Spring 2005 meeting abstracts
Geology and Geography

Jonathan Geisler

We report preliminary results of our study on the phylogeny of Delphinida, which includes the living cetacean families of Delphinidae, Phocoenidae, Mondontidae, Iniidae, Pontoporiidae, and Lipotidae as well as the wholly extinct families of Albireonidae, Kentriodontidae, and Odobenocetopsidae. To resolve delphinidan phylogeny, we gathered new morphological and molecular data and concatenated it with published data sets to create a matrix of 65 taxa (of which 40 are extinct) scored for 328 morphological characters, 25 transposon characters, and 945 informative nucleotide characters distributed across 7.4 kilobases. A parsimony analysis of this dataset found 78 most parsimonious trees each 6,796 steps in length. The strict consensus of the trees had 83% of the nodes resolved. As in several previous studies, we found a monophyletic Delphinoidea, a sister-group relationship between Monodontidae and Phocoenidae, and Inia and Pontoporia to be sister-groups. The extinct delphinidan Parapontoporia grouped with the Yangtze River dolphin, Lipotes, to form Lipotidae, which we found to be the most basal delphinidan clade. Perhaps the most surprising result concerned the paraphyletic family Kentriodontidae. The two species we sampled, Kentriodon pernix and Liolithax pappus, were excluded from Delphinida and instead were successive sister-taxa to the clade including Delphinida + Platanistoidea.
We optimized several morphological characters found in all or most extant species of river dolphins onto our most parsimonious trees. Previous authors had speculated that these characters were convergent and reflect adaptations to similar habitats, but our results suggest that most of these characters are symplesiomorphies. Given the disparate distribution of extant river dolphins, many have presumed that their ancestors were marine and the current distribution reflects three separate invasions of river systems. If only the distributions of extant taxa are mapped onto our trees; however, it is equally parsimonious to infer a freshwater ancestor for Inia, Pontoporia, Platanista, and Lipotes. When fossils from marine deposits are included in analysis, the hypothesis that each of the extant river dolphins evolved independently from different marine ancestors is favored.

The Woodlawn Topographic quadrangle lies within the Piedmont Physiographic province of the southern Appalachian Orogen near the Georgia-South Carolina border. The Carolina Terrane is one of the largest and most important lithotectonic components of the Appalachians with respect to historical production of base metals and precious metals. Detailed geology within many areas of the Carolina Terrane is poorly understood due to inadequate mapping, deep weathering and the lack of fresh and continuous exposures. Dominant rocks within the quadrangle are volcanic and epiclastic rocks that have undergone low pressure- temperature metamorphism (greenschist facies) typical of the Carolina Slate Belt. Geologic mapping documents the surface distribution of rock formations and structural features such as faults, veins, folds, foliation and mineralized areas. Previous geologic mapping within this portion of the Carolina Terrane identified the Persimmon Fork and Richtex Formations as the two major rock units; however, the nature of the contact between the formations is uncertain. Current mapping in the Woodlawn and Aonia Quadrangles suggests a new interpretation in which a facies relationship reflects proximal to distal changes in rock characteristics in the original depositional environment. Geochemical and petrographic analysis assist with correlation of rock units in the region and evaluation of chemical alteration. Trace element data allow for reliable rock classification and interpretation of the tectonic evolution. Field mapping integrated with geographic information systems (GIS) permits a new and detailed geologic map that may be easily updated as additional data are collected.

Susan Howell
Applied Coastal Research Laboratory
and
Department of Geology and Geography
Georgia Southern University

Clark Alexander
Skidaway Institute of Oceanography

Fort Pulaski is a Civil War era fort located on Cockspur Island, GA adjacent to the Savannah River shipping channel. To date, no quantitative evaluation has been made of the impact of port maintenance activities on natural and cultural resources within the Park. The objective of this study is to provide relevant information to Fort Pulaski staff so they may effectively comment on a proposal to deepen the shipping channel and devise a management plan.

In order to assess shoreline change rates over the period 1850-2000, we are developing an archive of visual imagery sources, including T-sheets, aerial photographs, surveys of channel depth, IKONOS imagery and side scan sonar surveys. Major features examined include the island shoreline and a large, dynamic oyster shell bar located along the Savannah River. These features were digitized to determine change rates for time periods that span major channel deepenings. The digitized shorelines were also used to determine endpoint shoreline change rates for the entire period of historic data. To analyze short-term dynamics of the oyster shell ridge, data collected includes progradation rate, length, height and width of the oyster ridge and distance from historic features. A series of benchmarks parallel to and adjacent to the oyster shell ridge allow measurement of onshore migration along its length. Information and results are being compiled outlining the rates of shoreline change and the dynamics of the oyster shell ridge over 10-100 year timescales, as well as changes associated with major harbor deepenings.

KELLEY, Michael S., Department of Geology and Geography, Georgia Southern University, P.O. Box 8149, Statesboro, GA 30460-8149, mkelley@georgiasouthern.edu
ASHER, Pranoti M., Department of Geology and Geography, Georgia Southern University, P.O. Box 8149, Statesboro, GA 30460-8149, pasher@georgiasouthern.edu
WELTEN, Kees C., Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450, kcwelten@uclink4.berkeley.edu
JULL, A. J. Timothy, NSF Arizona AMS facility, University of Arizona, Tucson, AZ 85721, jull@email.arizona.edu
SCHULTZ, Ludolf, Max Planck Institute fur Chemie, Postfach 3060, D-55020 Mainz, Germany, schultz@mpch-mainz.mpg.de
RODEN, Michael, Department of Geology, University of Georgia, Athens, GA 30602, mroden@gly.uga.edu
MERTZMAN, Stanley A., Department of Earth & Environment, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604-3003, stan.mertzman@fandm.edu
ALBIN, Ed F., Department of Space Sciences, Fernbank Science Center, 156 Heaton Park Dr., Atlanta, GA 30307, ed.albin@fernbank.edu

In August 2003, Statesboro, Georgia farmer Harold Cannon brought an unusual rock to the Department of Geology and Geography at Georgia Southern University. There are few naturally occurring rocks on the coastal plain of Georgia, so by definition, any rock found there is "unusual". However, this particular specimen turned out to be not only unusual, but otherworldly.

In mid-June, 2000 Cannon was harvesting a crop of butter beans when his mechanical bean picker pulled the rock up from his field. In the process, yellow paint from the device was deposited on the specimen. Cannon removed the rock and tossed it between a pair of produce freezers under a shed in his back yard. For more than 3 years the rock sat exposed to the elements. When Cannon was cleaning the area around the shed in summer 2003, he finally decided to find out exactly what the rock was. He said he suspected it might be a meteorite because it was heavier than expected for its size, and after breaking off a small fragment, he noticed it was very dark inside.

Our initial microscopic examination and thin section analysis at Georgia Southern University indicated that the 2.3-kg-specimen was most likely a shock-darkened ordinary chondrite, probably an L-type of petrographic grade 4-6 based on mineralogy, metal abundance, and alteration of the chondrules (Kelley et al. 2004). XRD analysis of the meteorite revealed olivine, orthopyroxene, and metal compositions indicative of an L-chondrite as well. Electron microprobe analysis of minerals in the Statesboro type specimen were performed at the Smithsonian Institution and revealed "very middle of the road compositions" for L-chondrites. The results showed an olivine composition of Fo75.4 and an orthopyroxene composition of En77.4 Fs20.8Wo1.8. Major, minor, and trace element data based on XRF analysis performed at Franklin and Marshall College also confirmed the high metal content of the sample. On the basis of these data we filed a report through the Meteoritical Society (Russell et al. 2004) to propose the name "Statesboro" for this meteorite in December 2003. We also answered questions from the media (e.g. Bragg 2003) and issued a press release through Georgia Southern University.

Electron microprobe analyses of minerals in a second chip of the Statesboro meteorite were performed at the University of Georgia and also yielded olivine (Fo74.6), orthopyroxene (En 77.1Fs21.2Wo1.7), metal, and suphide compositions well within the range for L5 chondrites. To date all of the feldspar probed in the second chip appears to have been converted to glass (maskelynite), which confirms the shocked nature of the specimen. Two phosphates, chlorapatite and merrillite, have also been identified in this sample.

The concentrations and isotopic composition of light noble gases were measured at the Max Planck Institute in Mainz, Germany, while a sample of ~130 mg was dissolved at the University of California, Berkeley, for analysis of cosmogenic radionuclides (10Be, 26Al, 36Cl and 41Ca). After chemically isolating these radionuclides from the dissolved sample, their concentrations were measured at the Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory.

As in many shocked L chondrites, Statesboro shows very low concentrations of radiogenic 4He and 40Ar, which indicate a major impact event on the L-chondrite parent body, less than 500 Myr ago. The measured concentrations of cosmogenic 3He, 21Ne, 38Ar yield a cosmic ray exposure (CRE) age of 5.1 +/- 0.4 Myr if we use the production rate formalism of Eugster (1988) and the measured 22Ne/21Ne ratio of 1.074. This age coincides with a cluster at ~5 Myr that is mainly observed for L5 and L6 chondrites with low radiogenic 40Ar (Marti and Graf, 1992).

The high concentrations of 36Cl and 41Ca (due to neutron-capture reactions) and low 10Be (~19 dpm/kg) indicate that the Statesboro meteorite had a larger pre-atmospheric size than most chondrites. We estimate that the Statesboro meteoroid had a radius of ~50-80 cm and weighed several tons. For such large objects the 22Ne/21Ne ratio is not a reliable indicator of shielding, leading to overestimation of the noble gas production rates. We therefore used the method of Graf et al. (1990), which is based on relatively constant 10Be/21Ne and 26Al/21Ne production rate ratios. This method yields a more reliable CRE age of 7.0-7.5 Myr.

The exterior of the meteorite exhibits a 2-3 mm thick orange-colored rind due to terrestrial weathering. Chemical analysis of this rind shows strong depletions (70-80%) in Mg and Ca relative to less mobile elements such as Al and Fe. These depletions are similar to those observed in extremely weathered meteorites from Roosevelt County, New Mexico (Bland et al. 1998), which show terrestrial ages >40,000 y. Measurements of cosmogenic 14C are in progress at the University of Arizona, Tucson, to determine the terrestrial age of the Statesboro meteorite.

The Statesboro meteorite is the twenty-third meteorite and the fourth L-chondrite to be found or seen to fall in Georgia. It is interesting to note that the other three Georgia L-chondrites are all L6's. The geographically nearest, previous meteorite to Statesboro was the Claxton, Georgia fall. That 1.4-kg-L6 chondrite smashed a mailbox on December 10, 1984. To date there is no scientific evidence to support previous speculation by Povenmire (2004) that the Claxton and Statesboro meteorites are connected. Not only are they different petrographic grades, but the Statesboro specimen is heavily shocked and darkened. In contrast the Claxton meteorite is relatively unshocked, and no other fragments were reported seen during, or found following that fall event. An immediate precursor connection between these two meteorites can be confidently ruled out.

This paper describes and explains the emergence of grassroots resource-management initiatives among First Nations in northern British Columbia. Aboriginal communities became particularly active in this facet of community activism in the 1990s by using provincial and federal initiatives to design and implement sawmills, ecotourist operations, comprehensive territorial-management programs, and initiatives for ecological research. These developments are especially unique in that they often involve members of the local non-Native community directly in the logistical and financial management of the operations. This presentation compares and contrasts the experiences of three aboriginal groups (Cheslatta, Lhk'acho, and Burns Lake bands), each of which has created joint-venture resource-management programs in their traditional lands. The paper explores the development of the initiatives, the cultural negotiations involved in the planning and implementation stages, and the socio-cultural effects of the programs on the Native and non-Native members of the local community. The paper then explains the emergence of similar initiatives across the province by interpreting the empirical evidence with concepts from recent theoretical work on local politics, social movements, and grassroots activism.

Michael H. Robinson
Applied Coastal Research Laboratory
Georgia Southern University

Clark R. Alexander
Skidaway Institute of Oceanography

Population pressure along the Georgia coast has greatly increased the number of docks that extend across the marsh, impacting marsh ecosystems. To understand the patterns and impacts of dock proliferation, aerial photography and field data were used within a GIS to quantify the number and area of docks affecting marsh. These maps show the footprint of docks from 1970 to 2000 on Wilmington Island, GA, and document a 90% increase in total dock area (24,048 m2 in 1970 to 45,679 m2 in 2000) and a 73% increase in number of docks during this period (174 docks in 1970 to 301 docks in 2000). Indicators of shading impacts to the Spartina alterniflora marsh (i.e., variation in stem density and plant height) were quantified along 56 transects. Average stem density was 56% lower beneath docks than adjacent to docks and paired data were statistically different. Plant height was not significantly different beneath or adjacent to docks. Although presently unquantified, shading effects may be important for the carbon budget of the marsh, which provides critical habitat for many commercially important species. Dock structures presently shade 0.5% of the marsh and maximum estimates of cumulative impact under current Georgia law suggest that ~5% of the marsh could be shaded. Additional information needs identified during this study include: an assessment of enhanced Spartina wrack accumulation around dock structures; a determination of the impact to benthic habitats by floating docks that sit on the bottom at low tide; and a comparative analysis of coastal county dock statistics with the baseline and trend data in this study.

The path towards sustainability: The case of Shanghai

Wei Tu

Shanghai, the biggest industrial and commercial coastal city in China, is remaking itself into a world city of business, finance, trade and navigation from a mainly industry based economy since 1990. The rapidly evolved urban environment is facing serious challenges under the process of fast economic growth, structure change and urban expansion. The ambitious urban development goals, the heavy history debts on urban infrastructure and environment investments are two major sources of environmental pressures. The pollution control and environment policy has evolved through three stages since the first one commenced at the early 1980s. The focus of the environment management approach has shifted from the setting of the management framework to pollution control to the latest sustainable considerations. While those management approaches proved to be effective in improving urban environment in the past two decades, they also pose a particular challenge on the sustainable development of Shanghai. The paper offers a new management paradigm based on Haughton's model on urban sustainable development and argues it will help the city toward the transition to sustainability.

VANCE, R. Kelly, HOWELL, Susan and JONES, Martin, Department of Geology and Geography, Georgia Southern University, Box 8149, Statesboro, GA 30460-8149, rkvance@georgiasouthern.edu

Geologic mapping was conducted at a 1:24000 scale along the northwest side of the inundated Little River valley of Georgia in the Woodlawn and Aonia quadrangles, between the Modoc zone and the Charlotte belt. Resulting geologic maps were converted into digital images for use in ArcGIS. The GIS data base includes sample points, structural, petrographic and geochemical data. The map covers Neoproterozoic to Cambrian greenschist facies rocks of the Carolina slate belt previously assigned to the volcanic dominated Persimmon Fork Formation and mudstone dominated Richtex Formation. The dominant regional rock fabric is a foliation striking N 55-70 o E, dipping 30-70 o NW. Small folds in the southeast portion of the Aonia Quadrangle display a N 50 o E axial trend plunging NE at 15 o. Intermediate to felsic subaqueous tuffs and coarse volcaniclastic rocks are interlayered with increasing proportions of greenstones, greywacke and mudstones toward the southeast. Thin beds of uniform, fine-grained siliceous rocks between the pyroclastic flows and sedimentary rocks may be the submarine equivalent of surge or airfall deposits. Graywacke beds grading upward to fine sands and laminated mudstones with local convoluted bedding, probably originated as submarine fans. Graded bedding and cross-bedding indicate northeast and northwest tops, respectively, as relict bedding changes from a dominant N 70-85 o W strike dipping 55-65 o NE in the Aonia Quad to a dominant N 70-85 o E strike with 50-74 o dips to the NW in the central Woodlawn Quad suggesting a N-NE trending regional syncline. The entire succession is interpreted as interfingering between inner distal, mudstone-dominated deep water facies and a proximal facies dominated by pyroclastic rocks and coarse volcaniclastic deposits. Greenstones interlayered with the tuffs and mudstones represent mafic lava, volcaniclastic rocks, dikes and sills. The presence of mafic rocks and local sulfide mineralization in this transition zone favors an intra-arc basin produced by arc extension.