ABSTRACT

Microfossils, and especially foraminifera, are a valuabletool for paleoenvironmental interpretations in coastalregions. Despite their utility, teaching of appliedmicropaleontology in undergraduate courses is limitedby the difficulty of identification of some taxa. Studentsin the University of North Carolina Charlotte's CoastalProcesses and Environments course were required todifferentiate downcore paleoenvironments fromback-barrier marshes near Charleston, South Carolina.Although lithology was useful for interpretingpaleoenvironments, sediments, combined with asimplified approach to microfossil identification, provedmost useful for determining depositional environments.Students used Civil War maps and global positioningsatellite technology to locate an 1860's tidal inlet.Gouge-auger cores and foraminiferal analysis were usedto stratigraphically confirm this strategically importantinlet.

The back-barrier marshes of Folly Island, SouthCarolina, is ideal for undergraduate foraminiferalresearch for two reasons: 1) Offshore outcrops ofOligo-Miocene strata provide foraminifera that act as anatural tracer for washover sediments and differentiatewashovers from flood-tidal delta deposits and 2)morphologically distinct agglutinated foraminifera, suchas M. fusca, simplify the identification of low- andhigh-marsh subenvironments.

INTRODUCTION

Foraminifera as a Teaching Tool - Foraminifera are anideal tool for measuring environmental change as theyare found in great abundance (often hundreds per cm3)in nearly all marginal-marine and marine environmentsand they are sensitive to alterations in their environment.Their short generation times, often less than a year,suggests the potential for a high degree of stratigraphicresolution (Martin, 2000).

Foraminifera have traditionally been used forbiostratigraphy and paleoenvironmental analysis(Applin et al., 1925; CLIMAP, 1984); however, theapplication of foraminifera for solving environmentaland geoarchaeological problems is of growing interest.Two previous geoarchaeological studies that usedforaminifera demonstrate their effectiveness inrecording environmental changes. Reinhardt et al. (1994)used benthic foraminifera to "enhance previousarchaeological interpretations" concerning the ancientharbor site of Caesarea Maritima, Israel. SerandreiBarbero et al. (2004) used salt marsh foraminifera similarto those found in the back-barrier marshes along theAtlantic coast to determine the position of lagoonalpaleoenvironments near Venice, Italy. Both studiesdemonstrate the effectiveness of foraminifera as a tool forrecreating paleoenvironments and corroboratingarchaeological data.

Re sources for in struc tors in ter ested in us ing foraminiferato teach paleoenvironmental anal y sis are abun dant (see,for ex am ple, www.ucmp.berke ley.edu/fosrec/Snyder&Huber.html, www.ucmp.berke ley.edu/fosrec/Olson1.html, and www.ucmp.berke ley.edu/fosrec/Olson3.html). De spite their util ity, the teach ing of ap pliedmicropaleontology in un der grad u ate courses is hin-dered by the dif fi culty of taxon iden ti fi ca tion.

The goal of this paper is to describe undergraduatestudents' use of foraminifera to 1) identify (and map) astrategically important Civil War landscape feature and2) corroborate historical descriptions of this terrain, thuslinking historical and modern maps. This paperdiscusses a simplified approach to foraminiferalidentification from Folly Island, South Carolina, andwhy this barrier island is an ideal field location forteaching applied micropaleontology.

The Local Setting - Students in UNC-Charlotte's CoastalProcesses and Environments course (upper-levelundergraduate) take a field trip each semester to FollyIsland, South Carolina. Folly Island is 16 kmsouth-southeast of Charleston, South Carolina, and athree hour drive from the UNC-Charlotte campus.Groins and seawalls make this barrier island one of themost heavily armored islands along the southeasternUnited States, yet the northern portion of the island, onceoccupied by a Coast Guard station, is relatively pristine.The combination of shoreline armoring and naturalenvironments on the same barrier island makes FollyIsland an ideal location for an undergraduategeomorphology or shoreline engineering field trip andresource materials and background information forinstructors are abundant (see for example, Harris et al.,1995, and Lennon et al., 1996).

Folly Island: The Historical Context - In an attempt totake Fort Wagner and Battery Gregg on Morris Islandand, in turn, Charleston, the Union army massed troopson the next barrier island to the south: Folly Island. As aresult, accurate maps from the early 1860's exist of theCivil War landscape (Figure 1).

In 1863 a small breach divided Folly Island into LittleFolly and Big Folly. The inlet was described by soldiersas "perfectly barren, and so low that the spring tidesfrequently swept entirely over it" (Hagy, 1993)producing a "spring" flood-tidal delta similar in origin toa low energy washover fan in the back-barrier marsh.The goal of the class project was to use global positioningsatellite (GPS) technology and Civil War maps to locatethis buried inlet and gouge-auger cores andforaminiferal analysis to identify it within the strata.

METHODOLOGY

Field Methodology - Students collected surface samplesfrom each of the following modern environments: beach,dune, tidal inlet, low marsh, and high marsh.Sedimentological and foraminiferal analyses were

526 Journal of Geoscience Education, v. 54, n. 4, September, 2006, p. 526-531

Using Foraminifera to Teach Paleoenvironmental Interpretationand Geoarchaeology: A Case Study from Folly Island, SouthCarolina

Scott P. Hippensteel Department of Geography and Earth Sciences, University of North Carolina atCharlotte, Charlotte, NC 23223, shippens@email.uncc.edu

Hippensteel - Using Foraminifera to Teach Paleoenvironmental Interpretation and Geoarchaeology 527

Figure 1. Little Folly Island in 1862-1863. This figure is a composite of several Civil War maps created byUnion cartographers, including the 1863 survey map produced by the U.S. Coastal Survey. On July 10, 1863,there were 32 rifled guns and 15 siege mortars on Little Folly Island.

Figure 2. Folly Island in August, 2005. Location of the vibra-cores and gauge auger transect is indicated, as isthe location of "the washout." Folly Island has retreated only a fraction of the distance of Morris Island, thebarrier island directly across Lighthouse Inlet.

conducted on these samples to aid in identification ofdowncore environments.

Students measured a transect SW - NE between twovibra-cores which had been taken in 1994 (Figure 2). Five30-mm gouge-auger cores were extracted to a maximumdepth of 6 m along this transect and samples were takenat 2-cm intervals in each core. Samples were dividedbetween the students, described in the field, andreturned to UNC-Charlotte for foraminiferal andsedimentological analysis.

Laboratory Methodology - Students sieved modern anddowncore samples using 1-mm, 0.5-mm, and 0.074-mmscreens. Their research reports included a bar-graph ofthe grain-size distribution of each sample. The 0.5-mmand 0.074-mm screenings were analyzed for microfossilcontent while the samples were still wet. Each studentwas required to pick and mount 40 foraminifera fromeach sample and photograph five representativeforaminifera from different genera. Foraminiferalanalysis was conducted using Meiji EMZ5TR binocularmicroscopes and digital photographs were taken using aNikon E4500 digital camera. Students then matched thedowncore assemblages to one of the following five(modern) biofacies:

1) Washover fans and storm deposits, containingmedium sand and shell fragments, were dominated byoffshore-indicative Globigerina spp. and calcareousOligo-Miocene foraminifera (Figure 3). TheseOligo-Miocene and offshore-indicative taxa included:Bolivina spp., Buccella spp., Bulimina spp., Buliminella spp.,Cancris spp., Cibicides spp., Eponides spp., Fursenkiona spp.,Hanzawaia spp., Nonionella spp., Quinqueloculina spp.,Rosalina spp., Saracenaria spp., Siphogenerina spp.,Stilostomella spp., Uvigerina spp., and Virgulina spp. Theseforaminifera are dredged from offshore during largestorms and deposited via the washover mechanismacross the back-barrier marshes (Hippensteel and Martin1999, 2000).

2) Flood-tidal delta/tidal inlet deposits varied betweenfine sand and mud and contained Elphidium spp.,Ammonia spp., and Globigerina spp., but lacked the

Oligo-Miocene foraminifera present in the washovers(Figure 3).

3) Beach and dune deposits contained well-sorted fineand medium sand and abraded Elphidium spp. andAmmonia spp. (Figure 4).

4) Low-marsh deposits were almost entirely mud andwere dominated by agglutinated foraminifera.Miliammina fusca was especially abundant, oftencomprising 50% of the assemblage (Figure 4). This facieshad the smallest mean grain size.

5) High-marsh deposits contained up to 25% fine sandand agglutinated foraminifera with a higher percentageof Trochammina inflata, Tiphotrocha comprimata, Jadamminamacrescens, Siphotrochammina lobata, and Ammotiumsalsum (Figure 4).

RESULTS

Stu dents com piled their foraminiferal andsedimentological data and con structed a cross sec tion be-tween the two vibra-cores. Core logs from the vibra-cores(orig i nally com piled by M. Scott Har ris, Coastal CarolinaUni ver sity) were pro vided to the stu dents. Theforaminiferal con tent of the mod ern fa cies was used tode ter mine downcore paleoenvironments and stra tig ra-phy along the transect and dis tin guish be tween bur iedmarsh, washover, and in let fa cies.

Figure 5 presents a detailed core log for core FBAC 04(Folly Beach Auger Core 04). This core log represents thecompiled findings from eleven students' samples. Theinterpreted environments in this core change fromwashover fan/low marsh from 5.0 m to 2.8 m to (CivilWar) flood tidal delta deposits from 2.8 to 1.9 m. The top

528 Journal of Geoscience Education, v. 54, n. 4, September, 2006, p. 526-531

Figure 3. Offshore indicative foraminifera present inthe washover fan facies, including Stilostomella sp.,Quinqueloculina sp., Rosalina sp. and Uvigerina sp.,and the flood-tidal delta facies, including numerousexamples of Elphidium spp., Ammonia spp. and theplanktonic Globigerina spp. Scale bar represents 100µm. Figure 4. Foraminifera present in the beach and dune

facies, including Rosalina sp. and Elphidium spp.Most foraminifera collected from these environmentswere either abraded or frosted. Agglutinatedforaminifera present in the low-marsh facies wereprimarily Miliammina sp. Agglutinated foraminiferapresent in the high-marsh facies, includingAmmotium salsum, Tiphotrocha comprimata, andTrochammina inflata. Scale bar represents 100 µm.

2-m of the core represent the modern high-marsh anddune environments.

Two cross sections are presented in this paper.Figure 6 portrays the lithology and stratigraphy of thetransect and Figure 7 presents the interpretation of thisstratigraphy.

CONCLUSIONS

Foraminifera Augmenting Historical Data - Studentsused the combination of historical military maps, GPS,and foraminiferal analysis to locate the 1863 inlet onFolly Island. Many local historians and coastal geologists placed this inlet approximately 1.5 km south of the actuallocation in an area referred to as "the washout" (Figure 2)."The washout" had been breached several times beforeand after the Civil War, including during HurricaneHugo in 1989; nevertheless, it is more probable that the"spring" tidal inlet described by Union soldiers waslocated significantly closer to the Confederate batterieson the southern end of Morris Island than previouslythought.

Folly Island, South Carolina: An Ideal Location forUndergraduate Paleoenvironmental Research - FollyIsland is ideal for undergraduate foraminiferal researchfor two reasons:

Offshore outcrops of Oligo-Miocene strata containforaminifera that act as a natural tracer for the source ofstorm sediments and differentiate hurricane depositsfrom flood-tidal delta facies and secondlymorphologically distinct agglutinated foraminifera, suchas M. fusca, simplify the differentiation of low- andhigh-marsh subenvironments.

Maps of Civil War landscapes provide further cluesabout the depositional environments present in therecent past. The environmental application ofmicrofossils to geoarchaeology is an area of growinginterest and undergraduate research may providefurther documentation and corroboration of historicalaccounts. Further, a multi-proxy approach whichcombines historical descriptions with sedimentologicaland foraminiferal analysis captures the interest ofstudents more than some typical paleoenvironmentalfield projects.

ACKNOWLEDGEMENTS

I would like to thank M. Scott Harris from CoastalCarolina University for the FBVC 12 and 13 vibra-corelogs and locations and the students enrolled inUNC-Charlotte's Coastal Processes and Environmentscourse for aid with extracting and analyzing the augercores used in this study.

Hippensteel - Using Foraminifera to Teach Paleoenvironmental Interpretation and Geoarchaeology 529

Figure 5. Core log for FBAC 04 (Folly Beach Auger Core 04). Offshore indicative Oligo-Miocene foraminiferawere most common in the washover sediments found in the bottom 2-m of the core while high-marshsediments dominate the upper 1-m of the core.

Figure 6. Lithology of the gouge-auger transect. Agglutinated foraminifera indicate a transgression in themarsh (high marsh flooded into low marsh) from approximately 2 m to 1 m.

Figure 7. Stratigraphy and interpretation of the gouge-auger transect. Storm generated washover fans werereplaced with the lower energy "spring" tidal inlet described by Union soldiers at approximately 3.5 m.Storm-generated and offshore-indicative Oligo-Miocene foraminifera are found solely in the sandy layersbelow 3.5 m.

REFERENCES

Applin, E. R., Ellisor, A. E., and Kniker, H. T., 1925,Subsurface stratigraphy of the coastal plain of Texasand Louisiana, American Association of PetroleumGeologists Bulletin, v. 9, p. 79-122.

CLIMAP Members, 1984, The last interglacial ocean,CLIMAP Members, Quaternary Research, v. 21, p.123-224.

Hagy, J. W., 1993, To Take Charleston: The Civil War onFolly Island (1st Edition), Charleston, WV, PictorialHistories Publishing Company, Inc., 92 p.

Harris, M. S., Gayes, P. T., and Krantz, D. E., 1995,Antecedent geologic controls on the modern barrierisland configuration and geomorphology in theCharleston, South Carolina coastal zone, in, LinkedEarth Systems, Congress Program and Abstracts, v.1, p. 65.

Hippensteel, S. P. and Martin, R. E., 1999, Foraminifera asan indicator of overwash deposits, barrier islandsediment supply, and barrier island evolution, FollyIsland, South Carolina, Palaeogeography,Palaeoclimatology, Palaeoecology, v. 149, p. 115 -125.

Hippensteel, S. P. and Martin, R. E., 2000, Foraminifera asindicators of storm deposition: Implications forbarrier island sediment supply and evolution. InMartin, R. E., editor, EnvironmentalMicropaleontology (1st Edition), Dordrecht, KluwerPress, p. 351 - 369.

Lennon, G, Neal, W. J., Bush, D. M, Pilkey, O. H., Stutz,M., and Bullock, J., 1996, Living with the SouthCarolina Coast, Durham, NC, Duke UniversityPress, 241 p.

Martin, R. E., 2000, Environmental Micropaleontology(1st Edition). Dordrecht, Kluwer Press, 481p.

Reinhardt, E. G., Patterson, R. T., and Schroeder-Adams,C. J., 1994, The Journal of Foraminiferal Research, v.24, p. 37 - 48.

Serandrei Barbero, R., Albani, A. D., and Bonardi, M.,2004, An cient and mod ern salt marshes in the La-goon of Ven ice, Palaeo ge ogra phy, Palaeocli ma tol-ogy, Palaeo ec ol ogy. v. 202, p. 229 - 244.

Hippensteel - Using Foraminifera to Teach Paleoenvironmental Interpretation and Geoarchaeology 531