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SESSION NO. 18 enable us to determine the spatial distribution of the producing oil fields and the frequency of their occurrence in the given distance margin. Identifying the source rocks in this 17km window will enhance the success rate of oil exploration in Sumatra and throughout the Sundaland craton. SESSION NO. 18, 1:30 PM Thursday, 2 May 2013 T2. Applications of Near-Surface Geophysics (Posters) Schneider Hall, Courtyard 18-1 BTH 7 Van Dam, Remke L. [218657] CHARACTERIZATION OF LARGE-SCALE GLACIOTECTONIC DEFORMATION IN THE LUDINGTON RIDGE, MICHIGAN, USING ELECTRICAL GEOPHYSICAL METHODS VAN DAM, Remke L., Department of Geological Sciences, Michigan State University, 206 Natural Science Building, East Lansing, MI 48824, rvd@msu.edu and AYLSWORTH, Robert L., Ingrain, Inc, 3733 Westheimer Rd., 2nd Floor, Houston, TX 77027 A bluff along the eastern shore of Lake Michigan south of Ludington contains Late Wisconsin deformation structures. Differential loading associated with a glacial re-advance caused glaciolacustrine loamy material to deform into several narrow anticlinal structures that rise from below beach level to near the top of the nearly 50 m high bluff. The anticlines separate broad synclines that control local ground water flow and impact bluff stability. The objective of this study was to characterize the orientation and lateral extent of the structures beneath the NW-SE trending ridge. We used different galvanic electrical resistivity methods that exploit the large electrical contrast between the glaciolacustrine loams and overlying coarse sandy outwash material. Electrical resistivity methods have long been part of the geophysical tool set. Recent advances, including the availability of multi-electrode systems and advanced data processing software, have made electrical resistivity tomography (ERT) a popular tool to obtain 2D models of subsurface resistivity. In this study, vertical electrical soundings (VES) were combined with borehole logs and lab-derived petrophysical relationships to characterize the site stratigraphy. Constant-spread traverses (CST) and ERT data were then used to map the spatial extent of the deformation structures. Field, lab, and modeling results presented in this work identify various strengths and limitations of electrical resistivity methods for the characterization of deformation structures in general and glaciotectonic landforms in particular. 18-2 BTH 8 Maike, Christopher [218606] SUBSURFACE GEOPHYSICAL PROFILING OF THE OAK OPENINGS SAND RIDGE MAIKE, Christopher1 , FUGATE, Joseph M. 2 , KRANTZ, David E. 3 , STIERMAN, Donald4 , LIU, Xiuju5 , BROTHERS, Candice E. 6 , and SEARS, Lindsey6 , (1) Environmental Sciences (Geology), University of Toledo, 1760 N. Westwood Ave, Apt L, Toledo, OH 43607, ccgeology@gmail.com, (2) Environmental Sciences (Geology), University of Toledo, 629 N. Reynolds Rd, Apt 20, Toledo, OH 43615, (3) Department of Environmental Sciences, University of Toledo, 2801 West Bancroft Street MS604, Toledo, OH 43606, (4) Environmental Sciences, University of Toledo, 2801 W. Bancroft St. #604, Toledo, OH 43606, (5) Department of Environmental Sciences, University of Toledo, 2801 West Bancroft St, MS#604, Toledo, OH 43606, (6) Department of Environmental Sciences, University of Toledo, 2801 W. Bancroft St, Toledo, OH 43606 The Oak Openings Preserve extends from northwest Ohio into southeast Michigan. This unique area was shaped through glacial and glaciolacustrine processes to create a diversity of ecosystems including oak savannah, wet prairie, and sand barrens. The Oak Openings Sand Ridge is the primary landform within the preserve, and contrasts with the surrounding lake-bed plain to create these unique environments. Evidence suggests that the sand ridge was once a barrier bar system that developed during pro-glacial lakes Warren and Wayne. The area is home to more than a third of Ohio’s rare plant species and is on the Nature Conservancy’s list of Last Great Places. The environment that created these ecosystems is rare, and it is essential to understand the underlying geology and aquifer system in support of habitat restoration. Data was collected at Irwin Prairie, Shaffer Road, and Kitty Todd Nature Preserve which are all located just west of Toledo, Ohio. The data consisted of ground penetrating radar (GPR) and electrical resistivity transects, and a vibracore for ground truth. The stratigraphy at Irwin Prairie consists of a thick sand layer at the surface with a glacial till layer at a depth of 3.25m which acts as an aquitard. Irwin Prairie appears to be located in the back-barrier portion of the barrier bar complex. GPR data from Kitty Todd Nature Preserve indicates that it is situated on the ridge of the barrier bar complex, which is evidenced by large-scale sigmoidal bedding of a progradational spit. In contrast, the depositional environment of the Shaffer Road site is a shoreface that is prograding basinward, to the northeast. The modern investigative techniques allowed imaging of the subsurface to interpret the depositional environments and to characterize the surficial aquifer that created the physical setting of this unique and valuable ecosystem. 18-3 BTH 9 Jol, Harry M. [218793] STRATIGRAPHY OF COASTAL AEOLIAN SAND DUNES: MODELS VS. GPR IMAGING JOL, Harry M., Department of Geography and Anthropology, University of Wisconsin- Eau Claire, Eau Claire, WI 54702, jolhm@uwec.edu The genesis and internal stratigraphy of coastal aeolian sand dunes are often inferred from models based on dune geometry and sedimentary processes, shallow trenches, natural scours, and/or interpretations of ancient strata. However, there is some difficulty of directly observing the stratigraphy of aeolian landforms, particularly in large dunes, and those containing complex bedforms and/or multiple reactivation surfaces. The distinctive nature of the aeolian environment, that is the relative homogeneity of sediments (quartzitic sand), provides a unique opportunity for ground penetrating radar (GPR) to reveal subsurface details. The noninvasive GPR method provides near-surface, high-resolution, near continuous profiles within these increasingly sensitive, depositional settings. PulseEKKO 100 and 1000 GPR acquisition systems were used with 200, 400 and 1000 volt transmitters. Step size and antennae separation varied depending on antennae frequency and site conditions. Each trace was vertically stacked and the digital profiles were processed and plotted using pulseEKKO software. The transects were topographically corrected based on laser level surveys. To measure depth, near surface velocity measurements were calculated from common midpoint (CMP) surveys. The application of radar stratigraphic analysis on the collected GPR data provided the framework to investigate both lateral and vertical stratigraphic variations within these coastal aeolian deposits. Radar images were interpreted as showing dune cross-stratification (dip orientation and dip angle varied), scoured bounding surfaces, buried paleosols (where present), 24 2013 GSA Abstracts with Programs as well as the position of the water table. The internal dune structures revealed by GPR graphically demonstrate the response of aeolian dunes through time and to variations in wind regime, sediment supply, and human interference. Data will presented from selected study sites with in the US (California, Michigan, Oregon, North Carolina, Washington, Wisconsin) and other locations worldwide. Where possible, comparisons to available data and/or models will be made. 18-4 BTH 10 Larson, Mark [218721] ARCHAEOLOGICAL GEOPHYSICS AT THE NATHAN BOONE HOMESTEAD STATE HISTORIC SITE, SW MISSOURI MICKUS, Kevin L., Geosciences, Missouri State Univ, 901 S National Ave, Springfield, MO 65804-0087, LARSON, Mark, Geology, Missouri State University, Springfield, MO 65897, Mark3@live.missouristate.edu, and SOBEL, Elizabeth, Department of Sociology, Anthropology, and Criminology, Missouri State University, Springfield, MO 65897 The Nathan Boone Homestead was established by Nathan Boone, his family, and enslaved African Americans in Ash Grove, Missouri in the 1830s. Nathan Boone was the son of famed frontiersman Daniel Boone and was a significant figure in Euroamerican settlement of the trans-Mississippi west. Previous archaeological excavations and geophysical studies indicated a number of cultural features (both identified and anomalous) at the site. In this study, we synthesize the results of new and previous geophysical research at the site including GPR, resistivity, magnetic, and electromagnetic surveys. The results clarify the location and composition of cultural features including the Boone family cemetery, slave cemetery, pathways, domestic structures, and agricultural structures. These findings will aid management and research at the site by the Missouri Department of Natural Resources. 18-5 BTH 11 Kuhl, Alexandria [218744] COUPLED INVERSION OF ELECTRICAL RESISTIVITY AND HYDROLOGICAL MODELS TO QUANTIFY SOIL MOISTURE DYNAMICS BELOW A MICHIGAN ECOTONE KUHL, Alexandria, Department of Geological Sciences, Michigan State University, 206 Natural Sciences Building, East Lansing, MI 48824, kuhlalex@msu.edu and VAN DAM, Remke L., Department of Geological Sciences, Michigan State University, 206 Natural Science Building, East Lansing, MI 48824 Anticipating how changes in land use and climate will impact water budgets requires understanding the relationship between soil moisture and vegetation across space and time. Unfortunately, traditional geophysical methods for capturing field-scale processes of this nature, such as remote sensing and in situ point measurements, have their limitations. Electrical resistivity (ER) however, has been identified as a potentially powerful geophysical tool for studying root-zone moisture dynamics at sub watershed scales. Despite recent advances, interpretation of geophysical data often occurs independently from hydrological observations, causing uncertainty and propagating measurement errors. This research uses 1D ER soundings with a coupled hydrogeophysical inversion model to determine the impact of changing vegetation types on soil moisture. The goal is to develop a more universal method for improving predictions of hydrological properties at field-scales through the use of coupled inversion techniques. The Kellogg Biological Station near Battle Creek, MI, provides a unique setting for this study, with a shift from mature forest to young forest, shrub, and finally grass. Across this ecotone, graphite electrodes have been permanently installed at 1.5m intervals along a 166.5m transect, with additional electrodes for the 1D soundings. Six sounding locations, roughly corresponding to each vegetation type, allow for shallow ER measurements. Reciprocal ER measurements with a-spacings of .5, .75, 1.5, 3, 4.5, 6, 7.5, 10.5, and 13.5m were conducted at each sounding location in June, August, and October 2012. Deeper measurements with a-spacings of 18, 24, 36, and 54m were collected in August and October only. Early interpretations suggest that seasonal and vegetative differences impact soil moisture distribution and plant water use. The coupled inversion model integrates four components. A hydrological model takes in parameters such as temperature, precipitation, soil and vegetation type, and outputs water content, which a petrophysical model converts to obtain 1D resistivity profiles. A forward geophysical model uses those values to determine apparent resistivities for comparison to those measured in the field. The outcome is then used for optimizing the hydrological model parameters. 18-6 BTH 12 Ma, Yuteng [218346] SPATIAL VARIABILITY OF SOIL MOISTURE IN A DECIDUOUS FOREST: INTEGRATING TIME- LAPSE RESISTIVITY, TEMPERATURE, AND THROUGHFALL MEASUREMENTS MA, Yuteng, Geological Sciences, Michigan State University, 206 natural science building, East Lansing, MI 48824, mayuteng@msu.edu and VAN DAM, Remke, Department of Geological Sciences, Michigan State University, 206 Natural Science Building, East Lansing, MI 48824 In deciduous forests, soil moisture is an important driver of energy and carbon cycling, as well as ecosystem dynamics. The amount and distribution of soil moisture also influences soil microbial activity, nutrient fluxes, and groundwater recharge. Characterizing the interactions between vegetation and soil moisture is critical to forecast water resources and ecosystem health in a changing climate. However, these interactions are difficult to measure, both in time and space. Recent studies have shown the ability of electrical resistivity tomography to characterize the spatial and temporal dynamics of soil moisture dynamics below a range of different vegetation types. In this study, we investigated the spatial variability of the soil water budget of a deciduous forest in lower Mid-Michigan. For the duration of the 2012 growing season, bi-weekly measurements of canopy throughfall, soil temperature and soil moisture were collected along a 125 m long transect that extended from the forest into an adjacent grassland. The canopy throughfall data were collected using a series of 24 innovative funnels that integrated over four-week time periods. At the same locations (19 in the forest and 5 in the grassland), soil temperature was measured at 5 cm depth. Subsurface distribution of soil moisture was estimated by inversion of weekly electrical resistivity datasets. Additional equipment and data included two tipping bucket rain gauges, leaf area index measurements, vertical soil temperature profiles, and capacitance water content probes. Fluid salinity, temperature, and pressure (depth) were continuously monitored for the water table below the forest and grassland. Our results highlight the strong correlation of the shallow subsurface soil moisture distribution with rainfall intensity and vegetation cover. 18-7 BTH 13 Hart, J. [218661] GEOPHYSICAL ASSESSMENT OF LANDFILL CAP INTEGRITY AND LEACHATE LEAKAGE AT A MIXED WASTE LANDFILL HART, J., CIOPPA, M.T., and YANG, Jianwen, Earth and Environmental Sciences, University of Windsor, 401Sunset Avenue, Windsor, ON N9B 3P4, Canada, hartn@uwindsor.ca Concerns have been expressed about a closed, mixed-waste landfill in Southwestern Ontario regarding precipitation infiltration, because of a non-contiguous cap and potential leachate
leakage. This study aims to use two surface geophysical techniques (conductivity and resistivity profiling) to delineate the thickness of the landfill cap and locate any leachate plumes. The electrical imaging survey was conducted on 6 parallel E-W lines across the length of the landfill, using an ABEM Lund Imaging System. The surveys were made using a Wenner-α array with 2 meter electrode spacing. A conductivity survey, using a DualEM2S and DualEM4S, was conducted over the same lines, followed by a survey conducted on 15 N-S lines perpendicular to the original six lines. Several conductivity profiles were also made in a field just to the south of the landfill. ArcGIS geospatial analysis modeling software was used to produce conductivity maps for depths of 1, 2.2, 2.8 and 5.8 m (DualEM2S PRP, HCP and DualEM4S PRP and HCP, respectively). All showed similar patterns. The conductivity values varied considerably (2.2- 461mS/m). Several N-S linear anomalies were evident extending outside of the landfill towards the adjacent field. On the resistivity profiles, a number of low resistivity anomalies, near the surface, suggested that the landfill cap was not intact. Deeper low resistivity anomalies (> 5 meters) suggested the presence of leachate and was consistent with the known position of leachate within the landfill. The conductivity data correlated well with the resistivity surveys to delineate inconsistencies in the landfill cover and indicated the presence of leachate which may affect the field adjacent to the landfill. 18-8 BTH 14 Joshi, Siddharth Dilip [218499] GEO-ELECTRIC INVESTIGATION OF UNDERGROUND LEACHATE DISTRIBUTION AT A CLOSED LANDFILL IN SOUTHWESTERN ONTARIO, CANADA JOSHI, Siddharth Dilip1 , YANG, Jianwen1 , SERERES, Clayton2 , and TAMR, Radwan2 , (1) Earth and Environmental Sciences, University of Windsor, 401 Sunset Avenue - University of Windsor, Windsor, ON N9B 3P4, Canada, joshis@uwindsor.ca, (2) GENIVAR Inc, 4510 Rhodes Driver, Suite 720, Windsor, ON N8W 5K5, Canada Contamination due to landfill leachate can cause disastrous effects to aquifers used for groundwater supply. In this study, two geo-electric techniques were employed to investigate the underground leachate distribution and the subsurface geology at a closed site in southwestern Ontario, Canada. Conductivity mapping was first conducted over the study site using a frequencydomain EM terrain conductivity meter, which reveals an anomalous zone with the apparent conductivity values ranging between 130-500mS/m, concentrated in the 200m (S-N) by 80m (W-E) rectangle area at western half of the site. The DC resistivity survey was then carried out in the same area with 8 S-N profiles and 3 W-E profiles measuring 200m in length using a Wenner-α configuration. This arrangement of electrodes has an approximate exploration depth of 30m, which aids in outlining the waste and upper sand aquifer, the underlying silt/sand aquitard, and the lower sand aquifer. Our resistivity survey results exhibit an inconsistency in the clay cap thickness on almost all the profiles conducted. The results also indicate that the contamination plume is mainly travelling southwards at the base of the upper aquifer just below the waste, with a minor vertical component into the upper weathered portion of the silt/sand aquitard at some locations. No contamination plumes seem to exist in the lower sand aquifer. These findings are critical in assessing the current leachate conditions and in evaluating the existing compliance monitoring plan for potential implementation at the site or other sites in elsewhere. 18-9 BTH 15 Estifanos, Biniam Haileab [218655] GEOPHYSICAL PROSPECTING FOR CONCEALED KARST NEAR BELLEVUE, OH ESTIFANOS, Biniam Haileab and STIERMAN, Donald J., Department of Environmental Sciences, University of Toledo, 2801 West Bancroft Street MS604, Toledo, OH 43606, Biniam.Estifanos@rockets.utoledo.edu The Bellevue area, Ohio is characterized by sinkholes and dolines that allow surface water to rapidly drain into the carbonate aquifer. During episodes of excessive precipitation, part of the state Route 269 floods due to groundwater welling up. Ver Steeg and Yunck (1932) report water seeping in areas without visible sinkholes causing 3-4 foot high flood during the spring of 1930. We are using gravity and electrical resistivity methods to investigate concealed karst and underground conduits north of Bellevue. We occupied closely spaced (20 and 50 m) gravity stations along three east-west profiles, two adjacent to a topographic depression we interpret as a sinkhole complex. At this stage there is only a marginal suggestion of gravity lows that might indicate subsurface voids. Four dipole-dipole resistivity profiles totaling 2 km show only one obvious void, adjacent to a sinkhole. However, most resistivity measurements were made during the drought of summer 2012, making the distinction between voids and carbonate bedrock difficult. Repeat measurements will be conducted when the groundwater rises. A rise in groundwater level will convert air-filled voids (high resistivity) to water-filled voids (low resistivity). Electrical resistivity was used to detect air and water filled cavities at Seneca Caverns to the south, confirming this methodology. In January 2013, the static water level at USGS monitoring well at Bellevue rose 10 feet in response to 2 inches of precipitation. Stage level recorded at the Huron River east of the city shows a strong agreement with the static water level rise but dropped fast after the peak flow while the groundwater water level remained constant. The strong response of the groundwater to precipitation suggests that karstic porosity is quite low. Knowledge of the size and extent of the concealed karst will help in reducing impact of pollution on groundwater resources and delineating hazard prone areas. 18-10 BTH 16 Gerson, Laura M. [218426] USING GEOPHYSICAL METHODS TO STUDY KARST IN URBAN SPRINGFIELD, MISSOURI GERSON, Laura M., Geoscience, Missouri State University, Springfield, MO 65897, gerson9576@live.missouristate.edu, MICKUS, Kevin, Geology, Missouri State University, Springfield, MO 65897, and GOUZIE, Douglas, Department of Geology, Missouri State University, 901 S. National Ave, Springfield, MO 65897 Southwestern Missouri is located on the Springfield Plateau which mainly consists of Paleozoic carbonates and minor amounts of siliceous sediments. The dominant formation exposed in the area is the Mississippian Burlington-Keokuk Limestone which is nearly horizontal and susceptible to the formation of karst features such as sinkholes and caves. Near surface geophysical methods are useful in determining the location and nature of karst features, especially those that are not visible on the surface. Electrical resistivity, gravity, and very low frequency electromagnetics have been collected along a trend of mapped sinkholes where previous dye traces have indicated a large, long underground passage. Inverse modeling of the electrical resistivity profiles indicates pinnacles of highly resistive material with areas of low resistive material between them, indicating possible fractures in the bedrock. Some of the resistivity lows could be buried sinkholes. Depth of karst features varies from 5-12 meters and deeper. Two-dimensional gravity modeling shows a similar trend in subsurface topography. Both methods show a similar roughly linear trend that correlates with known sinkholes. Very low frequency electromagnetics does not correlate as well due to its susceptibility to noise, but one-third of the profiles do correlate with the electrical resistivity profiles. SESSION NO. 19 18-11 BTH 17 Yaqoob, Muthanna Yousif [218626] DETECTION OF BEDROCK FRACTURES AND JOINTS BENEATH COVER: GEOPHYSICAL APPROACHES TO AN ENGINEERING GEOLOGY PROBLEM YAQOOB, Muthanna Yousif and SAUCK, William A., Geosciences, Western Michigan Univ, Kalamazoo, MI 49008, muthanna.y.yaqoub@wmich.edu This research used geophysical methods to detect the presence of sub-vertical failure planes, their direction(s), and their frequency in bedrock beneath soil or glacial drift overburden. Azimuthal measurements using the seismic, electrical resistivity (ER), electromagnetic conductivity and ground penetrating radar (GPR) were made to evaluate which techniques might provide the best indication of the bedrock joints, faults, or shear zones. Measurements were made at multiple sites near each of three locations: Jackson, Alpena, and Grand Ledge, Michigan. The first two are former limestone quarries and the third is underlain by sandstone. Seismic measurements began with one or two linear refraction spreads, used to establish thickness of overburden and identify the S waves. The azimuthal seismic was done by placing the 24 geophones around a 10 or 15m radius circle (15 degree intervals), with the shot point in the center, measuring arrival times of the P and S waves. The EM-31 conductivity was used to quickly determine that there were no wires or pipes in or near the survey circle, as well as to profile along the diameters of the circle at 12 different azimuths. The square array was used for the resistivity measurements in the same circle, with the diagonal of the square being the circle diameter. This array was rotated to 12 unique azimuths at 15° intervals. GPR was tested at one site using 100 MHz antennae. The Rx was at the center, and the Tx was moved around the circumference of the circle at 15° intervals, to measure the arrival times of the ground wave. Reference measurements of the strikes of failure planes were made using a Brunton compass and photographs at adjacent bedrock exposures. Verification of results was done by comparing the geophysical results and the measured strikes and dips of the nearby exposures of the joint systems. The preliminary analyses of the results showed coincidence of the tests results with the strike measurements in some areas, whereas others did not. Some of the methods are very sensitive to variations in thickness of the overburden. These effects, as well as lateral resistivity gradients in the bedrock and overburden can apparently cause false indications of fracture systems. 18-12 BTH 18 Mogren, Saad [217949] REACTIVATION OF THE ABU-JIFAN FAULT BORDERING THE RAYN ANTICINES IN EASTERN SAUDI ARABIA: GRAVITY MODELING OF A SEISMOGENIC CRUST MOGREN, Saad and MUKHOPADHYAY, Manoj, Geology and Geophysics Department, King Saud University, PO Box 2455, Riaydh, 11451, Saudi Arabia, smogren@ksu.edu.sa The Abu-Jifan Fault truncates the Rayn anticlines along an 1100 km long margin within the Rayn Microplate in eastern Saudi Arabia. This set of anticlines is comprised of six sub-parallel super-giant anticlines, including the Ghawar uplift. Crust on either side of the fault is seismically active; width of the seismic zone varies from 170 – 220 km. The Ghawar anticline is however seismically intensely active which is supposed to be an outcome of fluid-extraction induced seismicity. Top part of this seismogenic crust is currently intensely deformed in consequence to induced seismicity below the Rayn anticlines and prevailing east-west stress. Here we argue that induced seismicity plays an important role in reactivating the Proterozoic east-west faults in the deeper crust. An integrated geophysical modeling approach is next adopted to derive the deeper geometry of the Abu-Jifan Fault that slices the seismogenic crust south of the Ghawar anticline. Geophysical data sets include: seismic velocity analysis for crust and top- lithosphere, IRIS seismic line interpretation for the Arabian Platform as well as the crustal structure and upper mantle stratigraphy from receiver function analysis and shear-wave splitting studies, conventional seismic interpretation for deep sedimentary layers, isopach map prepared for the major sediment lithologies, and the relevant density information for the major formations deduced from density logs obtained from drill holes in the oil fields. Their combined use is found to be a potentially powerful tool for investigating the deeper fault geometry which is modeled by gravity inversion along a profile in central part of the fault. Gravity modeling suggests that the Abu-Jifan Fault is a deep penetrative strike-slip fault, demarcating a denser crust along its north margin. SESSION NO. 19, 1:30 PM Thursday, 2 May 2013 T8. Addressing Environmental Aspects of Geology: Research, Pedagogy, and Public Policy (Posters) Schneider Hall, Courtyard 19-1 BTH 19 Musch, Steven C. [218735] INTERACTIONS BETWEEN DUNE TRAILS AND CIRSIUM PITCHERI HABITAT MUSCH, Steven C., HILVERDA, Elaine, LEGGE, Evan A., STRYDHORST, Natasha A., and VANDERBILT, Lucas E., Geology, Geography and Environmental Studies, Calvin College, 3201 Burton St SE, Grand Rapids, MI 49546, scm3@students.calvin.edu This study looked closely at the conditions of a threatened species habitat when it exists among unmanaged dune trails. A fourteen-acre plot of land on the eastern coast of Lake Michigan was recently purchased for conversion from private land into a dune preserve. This property includes hummocky foredunes, blowouts, and two stabilized parabolic dunes, and it serves as critical habitat for the threatened species Cirsium Pitcheri (Pitcher’s Thistle). To determine the condition of the habitat, a study was done to locate all specimens, gauge the age of the population, and explore the effects of anthropogenic disturbance. GPS mapping was used to create an inventory of all specimen locations and all observed trails through the property. Measurements were taken of each plant to gauge the age of the population and the GPS results were assembled in a map to observe the density. Our results showed 206 Cirsium Pitcheri specimens, most of which appeared to range from three to six years of age. Spatial analysis of the GPS data showed two distinct groupings of plants along with numerous unmanaged trails. The largest trail, which divided the two groups of plants, extended from the low point between two large parabolic dunes out to the beach. We observed that the heavy use of this trail combined with an extension of the stabilized portion of the dunes produced unfavorable conditions for Cirsium Pitcheri. With these results we were able to provide the new property owners with important information regarding critical habitat of Cirsium Pitcheri. 2013 GSA North-Central Section Meeting 25
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