Monthly AGS Meeting
“U.S. Energy Sources: Where it has Changed in the Last Decade”
presented by Ron Wallace, President of the Georgia Chapter of the American Association of Professional Geologists (AIPG)
Tuesday May 25, 2021 6:45 PM Eastern Standard Daylight Savings Time
Business Meeting: 6:45 PM – 7:00 PM
Presentation: 7:00 PM
Join from the meeting link: https://gsumeetings.webex.com/gsumeetings/j.php?MTID=m2de9a0f59d882cbeea9229311d11bca5
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Access code: 120 591 9826
In 2009, Ron Wallace, was on an energy committee and the results were published and presented at conferences and at the Atlanta Geological Society. The presentation was a review of our sources of energy in the U.S. and where they are being used. His talk also looked at the world energy production and predicted energy use to 2035. There was a discussion on environmental issues resulting from all energy sources. Most of the information came from the U.S. Energy Information Administration.
This presentation will compare the change in energy sources from the original presentation to more recent data, prior to the downturn caused by the pandemic. There will also be discussion on where the original 2035 predictions were correct and where they missed. The current data will be used to predict changes in energy sources to 2050. There will be a short look at the world energy sources and predict how it will also change by 2050.
Biography of Ron Wallace:
Ron Wallace has a BS degree in Oceanographic Technology from Lamar University and a MS in Geology from University of Kansas. He was employed by Exxon in South Texas and East Texas Production, Offshore Alaska Exploration, and Marketing in Environmental Department. He worked in the Atlanta area for a number of environmental consulting firms, then worked for the Georgia Environmental Protection Division and retired as a Program Manager in the Underground Storage Tank Program. He is President of the Georgia Chapter of the American Association of Professional Geologists (AIPG).
“Oil and Gas in the Gulf of Mexico Basin, with Tales from the Oil Patch”
presented by David Lynch, Geophysicist with Shell Oil, Louisiana (retired).
Tuesday April 27, 2021 6:45 PM Eastern Standard Daylight Savings Time
Business Meeting: 6:45 PM – 7:00 PM
Presentation: 7:00 PM
Join from the meeting link: https://gsumeetings.webex.com/gsumeetings/j.php?MTID=m2de9a0f59d882cbeea9229311d11bca5
or Join by phone 415-655-0002
Access code: 120 591 9826
Abstract: The Gulf of Mexico Basin has been a prolific region for finding and producing oil and gas. A widespread, thick layer of salt was deposited during the early opening of the Gulf in mid-Jurassic time; then huge amounts of sediment eroded from the Rockies to the Appalachians were piled onto that unstable salt base, producing a cornucopia of structural opportunities to trap oil and gas, with much variation from region to region.
The first part of this presentation briefly reviews some of the basics of petroleum geology, oil well drilling, logs, and business environment, to set up a common understanding for the second part which discusses the geology of different subareas of the basin. Specific areas include the Texas onshore/shelf growth faults, the Louisiana onshore/shelf/deepwater salt dome region, an ultradeep fold belt near Mexico, and aeolian sands generally south of Alabama. The presentation will also include discussion of the root causes of some industry-related disasters, and other more benign tales of interest.
Biography of David Lynch:
David Lynch was born and raised in the Atlanta area, and received his B.S. in Physics at the University of Georgia in 1976. He entered the graduate program at New Mexico State University in Las Cruces, where curious about the Rio Grande Rift that surrounded him, he discovered his love of geology and turned to a geophysics course of study. He received his Ph.D. in 1983 with a dissertation on computer models of continental rifting. He then joined Shell in Houston as an exploration geophysicist and held a series of international assignments involving acquisition, processing, and interpretation of seismic data, along with the drilling of numerous exploration wells. After a stint in Shell’s Research Center, he transferred in 1991 to the New Orleans office where he spent the first couple of years as a seismic interpreter seeking prospects on the Texas Shelf for Shell to bid on in federal lease sales. This was followed by a few years in borehole geophysics, solving special problems delineating flanks of salt domes. In 1997 he joined the deepwater producing assets division where he spent the rest of his career seeking locations to drill new wells in existing fields, and guiding these wells through drilling to final depth. This period also included being on occasional regional study teams to solve a special geo-related problems. He retired in 2014 and now spends most of his time on a country property in the woods northwest of Lake Pontchartrain, observing nature, and pursuing several geological interests.
Tuesday March 30, 2021 6:45 PM Eastern Standard Daylight Savings Time
Business Meeting: 6:45 PM – 7:00 PM
Presentation: 7:00 PM
“Geophysical Log Database and Digital Surfaces for the Floridan Aquifer System in Florida and Parts of Georgia, Alabama, and South Carolina” presented by Lester J. Williams, Hydrologist.
A database of borehole geophysical logs and other types of data files were compiled as part of studies of water availability and assessment of brackish- and saline-water resources (Williams and others, 2016). The database contains 4,883 logs from 1,248 wells in Florida, Georgia, Alabama, South Carolina, and from a limited number of offshore wells of the eastern Gulf of Mexico and the Atlantic Ocean. The logs can be accessed through a download directory organized by state and county for onshore wells and in a single directory for the offshore wells.
The objective of this study was to improve the overall understanding of the available fresh, brackish, and saline water resources for ongoing and potential future development. Specific tasks were to (1) develop a digital georeferenced database of borehole geophysical data to enable analysis and characterization of fresh, brackish, and saline aquifers (see locations in Fig. 1), (2) identify and map the regional extent of the fresh to saline aquifer systems and describe the thickness and character of hydrologic units that compose these systems, and (3) delineate salinity variations at key well sites and along section lines to provide a regional depiction of the freshwater-saltwater interfaces. Electrical resistivity and induction logs, coupled with a variety of different porosity logs (sonic, density, and neutron), were the primary types of borehole geophysical logs used to estimate the water quality in brackish and saline formations. The results from the geophysical log calculations were compared to available water-quality data obtained from water wells and from drill-stem water samples collected in test wells.
Gamma ray and resistivity markers were used to map the base of the aquifer system throughout much of the peninsular area with an example of these markers from a well in De Soto County Florida (Fig. 2). Mapped units include a low-resistivity zone near the base of the aquifer system often denoted by a basal gamma ray marker, a massive dolostone unit within the Oldsmar Formation, and the Glauconite marker unit. Although geophysical log response varies considerably throughout the area, individual high and low-permeability zones within the aquifer system could be mapped generally along distinct lithologic units such as shown for a well in Citrus County, Florida (Fig. 3). In this well the aquifer contains permeable zones near the top of the carbonate rock sequence, in the middle of the sequence (Avon Park Formation) and near the base of the system (Oldsmar Formation).
Using point data compiled from geophysical logs and water samples from wells, digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system were developed to define an updated hydrogeologic framework (Williams and Dixon, 2015). The dataset contains structural surfaces depicting the top and base of the aquifer system, its major and minor hydrogeologic units and zones, geophysical marker horizons, and the altitude of the 10,000-milligram-per-liter total dissolved solids boundary that defines the approximate fresh and saline parts of the aquifer system. The thicknesses of selected major and minor units or zones were determined by interpolating points of known thickness or from raster surface subtraction of the structural surfaces. Additional data contained include clipping polygons; regional polygon features that represent geologic or hydrogeologic aspects of the aquifers and the minor units or zones; data points used in the interpolation; and polygon and line features that represent faults, boundaries, and other features in the aquifer system.
Williams, L.J., Raines, J.E., and Lanning, A.E., 2016, Geophysical log database for the Floridan aquifer system and southeastern Coastal Plain aquifer system in Florida and parts of Georgia, Alabama, and South Carolina (ver. 1.1, December 2016): U.S. Geological Survey Data Series 760, 12 p., available at http://pubs.usgs.gov/ds/760/.
Williams, L.J., and Dixon, J.F., 2015, Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system in Florida and parts of Georgia, Alabama, and South Carolina: U.S. Geological Survey Data Series 926, 24 p., https://dx.doi.org/10.3133/ds926.
¬Williams, L.J., and Kuniansky, E.L., 2016, Revised hydrogeologic framework of the Floridan aquifer system in Florida and parts of Georgia, Alabama, and South Carolina (ver. 1.1, March 2016): U.S. Geological Survey Professional Paper 1807, 140 p., 23 pls., http://dx.doi.org/10.3133/pp1807.
Biography of Lester J. Williams Lesterw53679@gmail.com :
B.S. 1986 and MS 1990 University of Louisiana at Lafayette.
Independent consulting hydrologist with a passion for developing sustainable groundwater resources for agricultural, industrial, and commercial supplies. Worked as a practicing hydrogeologist in the engineering/consulting field from 1990 to 2000 working on industrial and military sites investigating extents of contamination and developing corrective actions in North Carolina, South Carolina and Georgia. Starting from about May 2000 and extending to 2015, worked tirelessly at U.S. Geological Survey conducting various groundwater studies in the Piedmont and Coastal Plain of Georgia including a major revision of the Floridan Aquifer System which is the main source of water in Florida and in parts of Georgia, South Carolina, and Alabama. Insights gained through these studies have greatly increased the understanding of regional stresses on groundwater availability and interaction with underlying and overlying water-bearing units.
Tuesday February 23, 2021 6:45 PM Eastern Standard Time
“Structural and Stratigraphic Controls on Saltwater Intrusion, St. Catherines Island, Georgia” presented by Robert Kelly Vance (Georgia Southern University)
Authors: Robert Kelly Vance, Jim Reichard and Jacque Kelly (Georgia Southern University) and Brian Meyer (Georgia State University)
With support from Georgia Sea Grant and the St. Catherines Island Foundation.
Abstract: St. Catherines Island (SCI), Georgia consists of a Pleistocene Silver Bluff shoreline sedimentary core flanked by Holocene ridge and swale, and salt marsh deposits. Holocene dunes cover the higher (4.3 – 7.9 m elevation) northern and eastern core, thinning to the west. A NE-SW trending lowland (2.5 – 5.0 m elevation) occupies the central and western portions of SCI and contains Holocene freshwater wetland deposits. Coring and radiocarbon dating in the lowlands revealed substantial variation in thickness (<1 m to > 3 m) of Holocene sediments, and variation in elevation (0.6 m to 4.3 m) of the Holocene/Pleistocene contact. Plant clasts from cores provided conventional ages of > 37,410 BP for Pleistocene strata. A wood clast in a core from the southern lowlands gave the oldest Holocene conventional radiocarbon age of 8,410 +/- 30 BP. Some relief on the Pleistocene erosional surface may be due to fault displacement as suggested by offsets in specific clay beds and distinct NE-SW and NW-SE linear geomorphic features. The former artesian springs and the active saltwater intrusion (by upconing) in the Upper Floridan of SCI require faults. The shallow aquifer systems are also experiencing localized pulses of saltwater intrusion. Coring and monitoring well installation reveal a water table aquifer (< 11 m depth) in Holocene and Pleistocene sands, and a semi-confined aquifer (>12.2 m depth) in Pleistocene sands, separated by an aquitard of Pleistocene clay and clayey sand. Head, specific conductivity and chemical data from 24 monitoring wells indicate very high tides and storm surges drive saltwater along permeable pathways to specific wells in the SCI interior. Certain wells in the semi-confined aquifer also react to tidal events, but have a lower background salinity than the unconfined wells. Geophysical profiles (GPR, ER) indicate permeable pathways are associated with faults and sag structures. Periodic influx of saltwater into the shallow aquifers of SCI should increase in frequency and extent with rising sea level and increased storm surge activity. The most recent well logger downloads reveal major storm surge and king tide salinity spikes in 2020, supporting this conclusion.
Biography of Robert Kelly Vance:
Ph.D. – 1989 New Mexico Institute of Mining and Technology
M.S. – 1984 University of Kentucky
B.S. – 1978 University of Kentucky
Kelly Vance grew up on a family farm in Kentucky and decided to major in geology after taking an introductory geology course at Elizabethtown Community College. He transferred to the main U.K. campus in Lexington where he completed his B.S. and M.S. degrees. He worked in DOE-funded Devonian oil shale field and geochemical research with the UK Geology Dept., the Kentucky Geological Survey, and the Institute for Mining and Minerals Research as a graduate student. Kelly did his Ph.D. work at New Mexico Tech and took a two year temporary position at Appalachian State University as he finished writing his dissertation. He has been teaching at Georgia Southern since the fall of 1989. The regular courses He teaches at GSU include Mineralogy, Petrology and Petrography, and Economic Geology as well as the field-based Sea Turtle Natural History and Barrier Island Environmental Geology courses on St. Catherines Island (SCI), Georgia. Research interests and activities include tectonic and geologic environment of Volcanogenic Massive Sulfide deposits, igneous petrology, applications of Ground Penetrating Radar, and barrier island hydrogeology. He also supports sea turtle conservation by monitoring SCI beaches for the GA DNR in the summer and teaching students while serving as co-director of the GSU Sea Turtle Program at St. Catherines Island.
Tuesday January 26, 2021 6:45 PM
“Ice Station T-3: Its Exciting History and its Importance for Science and U.S. Defense” presented by John Berry, FGS, PG(TX), CPG
Abstract: Ice Island T-3, a large (63 sq.miles) tabular iceberg, was manned by the U.S.Air Force and Navy for four different periods of time between 1952 and 1978. It was visited by USS Skate in 1958, and by the icebreaker Northwind in 1962. This latter visit led to some tragedy. The Iceberg circled the Canada Basin of the Arctic Ocean twice, even though it ran aground for several years on the northern shelf of Alaska. It drifted through the Fram Strait in 1983, and melted in the North Atlantic.
Over the years a tremendous variety of Geological and Geophysical research projects were carried out from the Island, besides routine charting of the ocean floor and mapping of the gravity and magnetic fields. These projects included studies of the aurora, measurement of the earth’s heat flow, detection of Russian nuclear blasts, studies of ocean-, sound-, and seismic-wave propagation beneath the ice, and sampling and dating of the ocean bottom sediments.
Biography: John Berry, FGS, PG(TX), CPG is a semi-retired geologist who worked on T-3 in the summer between college and graduate school. He began his professional career in Zambia exploring for copper, cobalt, limestone, and water. After moving back to the U.S., he taught at a Technical College in western North Carolina until joining Earth Satellite Corporation in Maryland to work on mineral and oil exploration projects worldwide. He joined Shell in 1982 to explore for gold, and then spent 15 years in exploration research and frontier oil exploration: he pioneered the use of natural oil slicks as an oil exploration tool in off-shore basins.
Tuesday Nov 24, 2020 6:45 PM
“Black Granite from Hell” presented by Steven Stokowski.
Abstract: In the center of the Rhode Island Veterans Cemetery is a large Ceremonial and Commemorative area. This dramatic, horseshoe-shaped memorial has sweeping cast-in-place concrete walls with fifty-eight, inlaid, 6-foot high, black granite panels having engraved veterans’ names. During the initial 1998-99 construction phase, the project was relatively trouble-free except that the availability of the large stone panels delayed the project for 7 months. The original granite specified was from Zimbabwe, but the architect actually wanted stone from South Africa, which was not available because of sanctions. Of the “black granites” available, the architect then approved a very dark and coarse-grained “granite” from Canada. Soon after installation, most of the stone panels progressively developed popouts and cracks. The only realistic solution to the pervasive failure was to replace all the panels, although the manufacturer would not admit to any materials problem and supply replacement panels free-of-charge. Ultimately, there was no inexpensive and amicable solution for any of the participants in this project. The state declared non-performance and suspended the project engineer, the design architect, and the contractor from bidding on state projects for two years. This resulted in many lawsuits that were resolved to nobody’s satisfaction, but with the vindication of some of the parties. The state ultimately slightly redesigned the memorial, demolished the 1999 construction, and caused a new memorial to be constructed with stone from another source.
The stone panels deteriorated because the dimension stone product was inherently defective at the microscopic level. Saponite, a water-sensitive, swelling clay, is present in the stone. It did not swell in the 1999 Rhode Island drought that followed the installation, but, as soon as it began to rain, the iron-rich saponite absorbed water, causing popouts and stressing the stone until it cracked. Black granite is a stone industry term for black, hard, crystalline rocks such as norite, gabbro, and anorthosite, as compared to fine-grained crystalline rocks such as basalt, or the black varieties of softer calcitic rocks such as limestone or marble. In addition to saponite alteration, the Peribonka® anorthosite contains deleterious ore minerals such as chalcopyrite, younger veins of secondary calcite, and later antigorite veins. The calcite and antigorite veins are weak planes in the stone that cracked when the panels became stressed by the swollen saponite. These natural weak points are not defects, but the natural locus of cracks when the stone was stressed to failure.
Steven Stokowski, a registered Professional Geologist, is the owner and materials geologist of Stone Products Consultants. Steve has extensive geological and petrographic experience across the US. He has a MS in Geology from the South Dakota School of Mines and Technology and a BS in Geology from George Washington University. Steve is the 2014 recipient of the Herbert C. Hoover Award from the Washington DC Section of the Society for Mining, Metallurgy and Exploration (SME), the 2017 Robert W. Piekarz Award from SME, and the Chair of the Industrial Minerals and Aggregates Division of SME. He is Registered or Certified as a Geologist in Georgia, Maine, Virginia and other states.
Tuesday October 27, 2020 at 6:30 pm Eastern Time
“HIDING IN PLAIN SIGHT”: EVIDENCE FOR A MESOZOIC GENESIS OF THE PHREATIC KARST NETWORK IN THE APPALACHIAN GREAT VALLEY” presented by Robert Denton, CPG, of Terracon Consulting.
Ever since the seminal research of William Davis in the early 20th century, the paradigm for the development of Appalachian cavern systems has regarded regional downcutting and lowering of the base level since the Late Miocene epoch as the primary mechanism of speleogenesis. The majority of cave systems were considered no older than the Irvingtonian North American Land Mammal Age (Early through Middle Pleistocene), based on dating of vertebrate index fossil remains found in cavern fill sediments. Nevertheless, since the mid-19th century, there have been reports that suggest the parent phreatic network of the Appalachian Great Valley region may be far older.
Paleogene dates were first suggested for lignite deposits found in karst depressions at Brandon, Vermont, and Pond Bank, Pennsylvania, as early as 1864. Studies of the iron deposits along the west pediment of the Blue Ridge revealed a continuous lineament of karst-related features, often associated with kaolin and lignite. In the 1940s, kaolin and karst bauxite deposits stretching from Virginia to Alabama were discovered. Subsequent palynological analysis of the cave fill and lignite revealed these features ranged from the Turonian stage (93.8 – 89.8 Ma) of the Late Cretaceous through the Early Miocene (20.4 – 16.0 Ma), with most dating from the Early Paleogene.
We propose that the majority of karst-associated laterites (kaolin, bauxite) were probably formed by intense weathering during the Paleocene/Eocene Thermal Maximum (PETM), although a brief period of warming during the Late Miocene may have contributed to the development of laterites present at the Brandon lignite locality. Fossil pollen in karst fills as old as the Turonian stage of the Late Cretaceous suggests an Early Mesozoic age for the probable hypogene speleogenesis of the parent network. Thus, the existing epikarst cavern systems of the Great Valley may be the exposed remnants of an ancient phreatic network that has been repeatedly filled and emptied of sediment since its origin. The recent discovery of karst bauxite in a cave in Virginia suggests that ancient sediments may be more widespread in existing cavern systems than previously thought, but may have been overlooked.
Biography – Robert K. (“Bob”) Denton Jr. was born in 1953 in Montclair, New Jersey. He received his Bachelor’s Degree in Natural Science from Thomas Edison State College in Trenton, NJ in 1988. Bob worked as a research scientist in the chemical and medical device industries for over 20 years, specializing in physical methods of analysis. He relocated to Winchester, Virginia in 1995, and is currently a senior geologist and karst geology “Subject Matter Expert” (SME) with Terracon’s DC Metro office, located in Ashburn, VA. His specialties include environmental science, engineering geology, hydrogeology, and karst characterization, remediation and management. He is considered a national expert on stormwater management in karst terrains.
Bob has been an avid caver since his teen years, and this led to his interest in geology from a very early age. He received formal training in geology and vertebrate paleontology field methods during the summer of 1972 while serving on an expedition to the Bighorn Basin of Wyoming and Montana sponsored by the Museum of Comparative Zoology at Harvard University. Bob is the discoverer of the Ellisdale Fossil Site in NJ, and the Zuni Basin dinosaur site in New Mexico, and has formally described two new taxa. He has been a research associate with the New Jersey State Museum since 1979, and continues in that role today.
Bob is a Certified Professional Geologist (CPG), a State of Virginia Certified Professional Soil Scientist (CPSS) and a State of West Virginia Licensed Environmental Remediation Specialist (LRS). He is a member of the National Speleological Society (NSS), Society of Vertebrate Paleontology (SVP), Association of Environmental and Engineering Geologists (AEG), and the American Chemical Society (ACS). Bob has published numerous articles on subjects including karst, vertebrate paleontology, and materials science. He has been awarded five (5) United States Patents for materials science “discovery of matter” and chemical (process) engineering.
Tuesday, August 25, 2020 at 6:30 pm Eastern Time
Dr. Paul Santi of the Colorado School of Mines.
Geology and the Birth of Landscape Photography: Following Vittorio Sella, Bradford Washburn, and Ansel Adams.
Abstract: The Foothills Art Center in Golden, Colorado hosted an extensive landscape photography exhibit in 2015, including works from Ansel Adams’ Legacy collection, from Vittorio Sella, the early photographer who inspired him, and from Bradford Washburn, the pioneering aerial photographer. Recognizing the importance of geology in these images, the Center contacted the Colorado School of Mines and requested help preparing geology labels to accompany labels written by the curator. Over a five month period, seven students selected by application prepared labels to accompany 37 of the photos, directed by two faculty: a geologist and a science historian. Students independently researched the geology of the photographs, which often required a fair amount of detective work for some of the century-old images. They then wrote, edited, and trimmed the label text, struggling to stay under the 120 word limit, yet keeping the content interesting, unique, and understandable by a lay audience. Every student edited every label at least four times. Alpine scenes dominated, but subjects also included glaciated landscapes, arid terrain, sand dunes, rivers, and contrasts in weathering. The exhibit ran from June 13 – August 30, with several thousand visitors exposed to the linkage between the stunning landscapes and the geology that created them. In this presentation, we will view many of these images, learning the geologic setting, how the geology contributed to the artistic elements of the photo, and how to look at geology from an artist’s eye.
Paul M. Santi
Director – Center for Mining Sustainability
Dept. of Geology and Geological Engineering
Colorado School of Mines
Golden, CO 80401
Tuesday, July 28, 2020 at 6:45 pm
“ITRC’s Characterization & Remediation of Fractured Rock Webinar”
Presented by Kris McCandless, Virginia DEQ
From 2015 to 2018, when it was published online, the Interstate Technology and Regulatory Council (ITRC’s) Characterization and Remediation of Fractured Rock web-based document and subsequent internet-based training have enlightened thousands of new and experienced geologists and environmental scientists with the practical and applicable aspects of structural geology, hydrogeology, and geography that we all had as core classes in our training. I helped to draft portions of the document starting in 2015 when I joined the Virginia Department of Environmental Quality, but more importantly, I was asked in late 2018 to provide the introduction for the internet-based training of this important document. And I have done that at least seven times in the past 2 years, learning something new every time I listen to my fellow speakers present their parts. Knowing not everyone in this audience works in the environmental field, I will focus the training on some of the structurally geologic points as they dictate groundwater flow through the fractured media, and will use examples of “floaters and sinkers” (types of contaminants) in that discussion and why their characteristics are important for investigation and remediation. In my consulting days (25 of my 30 year career), I took it as a compliment that one boss called me a “rabid geologist”, as I kept my Brunton compass and my two types of rock hammer in my field vehicle, always clambering on an outcrop for strike and dip measurements, or standing back from it to find the fracture pattern that would give me a clue to how groundwater might be flowing beneath an impacted site.
From 1998 until about 2012, I was active in AEG (Assoc of Engineering and Environmental Geologists), serving in all offices except treasurer of the local Virginia-Maryland-DC Chapter, where Steve Stokowski and I crossed paths. I graduated from George Mason University in Fairfax, VA in 1988 with a BS in Geology, took Indiana University’s Field Camp in Cardwell, Montana in 1987 and passed the ASBOG exam in Virginia to obtain my CPG license in 2002, which I have maintained. After presiding for many AEG dinner meeting presentations and now here at the Atlanta Geological Society, this will NOT be a boring presentation. There might be one graph, but I’ll cover it quickly!
Notes from the June Meeting:
June 30th, 2020 at 6:45 pm
“Carolina Bays are relict thermokarst lakes from the time of the last glaciation“
Presented by: Dr. Chris Swezey, U.S. Geological Survey, Reston, VA
New studies combining LiDAR imagery and field work have revealed the presence of widespread eolian sands that are now stabilized by vegetation throughout the U.S. Atlantic Coastal Plain. Optically stimulated luminescence (OSL) dates from these sands have yielded ages ranging from ~92–5 thousand years ago (ka), but most of the dates are approximately coincident with the last glacial maximum (LGM). These eolian sands are present in river valleys, in the Carolina Sandhills region, and on upland areas of the northern coastal plain. Eolian sands are also present as low-relief ridges on the south and east margins of Carolina Bays, which are oriented oval to circular depressions on the Atlantic Coastal Plain. Cores in Carolina Bays and their associated ridges reveal that they are primarily surficial features consisting of a few meters of sand and/or muddy sand above an unconformity on various older fine-grained substrates that do not show signs of disturbance. Furthermore, some Carolina Bays show distinct stratigraphic relations with respect to eolian dune fields in river valleys, for example:
(1) Dukes Pond is a Carolina Bay that is inset into (i.e., younger than) eolian dunes in the valley of the Ohoopee River (Tattnall County, Georgia);
(2) Bear Swamp is a Carolina Bay that is inset into (i.e., younger than) eolian dunes in the valley of the Great Pee Dee River (Marion County, South Carolina);
(3) Big Bay is a Carolina Bay that is overlain by (i.e., older than) eolian dunes in the valley of the Wateree River (Sumter County, South Carolina).
Most published OSL ages from Carolina Bay sand ridges range from ~40–11 ka. Some Carolina Bays have multiple sand ridges, and ridges closer to individual bays yield younger OSL ages. The stratigraphic relations and the range of OSL ages suggest that Carolina Bays are relict features that did not form during one event of limited duration. Instead, they formed episodically during the same time interval as other eolian sands of the coastal plain (e.g., mostly during the last glaciation when conditions were colder, drier, and windier). This interpretation suggests that Carolina Bays are relict thermokarst lakes. Such lakes are present today in high-latitude regions, and they develop as a result of thaw and collapse of frozen ground with subsequent modification by lacustrine and eolian processes. Thus, the distribution of Carolina Bays may provide information about the former distribution of frozen ground. Although the southern limit of continuous permafrost during the last glacial maximum (LGM) is usually thought to have been located in northern Virginia ~300 km south of the LGM ice sheet margin, the interpretation of Carolina Bays as relict thermokarst lakes suggests that permafrost may have extended as far south as Georgia ~1000 km south of the LGM ice sheet margin. This distance of ~1000 km from the LGM ice margin compares favorably with studies in Europe (where permafrost is thought to have extended 800-1200 km south of the LGM ice margin) and in Asia (where permafrost is thought to have extended 2000-4500 km south of the LGM ice margin).
Research Geologist (2018-Present), U.S. Geological Survey (USGS) Florence Bascom Geoscience Center, Reston, Virginia. I conduct basic geologic mapping and research on stratigraphy, sedimentology, and geomorphology. This work is focused primarily on Paleozoic basins of the eastern United States, and potential applications for water, energy, and mineral resources.
Research Geologist (2009-2018), USGS Eastern Geology & Paleoclimate Science Center, Reston, Virginia. I conducted basic geologic mapping and research on stratigraphy, sedimentology, and geomorphology. This work was focused on the U.S. Atlantic Coastal Plain, for the purpose of understanding the geologic framework and for characterizing Cretaceous and Cenozoic strata that are major aquifers.
Research Geologist (2000-2009), USGS Eastern Energy Resources Team, Reston, Virginia. I conducted assessments of undiscovered oil and gas resources, and research on stratigraphy and petroleum systems. This work was focused primarily on Paleozoic strata of the Appalachian, Michigan, and Illinois basins (USA), for the purpose of understanding National energy supplies, providing input for economic analysis of petroleum resources, and improving knowledge of the stratigraphy and petroleum systems of the basins.
PG Candidate Workshop
The classes are open to all, membership in the AGS is not required. Please consider joining, the AGS is the most active geologic organization in the Southeast. An application is available here.
Two hours of professional development credit are available for attendees.
Atlanta Geological Society
Professional Registration/Career Development Committee Ken Simonton, P.G.