Faculty and student presentations, Fall 2005

Geology faculty will be presenting papers and posters this fall at the annual GSA, SVP, and MetSoc meetings. Click on the names below to read abstracts...

Pranoti Asher, Kelly Vance, and Steve Jenkins - GSA Meeting, Salt Lake City, UT
Jason Dittmer - Popular Culture Association in the South Conference, Atlantic Beach, FL
Jason Dittmer - National Council on Geographic Education Conference, Birmingham, AL
Jason Dittmer - Southeastern Division of the Association of American Geographers Conference, West Palm Beach, FL
Jonathan Geisler - SVP Meeting, Mesa, AZ
Mike Kelley - Annual Meeting of the Meteoritical Society, Gatlinburg, TN
Jennifer Kopf - Southeastern Division of the Association of American Geographers Conference, West Palm Beach, FL
Jim Reichard- GSA Meeting, Salt Lake City, UT
Dallas Rhodes- GSA Meeting, Salt Lake City, UT
Dallas Rhodes - AGU Meeting, San Francisco, CA

The purchase of a Rigaku MiniFlex XRD (NSF DUE 0311730) allowed us to create project-based investigations of household and construction materials and soils to explore properties and application of industrial minerals in an environmental geology laboratory course at Georgia Southern University. Students collected and analyzed their own data, applied higher order skills and worked in small groups during the course.

The household materials exercise included the basic theory of XRD and the identification of the mineral content of various cleaning agents (e.g. bathroom and kitchen cleaners), cosmetics, personal hygiene products (e.g. toothpaste, deodorant), and over the counter medicine. The construction material exercise included identification and discussion of essential minerals components in building materials and the identification and hazard assessment of asbestiform minerals. The soils exercise, linked to a campus field trip, required determination of the minerals present in soil at different sites and horizons and relating mineral content to soil properties and environment of origin.

Considerable planning and preparation time were necessary prior to conducting these laboratory exercises. Managing the laboratory time to provide adequate "hands-on" time for each student group was critical for successful implementation of the exercises. One-half of the laboratory sections over the grant period were taught these exercises in the traditional manner while the rest used the XRD. Both groups were measured twice: a pre-test at the beginning of the semester and a post-test after completing the exercises. While the pretest scores did not differ significantly between the two groups, the post-test score for many of the XRD groups was slightly higher than many of the non-XRD groups. Results from our evaluation suggest that this method of instruction of mineral science concepts has improved student learning and the attitudes of students enrolled in our courses. The XRD has also been used in other courses, senior thesis research projects, teacher workshops, and community outreach efforts. Several presentations and dissemination efforts have resulted from this project.

GEISLER, Jonathan H., Dept. of Geology and Geography and Museum, Georgia Southern University, Statesboro, GA 30460

Although paleontological data is essential in estimating divergence times among taxa, current methods that assess the quality of these estimates focus on fossil abundance not phylogeny. Stratigraphic debt, as calculated in stratocladistics, can be used to assess estimates of divergence ages. This is accomplished by extending each node, one at a time, to the next oldest stratigraphic interval. The increase in stratigraphic debt, as compared to the total debt of the most parsimonious trees, is referred to as the potential stratigraphic debt (PSD). If a phylogeny and the fossil record are reasonably accurate, then the larger the PSD, the better the divergence estimate. Since each node is extended by the same amount, the PSD is a function of the number of separate ghost lineages that must be extended.

Molecular clock studies often choose a few paleontological-based divergence ages for calibration points, and then use an evolutionary model to estimate the ages of the remaining nodes on the tree. In many cases, molecular estimates imply that vast portions of the fossil record are missing, such as with the supposed Mesozoic radiation of placental mammals. Calculations of PSD's on recent mammalian phylogenies suggest that two branching points are particularly reliable: 1) a split between Cetacea and Hippopotamidae at 53.5 Ma and 2) the divergence between Rodentia and Lagomorpha at 62 Ma. Pushing either of these nodes back in time would entail stratigraphic debt over several lineages. If an age of 62 Ma for the rodent-lagomorph split is accepted by molecular-clock studies, much of the discrepancy between paleontological and molecular estimates for the divergence ages among placentals would disappear.

Asteroid 4953 1990MU was observed over the 0.8-2.5 microns spectral interval using the 52-channel double CVF system at the NASA Infrared Telescope Facility. Preliminary analysis of these data [1] reported a compositional heterogeneity over the surface of this asteroid. A careful reanalysis of the dataset has resulted in a better understanding of the spectral characteristics of 4953, and quantitative analysis of the near-infrared absorption band parameters has been performed following procedures described by [2]. This latest work supports the previous interpretation of body with at least two distinct mineralogical regions on its surface.

The near-infrared spectrum from 4 June 1994 exhibits a significant, well-defined absorption feature near 1.2-1.3 microns. There are three possible explanations for this feature: (1) it is due to the presence of a large feldspar component on the asteroid; (2) it is a side lobe of an olivine absorption feature; (3) it is due to the presence of a high-Fe pyroxene component. If this feature is feldspathic, it would rule out a chondritic nature for the asteroid.

Lightcurve segments were extracted from infrared data collected on two consecutive nights. Based on these segments, it was previously reported [1] that the most likely rotation period appeared to be 6.5 hours. Subsequent work by [3] used discreet filter data to obtain a lightcurve with a period of 14.218 hours. A smaller dataset for two nights by Erikson et al. (2000) includes only one lightcurve minimum and one maximum, but appears to be consistent with the lightcurve of Mottola et al.

References: [1] M. S. Kelley and M. J. Gaffey 1995, 26th Lunar and Planetary Science Conference, p. 731. [2] M. J. Gaffey et al. 2003, In Asteroids III, pp. 183-204. [3] S. Mottola et al. 1995, Icarus 117, 62-70. [4] A. Erikson et al. 2000. Icarus 147, 487-497.

Hybridity in colonial East Africa
Jennifer Kopf
Georgia Southern University

This paper examines hybridity in coastal East Africa during the German colonial era in three contexts: Zanzibar and East Africa prior to colonization, the German colonial view of hybridity, and an attempt to introduce hybridity into German schools via the endowment of a government school open to all students, offering Islamic instruction alongside other subjects. This discussion recovers "hybridity" from its fate as a theoretical trope, showing its usefulness in understanding colonization. The paper also suggests that people sought to continue past relations through the use of ante-colonial discourses. This discourse is askew of the colonial project, but is not called into being by colonization.

MAPPING GROUNDWATER SPRINGS WITHIN SCOUR POOLS IN COASTAL RIVERS IN GEORGIA
REICHARD, James S., Dept. of Geology and Geography, Georgia Southern University, P.O. Box 8149, Statesboro, GA 30460-8149, jreich@georgiasouthern.edu.

Concentrated spring discharge from the Floridan aquifer to rivers on the Florida peninsula is common, but largely unknown in coastal Georgia because upward flow is inhibited by thick confining units. However, shallow artesian aquifers above the Floridan may provide small, but locally important spring discharge to coastal rivers in Georgia. The purpose of this study is to test the hypothesis that artesian springs are present in coastal Georgia and play a subtle, but important role in the ecology of coastal rivers. This hypothesis is currently being tested at two deep pools known to provide critical summer habitat for Atlantic and shortnose sturgeon. At these locations general chemistry (Na, NH4, K, Ca, Mg, Cl, NO3, and SO4) and other parameters (temperature, pH, dissolved oxygen etc.) are measured from discrete samples being collected along the streambed and in vertical profiles.

Preliminary data show only subtle differences in most chemical species between upstream control sites and sites within the deep pools - differences in physical parameters are also small. However, calcium and alkalinity along the riverbed show strong concentration gradients that increase within the deep pools - pH also increases slightly. Based on these data, groundwater from aquifers containing calcite appears to be entering the deep pools and mixing with surface water in the rivers. Moreover, spatial distribution of the geochemical data indicates that groundwater discharge is taking place along a linear trend as opposed to a single spring head.

Both deep pools are steep-sided and elongate scour depressions whose bottoms are 3-5m below the average depth of the riverbed. The combined geochemical and bathymetry data suggests that the scouring process may have breached confining beds of shallow artesian aquifers, creating linear zones of groundwater discharge. Another possible model is that scouring exposed a fracture zone, thereby allowing artesian groundwater to discharge into the stream. More detailed sampling within the river will produce a refined conceptual model. Eventually, nested groundwater wells will be installed which should establish the chemistry of the groundwater responsible for the mixing patterns being observed in the rivers. Stratigraphic information will be obtained during well installation.

The Carrizo Plain is the only closed basin in California's southern Coast Ranges and records both climate and tectonic activity. The Plio-Pleistocene Paso Robles formation that underlies the basin indicates drainage from the Carrizo once reached Monterey Bay through the Salinas River. Alluvial fans spreading into the Carrizo from the Temblor Range are cut by the San Andreas Fault. Warping of the Plain associated with the fault and tens of meters relative uplift on the southwestern side of the basin may have severed the connection to the Salinas. Extensive clay dune remnants on the northeastern and eastern sides of the main basin and a deeply embayed southwestern shoreline are also consistent with southwest-directed tectonic tilting of the lake floor (about 1 m/km) during the Holocene. Luminescence and radiocarbon dates obtained during previous investigations of the lacustrine and clay dune deposits accumulated in the basin have indicated a maximum age of about 10 ka for the lake. These dates and the absence of identifiable strand lines led to the conclusion that drainage from the Carrizo remained open until approximately the end of the Younger Dryas. Two exploratory core sites were sampled in May 2005. The first site is on the dry lake flat of Soda Lake's northern basin. This site was chosen to test the thickness of the lacustrine sediment by reaching coarse-grained alluvial deposits. The sediment was cored and augured to a depth of ~14 m (the limit for the equipment) without penetrating the lacustrine clay. The second core was taken in the swale between the outermost clay dune and the next lower dune, both of which fringed the retreating lake. Approximately 6 m of essentially featureless clay-rich sediment were retrieved. The top of the outer dune ridge is ~8 m above the core site and the next dune is ~4 m higher than the swale, so 10-14 m of clay dune sediment accumulated here. Taken together, the material retrieved from the cores is interpreted as evidence that the "proto-Soda Lake" that occupied the Carrizo Plain was much larger than had been suspected previously, that external drainage was probably lost during the Pleistocene (which has implications for the rate of deformation), and (on the basis on an OSL date obtained from the top of the outermost dune) that the lake became saline enough for clay dunes to form before 16.7 ka ago.

Because of the small number of recent graduates, the Department of Geology and Geography at Georgia Southern University was placed on the list of programs to be monitored by the University System of Georgia's Board of Regents in August 1998. With only 23 majors at the time, the need to grow the program was obvious to everyone. Facing the reality that the survival of the Department was at stake, the faculty made enhancing enrollments its highest priority. After consulting a variety of published information and talking to faculty from the incredibly successful Department of Geology and Geography at Northwest Missouri State University, the faculty adopted a goal of having the combined number of geology and geography majors in the department equal 1% of the university's undergraduate enrollment, which then stood at 12,400.

The most important move toward the goal occurred when the Department began actively recruiting majors from all introductory geology and geography courses. Recruiting took a variety of forms that ranged from suggesting that students doing well in a course consider majoring in the field to formal presentations on geology and geography as careers. Since the Spring 2001 semester, recruiting talks have been given in every introductory level geography and geology class by a member of the faculty other than the course's instructor. The presentations emphasize how geology and geography promote the development of important marketable skills (e.g., critical thinking, problem solving, writing, public speaking, cultural awareness) and technical expertise (especially GIS) that are essential in obtaining employment and in career advancement. The presentations occur during the week preceding the Thanksgiving holidays, so students will have the opportunity to discuss this important choice with their parents. This schedule also gives students time to make their decision before registration for the spring semester. Soon after the recruitment efforts started the number of majors in the program began to increase and that upturn has continued through the present. In December 2004, the number of majors topped 100 (almost evenly split between geography and geology) for the first time in the history of the Department. By the end of the Spring 2005 semester, the department had reached its original goal of 124 majors.

Other activities during the period contributed to the Department's success. Adding a Bachelor of Arts degree in geography attracted students interested in cultural geography. Far ranging field trips (e.g., Hawaii, Ecuador) have added greatly to our majors' breadth of experience. Social events, including an annual awards dinner and gatherings for alumni, have helped the students to feel a part of the Department. Undergraduate research experiences increased in quality and students began to present their work at professional meetings at all levels. All of these activities have helped to give majors a stronger attachment to the Department and have made them better recruiters of other motivated students.

The survey given to graduating seniors asks about the importance of a number of activities in the student's decision to major in either geology or geography. No single event stands out as crucial. So although there is a clear temporal connection between the recruiting talks and increased enrollments, students do not consider it decisive in their choice. While recruitment efforts focused on career opportunities may not be the magic bullet to cure low enrollments, they certainly move students in our direction when the time comes to select a major.