Monthly AGS Meeting
Join us Tuesday, July 28, 2020 at 6:45 pm for a Virtual AGS Meeting on Zoom. https://us02web.zoom.us/j/89579296351
Presentation at 7 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 for a Virtual AGS Meeting on Zoom.
Join Zoom Meeting
“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).
Christopher S Swezey
Florence Bascom Geoscience Center
U.S. Geological Survey
12201 Sunrise Valley Drive, MS 926A
Reston, VA 20192
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.