What Rocks Reveal
Happenstance describes how a hike in the Chicopee Woods Nature Preserve turned into an ‘ah ha’ moment for Dr. Katayoun Mobasher. What she found will ultimately lead to discovery and insight that will shape perceptions of the geologic history of the region.
Rewind to Elachee Natural Resource Manager Lee Irminger’s introduction to Dr. Mobasher during his days as an undergraduate in the University of North Georgia’s (UNG) Institute for Environmental and Spatial Analysis (IESA) program. Several years ago, he invited this UNG geology professor to participate as a guest lecturer in Elachee’s Georgia Master Naturalist program series. This semester-long program series delves into local habitats and ecosystems with lecture and outdoor field experiences to better understand the local environment. Dr. Mobasher now participates annually in this program where she teaches adult learners about the geology of Georgia and conducts a guided geology-centric hike in the Chicopee Woods Nature Preserve.
In preparation for her first Georgia Master Naturalist lecture and field study, Dr. Mobasher explored the Preserve and found the geology of Chicopee Woods intriguing. Although the rich and complex geology of the Preserve is mostly covered with vegetation, there are several highly weathered exposed outcrops within its boundaries which provide a peek into its geology. With additional research she discovered the geology of the Preserve itself and its immediate vicinity had not previously been documented or described in detail. Knowing that fieldwork is the basis for all geological investigations, she wanted to further pursue this.
And So It Began...
Dr. Mobasher collected samples at outcrops to analyze them for elemental composition, mineral content and texture. She then recruited her colleague, Dr. Jerry Allison, Professor of Chemistry in UNG’s Department of Chemistry and Biochemistry to assist on the project, adding geochemical analysis expertise.
They applied for the UNG Presidential Summer Incentive Award, with Elachee Nature Science Center’s endorsement of their efforts, and were awarded $10,000 in funding for their research project, the Geochemical and Petrological Study of Rock Outcrops at the Elachee Nature Science Center. These UNG professors, along with two research assistants, Matt Palmer and Ana Ferreira, have been working since May 2019 to better understand the underlying minerals and rock formation of the Preserve. READ MORE and/or SEE UNG VIDEO
The research goal is to provide the first detailed investigation of the Chicopee Woods Nature Preserve’s geology, in collaboration with Elachee Nature Science Center, through geochemical and petrographic analyses of rock outcrops. Understanding the nature of the rocks in the Chicopee Woods will add to the understanding of the geologic history of this region.
UNG student researchers will apply analysis techniques to rock samples that are heavily weathered and, unlike the ideal samples depicted in textbooks, are challenging to understand and interpret. The work will include using satellite imagery and GIS to identify and map rock outcrops within the 1440-acre Nature Preserve.
At the start of her investigation, Dr. Mobasher realized that most of Hall County’s geology has not been studied in detail. The Preserve is geographically classified as lying along the northern portion of the Southern Piedmont at its boundary with the Blue Ridge Mountains, which includes the nearby Brevard fault zone. Previous investigations in Hall County have focused either on economic mineral deposits (quarries) or on identifying the general trend of the Brevard fault zone across the area.
The official Geologic Map of Georgia (Lawton et al., 1976) shows that surface geologic units of the Preserve belong to a lithology group identified as mica schist/ quartzite/ gneiss/ amphibolite. However, the map shows no spatial differentiation of these rock types within the boundaries of the Preserve.
No previous studies have provided elemental analysis of geologic samples from the Preserve, nor have samples been subjected to thin-sectioning (0.03-mm-thick specimens of minerals or rocks mounted on glass slides) and petrographic analysis.
The UNG researchers expect to present their findings at upcoming regional and national geological conferences of the Geological Society of America (GSA) and American Geophysical Union (AGU), with the undergraduate student researchers also presenting at a regional or national conference. Elachee will take their findings one step further. The information that is gathered and maps that are made will be organized into a ‘geology trail’ exhibit that will interpret the geology of the area for Elachee’s visitors.
The student researchers began data collection in late spring, continuing their efforts through the summer to collect and analyze thin sections of collected samples under a polarizing light petrographic microscope. This analysis will allow mineral content of rocks to be determined by their optical properties, even those minerals that are not discernible or identifiable in hand samples.
Researchers will also subject samples to elemental analysis in UNG’s chemistry lab as well as in the field. This analysis includes x-ray fluorescence (XRF) techniques and by dissolving samples and analyzing the results using an inductively-coupled plasma with mass spectrometer. To aid in field study, one of the XRF devices is hand-held and used in the field to determine elemental composition.
These optical investigative methods will allow the rock samples to be classified based upon the percent composition of certain elements. Subsequently, these processes will shed light on the make up of the rocks which will help better understand their history. Upon identifying the mineralogical content, researchers can then distinguish the different types of metamorphic, sedimentary and igneous rocks.
The historical perspective comes into focus if rocks are to be used to interpret geological processes and environments, as the optical mineralogy is an essential methodology necessary to reveal important information. Depending on what elements the rocks contain and on whether individual minerals from these rocks can be isolated for analysis (e.g., garnets from garnet schist), it may be possible to obtain a radiometric age for the formation of the mineral. Such information can help to establish the date of regional metamorphic events and contribute to the understanding of the geologic history of the region.
Larger Implications of this Study
In 2017 Dr. Mobasher developed a virtual Field Guide and Story Map within an online ArcGIS platform. It provides an expanded geological field guide which enhances the virtual experience, allowing users to present a GPS-located story point narrative, featuring images of geologic features including video and GigaPan photography. An ArcGIS app allows users to access this database on the go from their smartphone or tablet.
As a part of the current UNG research study, Dr. Mobasher intends to add a new chapter showcasing the geology of the Preserve to the Story Map. Each chapter includes a geodatabase that contains data fields designed to store information such as rock types, age, sedimentary structures, fossil content, size of the outcrop, and geologic structures and also is supplemented with additional learning and research tools such as geologic sketches, petrographic thin sections, video files and a geochemical database. The use of GigaPan photos facilitates visualizing geologic features at different scales in high resolutions. These images provide an online experience analogous to observing outcrops up close. Thus, these images that are being used for the geology of Georgia’s virtual Field Guide and Story Map are also suitable for use in classroom settings, for the community and for research purposes.
Dr. Mobasher has a Ph.D. in Structural Geology, GIS professional certificate, M.S. in Petrology, B.S. in Geology. Dr. Allison has a Ph.D. in Earth and Atmospheric Science, and M.S. in Geophysics, and a B.S. in Geology.
The Chicopee Woods Nature Preserve and Elachee Nature Science Center
Elachee Nature Science Center is nestled in one of Georgia’s largest protected greenspaces, the 1,440-acre Chicopee Woods Nature Preserve. A private, independently operated 501(c)(3) not-for-profit organization, Elachee promotes environmental understanding through education and conservation.
Elachee utilizes the Chicopee Woods as an outdoor classroom and is responsible for land management of this north Georgia forest as its Trustee in perpetuity, under the authority of the Chicopee Woods Area Park Commission. Here Elachee collaborates with community partners and volunteer corps to build, maintain and ensure a sustainable legacy. This conservation stewardship work restores and protects the health of its forest, streams and habitats, in addition to responsibility for ongoing maintenance of the Nature Preserve’s extensive 8-mile hiking trail system.
Gainesville Times related article published Sunday, August 25, 2019