many small (<5 m diameter) sediment-filled solution features penetrate the upper 5 to 8 m of the limestone, but analogous depressions are not evident on unexcavated landscape of adjacent properties. Most are conical and irregular in profile and many have coalesced into small compound solution depressions. In contrast, a smaller number of discrete, shallow solution pipes exhibit a well-formed, smooth-walled, elliptical morphology that may indicate more recent development. Where visible, shallow solution features terminate in a zone of horizontal solution cavities and solution widening is present only above and within the zone of horizontal cavities. Larger, deeper coalesced dolines and solution-widened fractures appeared to interfere, in some locations, with development of the shallow horizontal solution cavities. The deeper coalesced dolines typically penetrate below the depth of excavation, are much larger, and are comparatively widely spaced. Upchurch (2002) described evidence of vertical conduits carrying surface drainage from upland terrains into the Floridan aquifer at the Cody scarp. The widely spaced, larger, coalesced dolines may be remnants of that process. We interpret the karst features in western Alachua County as a record of episodic development influenced initially by allogenic recharge from the siliciclastic uplands bounded by the retreating Cody scarp followed by more recent development of horizontal cavities and shallow solution pipes in a zone of transition between the scarp and a mature karst plain. Smaller solution pipes that terminate in or above the horizontal cavities appear to be more recently developed. Upchurch, S.B., 2002, Hydrogeochemistry of a Karst Escarpment, in Martin, J.B., Wicks, C.M., and Sasowsky, I.D., eds, Hydrogeology and Biology of Post-Paleozoic Carbonate Aquifers: Karst Waters Institute SP 7, p. 205-211.
EFFECT OF SEM PRESERVATION TECHNIQUES ON BIOFILM APPEARANCE, DISTRIBUTION, AND HETEROGENEITY GSA 2003 Annual Meeting FRATESI, Sarah E.1, LYNCH, F. Leo2, KIRKLAND, Brenda L.1, and BROWN, Lewis R.3, (1) Department of Geosciences, Mississippi State Univ, Mississippi State, MS 39762, fratesi77@hotmail.com, (2) Department of Geosciences, Mississippi State Univ, MS State, MS 39762, (3) Department of Biological Sciences, Mississippi State Univ, Mississippi State, MS 39762
THE FLOATING LITHOSPHERE -- A SET OF SPREADSHEET MODULES TO PROMOTE GEOLOGICAL NUMERACY GSA 2003 Annual Meeting HARDEN, J.A. and VACHER, H.L., Geology, Univ of South Florida, 4202 E. Fowler Ave, Tampa, FL 33620, jaharden@mail.usf.edu Courses in quantitative literacy (QL) or quantitative reasoning
(QR) are being developed at numerous colleges and universities. A theme
of these efforts is Math Across the Curriculum (MAC). MAC provides an
opportunity to promote earth-science literacy (ESL) via Geological Numeracy,
the intersection of QL (or QR) with geological content. We are developing
geological-numeracy spreadsheet modules that enhance QL and ESL simultaneously.
The various sets of modules feature benchmark issues that are appropriate
for courses in the history of mathematics and/or science, as well as various
QL/QR and geology courses. “The Floating Lithosphere”, on isostasy,
consists of four PowerPoint/Excel modules. Each module is intended to
engage students for 1-3 hours in a self-paced lab or homework environment.
The first module explores geological hydrostatics in terms of pressures
and depth of compensation. The second recasts the problem using buoyancy
forces and the Archimedes Principle. The third focuses on the depth of
compensation in the classic Woollard intercontinental cross section. The
fourth adds gravity to the cross section, introducing free-air and Bouguer
calculations via forward modeling. The modules emphasize weighted averages,
logic functions, and rearranging equations to produce spreadsheet formulas.
ESL concepts are pressure, buoyancy, gravity, and the visual image of
mountain provinces with roots. Although the mathematics is not difficult,
the higher-order thinking is challenging. We are seeking collaborators
for classroom-testing and assessment of these and similar spreadsheet-based
modules. DIVING THE DEATH-TRAP SYSTEM, PULASKI COUNTY, KENTUCKY JASON GULLEY, Subsurface Exploration Services, LEE J. FLOREA, Department of Geology, University of South Florida Exploration and survey of the Sinking Valley Death Trap
System began in the 1970's with efforts by the Dayton Area Speleological
Society and Miami Valley Grottos to map a series of hydrologically connected
caves in Pulaski County, Kentucky. Large caves mapped by these grottos
in Sinking Valley include: Short Creek, Price Valley, Ranch, Big Sink,
Logan-Greensnake, and Baker. Several of these caves consist of dry and
hydrologically active trunk passages typically ten feet high and 30-40
foot wide. Frequently encountered sumps stymied exploration in the 1970's
and 80's. In 2000, sump divers dove the main resurgence of Sinking Valley
at Short Creek, discovering about a quarter of a mile of air-filled passage
beyond a 250-foot long sump where a second sump was encountered. Divers
are still searching for a connection between this sump and a nearby segment
of the system. After a three-year hiatus from the project, sump divers
are again exploring the system in earnest. Diving the upstream sump of
Price Valley Cave yielded nearly 3,000 feet of underwater passage and
1,000 feet of dry cave before encountering another sump. Exploration is
ongoing with several dives into the 32-mi2 karst aquifer taking place
each week. Recent mapping and re-mapping in the Sinking Valley Death Trap
System include over 18,000 feet of segmented river passage.
KARST OCCURENCE AND SINKHOLE GIS COVERAGES FOR KENTUCKY RANDY PALOR1, LEE FLOREA2, MICHAEL CAUDILL1, JIN CURRENS1 (1)Kentucky Geological Survey, 228 Mining and Minerals Resources Building Lexington, KY 40503 (2)Kentucky Speleological Survey, Inc., 228 Mining and Minerals Resources Building Lexington, KY 40503 Growing interest and need for better karst maps for Kentucky
has prompted the development of digital karst data. The Kentucky Geological
Survey (through a published 30 60 arcminute karst groundwater basin map
series in cooperation with the Kentucky Division of Water) and the Kentucky
Speleological Survey (through a digital karst feature database) have independently
collected and archived karst data for the past several years. Present
publications based upon these data and improved by current digital geologic
mapping techniques at the Kentucky Geological Survey include a Karst Occurrence
map of Kentucky (depicting regions with potential for karst development)
and a digital sinkhole coverage for Kentucky (consisting of karst related
topographic depression polygons). These maps are an important foundation
for further work and can provide an important resource for those working
in karst prone areas of the state.
SOMERSET NORTHERN BYPASS KARST GIS NSS 2003 Convention LEE FLOREA, University of South Florida; JASON GULLEY, Subsurface Exploration Services; LARRY SIMPSON, National Speleological Society The I-66 Special Project of the National Speleological Society was formed to study and document potential impacts of the construction of an interstate highway (I-66) across the karstlands of Southern Kentucky. The present project focuses on an independent utility bypass of Somerset, KY designed to serve as a segment of I-66. In the fall of 2001, the Kentucky Transportation Cabinet began the project planning phase and presented potential alternatives in April, 2002. The corridor is along the Cumberland Escarpment; host to several rare and sensitive species. A karst GIS was developed for analysis using ArcView 3.2A
software. Vector files used include: Corridor and alternates, urban areas,
suburban areas, woodlands, streams, rivers, wetlands, sinkholes, cave
entrances, springs, conduit probability polygons, flowpaths, karst occurrence.
Raster images included USGS 7.5-minute topographic and geologic maps,
and Digital Orthographic Quarter Quadrangle aerial photography. Forty-eight
(48) karst features were documented during the study within 13 karst aquifers
contained in 10 surface watersheds. Of these karst features 28 were springs,
four of which serve as headwaters of major streams. A coverage of karst
occurrence was developed subdividing the corridor into 10 land units,
8 of which are karstic. The corridor covers approximately 46km2, 79.2%
of which is karstic. Of this karstic land, 48.4% is sinkhole plain. It
is clear from this study, that the Somerset Northern Bypass is planned
within a highly karstic area. In any karst region, development should
proceed with an aquifer scale approach. Environmental studies should proceed
using ecosystem style measurement criteria.
DENSITY OF THE EARTH -- A SET OF COORDINATED SPREADSHEET MODULES TO PROMOTE QUANTITATIVE LITERACY IN GEOLOGICAL CONTEXT GSA 2002 Annual Meeting VACHER, H.L. and HARDEN, Judy A., Geology, Univ of South Florida, 4202 E. Fowler Ave, Tampa, FL 33620, vacher@chuma1.cas.usf.edu Quantitative literacy (QL), or numeracy, is the problem-solving habit of mind with which one applies mathematical reasoning and skills to analysis in nontechnical context (see Mathematics and Democracy by Lynn Steen et al., online at www.woodrow.org/nced). Geological numeracy is the intersection of QL and earth science content. We are developing geological-numeracy spreadsheet modules to help bring QL into earth science courses, and earth science content into QL courses. Of particular interest are courses in the history of mathematics and/or science. Our first set of modules, Density of the Earth, illustrates how we link spreadsheet problems to a theme involving a milestone in the understanding of Earth, space and/or time. The central module of the set aims to illustrate Polya's
classic problem-solving heuristic (George Polya, How to Solve It, Princeton
U. Press, 1959) and invokes a strategy adapting breakthroughs by Erastothenes,
Galileo, Newton and Cavendish. A key linked module works with GPS data
at ends of a 50-m tape (for Earth's circumference, then Earth's volume)
and travel times of Florida oranges dropped off buildings (for g, then
Earth's mass). This module exposes the QL pitfall of calculating after
averaging vs. averaging after calculating. Other linked modules include
calculation of rock density from mineral composition, specific weights
and porosity, and calculation of Earth density from density variation
with depth in Earth. Quantitative content of the set of modules includes
weighted averages, circle formulas, the concept that an integral is a
sum, and most importantly, rearranging equations to produce spreadsheet
formulas.
THE ALUMNI NETWORK: FORGING CONNECTIONS BETWEEN THE USF GEOLOGY DEPARTMENT
AND THE PROFESSIONAL COMMUNITY GSA 2002 Annual Meeting RODRÍGUEZ, Eileen, Univ of South Florida, 1101 Channelside Drive, Suite 210, Tampa, FL 33602, erodrigu@coba.usf.edu, BRETNALL, Robert E., HSW Engineering, Inc, 3820 Northdale Blvd, Suite 210B, Tampa, FL 33624, DEWITT, David J., Southwest Florida Water Management District, 7601 Hwy. 301 North, Tampa, FL 33637, and VACHER, H.L., Geology, Univ of South Florida, 4202 E. Fowler Ave, Tampa, FL 33620 The University of South Florida (USF) Geology Alumni Society (GAS) provides opportunities for USF geology students to network with professional geologists in the Tampa Bay community and, increasingly, in the State. Florida’s geological workforce is mainly in hydrogeology and environmental geology, including coastal geology -historically fields of concentration in the USF geology graduate program. GAS activities include an annual GeoExpo where students meet with working geologists and observe geological equipment in operation, and an annual Job Fair where students network with prospective employers. In addition, the GAS holds an annual fundraising banquet, with proceeds going to a GAS-originated endowment for fellowships to graduate students who are honored at the banquet. At its 2002 GeoExpo, the GAS inaugurated an on-campus GeoPark, which the Department will use as a field site supporting hydrogeology and geophysics courses. The GAS plays a proactive role in the Department's professional
masters degree (PMD) program: the hydrogeology internship-track program.
Students in the PMD program conduct an internship masters project funded
and supervised by a Florida Professional Geologist (PG). Each semester,
the GAS sponsors an Internship Symposium, where students present their
projects to the community at a dinner event at the Tampa offices of the
Southwest Florida Water Management District. Since 1997, when the GAS
came into existence, two-thirds of the students who have graduated from
the PMD program conducted their internship project under the supervision
of a PG who is a USF alum.
DETECTION OF ROME TROUGH TECTONICS BY QUATERNARY KARSTIFICATION: PULASKI COUNTY, KENTUCKY SEGSA and NCGSA 2002 Joint Annual Meeting FLOREA, Lee John, Kentucky Speleological Survey, Inc, The Kentucky Geol Survey, Univ of Kentucky, 228 Mining and Mineral Resources Building, Lexington, KY 40503, mr_chaos@hotmail.com Quaternary karstification of Mississippian age carbonates
in southern Pulaski County, Kentucky is extensive. Exploration and study
of several cave systems in Pulaski County has revealed a high dependence
upon geological structure. The spatial location and orientation of the
passages and flow paths within Jugornot Cave are independent of surface
drainage patterns and continue the trend found in sections of the Coral
Cave System. This relationship is shown in sections of several other regional
caves. Photographic, statistical, geologic, and seismic evidence gathered
from within Jugornot and other regional caves as well as nearby surface
features supports the hypothesis that regional speleogenesis has been
influenced by faulting. Further evidence suggests this faulting is related
to the Rome Trough structure formed during Iapetan rifting in the Late
Precambrian to Middle Cambrian. Fractures and lineaments generated by
minor reactivation of this fault system have propagated upward through
Mississippian and Pennsylvanian strata as fracture swarming. To date 5km
of passage have been mapped in Jugornot Cave with a vertical span of 81m.
Evidence gathered from this study confirms the presence of the Burnside
Lineament previously hypothesized by magnetic anomaly data. Surface and
subsurface data from this lineament extends in a 3km band spanning a linear
distance of more than 20km at an orientation of approximately 65 degrees.
Structural, depositional, and geophysical evidence points toward three
sub-parallel right-lateral oblique-slip faults in the Precambrian and
Cambrian strata of Pulaski County, including below the Burnside Lineament,
related to Rome Trough tectonism. |
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Karst Research Group, University of
South Florida, 4202 E. Fowler Avenue SCA 528, Tampa, FL 33620 -- Phone
(813) 974-8754, Fax (813) 974-2654
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Web site maintained by Lee Florea.
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