Category Archives: AEG

AEG-BWH Meeting: Multiple Investigative Methods to Reduce Uncertainty in Karst

Meeting Announcement:
BWH Section of the Association of Environmental & Engineering Geologists

RESERVATIONS:
To reserve a seat, please email Kris McCandless up until Noon on Wednesday, February 19, 2014 at aegbwhsecretary

Date: Thursday, February 20, 2014

TOPIC: Using Multiple Investigative Methods to Reduce Uncertainty in Karst Characterization

PRESENTER: David F. Fenster, PG, Principal Geologist, Eng’g Geology Group Supervisor, Geotechnical & Hydraulic Engineering Group, Bechtel Power Corporation
This subject was presented at the AEG Annual Meeting in Seattle and involved three other authors: W. Godwin (lead author), J. Sowers, and R. Cutsinger.

ABSTRACT:
Characterizing sites underlain by carbonate rock for construction purposes can be tricky at best. When the goal is the construction of critical facilities, it is essential to conduct a site investigation that will result in the reduction of uncertainties to an acceptable level. Carbonate bedrock dissolution can form shallow depressions that initiate at the earth’s surface and propagate in a downward direction, and can form integrated conduit systems at depth. This type of terrain, known as karst, is characterized by dissolution features such as open cavities and fissures, sinkholes, and underground drainage. The hazards to structures built over this type of terrain are well documented. However in cases where karst is not clearly expressed at the surface, for example where the rock is mantled by thick soil, uncertainties in site characterization are increased. Careful geologic characterization using multiple investigative techniques is necessary to facilitate adequate design and mitigate hazard.
In this paper we describe engineering geologic investigations for a nuclear power generating facility sited on carbonate rock in the southern Appalachians, in particular the use of multiple methods to reduce the uncertainty with respect to karst/dissolution hazards at the site. These methods include surface geophysics, vertical and angled borings, surface geologic and geomorphic mapping using LiDAR imagery, statistical analysis of voids, laboratory analysis using XRD/XRF, and development of a site geologic model. Even after the completion of a thorough surface-based investigation, it may be necessary to excavate to foundation depths and to map both floors and walls to further reduce uncertainties.

ADDED SURPRISE: Early indications are that we might be joined at this meeting by several students and their Engineering Geology professor from James Madison University at this meeting. This is encouraging as BWH is hoping to help start a Student Chapter of AEG at JMU.

MEETING INFORMATION:
DATE: Thursday, February 20, 2014
TIME: 6:00 p.m. to 8:45 p.m.
LOCATION – NEW!!
Brewers Alley
124 N. Market Street
Frederick, MD 21701 (Downtown)
Here is the Google Map link to Brewers Alley. (or here: https://maps.google.com/?daddr=124+North+Market+Street,+Frederick,+MD+21701,+USA&p
w=0&t=h&z=16); Parking is either where you can find it on the street, OR, there is a multistory, municipal parking garage directly behind the restaurant (note the long rectangular building east of Brewers Alley when you open the Google Map/Satellite link). Parking garage entrance is off Church Street, a one-way heading east. If coming north on 355/N. Market Street (from I-270), cross over Patrick Street (the divider between N & S street designations), and turn Right on Church, and left into the garage. If exiting I-70 (from Balto, for ex), go north on North on S. East Street, cross over canal, turn left on E. Patrick, Right on
Frederick and Right on Church into garage on left.

COST (dinner & mtg):
Bring personal or company check or cash to the meeting and pay treasurer before presentation.
Members: $35
Non-members: $40
Students: $25
Members, if you’d like to sponsor one of the students’ dinners, that offer will gladly be accepted.
Details on this in subsequent email announcements.

MEETING SCHEDULE:
6:00 to 7:00 pm Social, Networking and Registration
7:00 to 7:45 pm Dinner
7:45 to 8:45 pm Presentation, Questions, Closing Statements

RESERVATIONS:
To reserve a seat, please email Kris McCandless up until Noon on Wednesday, February 19, 2014 at aegbwhsecretary

Steve
S. J. Stokowski
Vice-Chair, AEG-BWH
508-259-3536508-259-3536 cell

Holiday and Christmas Party, AEG-BWH

“Holiday and Christmas Party” Announcement from the BWH Section of the Association of Environmental & Engineering Geologists
Date: Thursday, Dec. 19, 2013

We are doing it again – hosting our 2nd Annual Holiday/Christmas Party of AEG’s Baltimore­‐‐Washington-­‐Harrisburg (BWH) Section for
members, significant others, students and guests. Like last year, this event is more of a party with favors and door prizes than a technical talk. We will have a speaker, Michael Pabst, presenting a talk on “Colorful Rare Earth Minerals”. Rare-­‐earth elements are essential to the beauty of minerals collected by Michael. They are also an essential component of the electronics, batteries, and magnets, many of the gifts exchanged during the
holiday season. His light and colorfully illustrated talk for both the technical and non-­‐technical audience will both delight your eyes and give you an edge on all your “tech-­‐savvy” family members this Christmas. Prior geologic knowledge is NOT REQUIRED but it is adults only, so please
arrange care for your younger family members. As for the November AEG-­‐BWH meeting, it will again be held at Brewers Alley in downtown Frederick, Maryland.

MEETING INFORMATION:
DATE: Thursday, December 19, 2013
TIME: 6:30 p.m. to 9 p.m.

LOCATION and COST:
Brewers Alley
124 N. Market Street
Frederick, MD 21701 (Downtown)

The restaurant/bar faces Market Street, however, the entrance is through a glass enclosure on
the south side. It will be in an upstairs meeting room, so indicate you are with AEG and take
the elevator to the designated floor.
Here is the Google Map link to Brewers Alley. (or here:
https://maps.google.com/?daddr=124+North+Market+Street,+Frederick,+MD+21701, +USA&pw=0&t=h&z=16);
Parking is either where you can find it on the street for free after 5:00 pm, OR, there is a
multistory, municipal parking garage directly behind the restaurant (note the long rectangular
building east of Brewers Alley when you open the Google Map/Satellite link), charging a
maximum of $2 for the duration of the Holiday Party.

Parking garage entrance is off Church Street, a one-way heading east and clearance inside is
7 feet. If coming north on 355/N. Market Street (from I-270), cross over Patrick Street (the
divider between N & S street designations), and turn Right on Church, and left into the garage.
If exiting I-70 (from Balto, for ex), go north on North on S. East Street, cross over canal, turn
left on E. Patrick, Right on Frederick and Right on Church into garage on left.

COST per Person: $40 (or $75 per couple)
RESERVATIONS:
aegbwhsecretary@comcast.net

2012-­14
AEG-­BWH
OFFICERS
Chair: Ashley Hogan, GeoConcepts Engineering, Inc.,
(703) 726-8030(703) 726-8030, ahogan@geoconcepts-eng.com
Vice Chair: Steve Stokowski, Stone Products Consultants.,
(508) 259-3536(508) 259-3536, Ettringite@aol.com
Treasurer: (Open)
Secretary: Kris McCandless, Total Environmental Concepts,
(703) 727-4374(703) 727-4374, aegbwhsecretary@comcast.net

Alberene Soapstone Company Mill Field Trip

Field Trip to the Alberene Soapstone Company Mill
and Quarry in Schuyler, VA
Announcement from the BWH Section of the Association of Environmental & Engineering Geologists
Saturday, March 23, 2013 – Rendezvous at 10 AM, trip from 11 AM – 3 PM
****************************************************************
Soapstone in Central Virginia
Trip Organizers:
Drew Thomas, Peter Farley and Steve Stokowski
ABSTRACT:
Soapstone quarries have been active in Virginia for thousands of years, but the aboriginal quarries were relatively small, producing primarily only bowl and decorative objects. Industrial production for architectural, laboratory, and domestic usage uses began in the Albemarle, Nelson, and Amherst counties
in the late 1800’s. It soon centered in the mill town of Schuyler, VA, which was larger than the county seat.
At one time, the largest company employed over 2,000 people and controlled the mineral rights to over 9,000 acres.
This field trip will visit the mill of the Alberene Stone Company at the location of the original large mill in Schuyler, Virginia, and the quarry currently operated by the company (about 2 miles away).
The products currently produced at the plant include primarily slabs for counter tops and vanities, gauged pavers, flagstones and tiles for interior and exterior applications, and a variety of architectural and commercial specialty sizes. Associated sculptors also carve blocks on special order.
Four color and texture varieties of soapstone are produced. Alberene is a fine-grained, dark charcoal color stone that is very durable. Church Hill is a mottled variety of soapstone that contains residual amphibole. Climax is also a dark stone, but it contains veins of white calcite and some yellow siderite. Old
Dominion is a lighter gray variety with dark veins.
The soapstone occurs as tabular, concordant bodies in the Lynchburg Fm., as does associated serpentinite. These tabular bodies dip steeply to the southeast. The Lynchburg grades from a conglomeratic gneiss to a graphite schist. Most authors conclude that the soapstone bodies are metamorphosed and hydrothermally altered ultrabasic sills. An alternative theory founded upon the
apparently conformable field relationships is that the protoliths were ultrabasic lavas.

Sample collecting is ENCOURAGED, so bring rock hammer, sample bags, cameras

Cost: $30/person (checks or cash accepted at start of field trip, or at March 18 meeting.)
Provided: Box lunch with sodas, water, handout, and lotsa quarry time!
Must Bring/Wear: Mandatory hard-toed boots or shoes. Some hard hat and safety glasses available but bring your own so you can be styling.
Attendee Limit: 35
Box Lunch Choices:
Box lunches will consist of a sandwich, chips, pickle and cookie or brownie, with a beverage selection, including bottled water, provided by AEG-BWH. With your reservation, I need your choice of meat/vegetarian and bread:
Meat: Smoked Turkey — Roast Beef — Premium Ham — Chix Salad with Almonds and pineapple
Vegetarian: Spinach VeggieWrap: Organic wheat wrap stuffed with organic spinach, guacamole and pico, mushrooms and asiago.
Bread: White — Whole Grain Wheat — Rye
(Turkey on Whole Wheat is default if no choice made from list of above).
RESERVATIONS:
To reserve, please email Kris McCandless no later than Noon, Thursday, March 21, 2013 at aegbwhsecretary@comcast.net and give me MEAT and BREAD selections, or, VEGETARIAN

PRIMARY RENDEZVOUS POINT
Meet us in the parking lot between 9:45 and 10:15 am in the parking lot of the Stultz Center, Piedmont Community College, Charlottesville, VA.
We will gather everyone together and caravan down to the soapstone company where we will meet Peter Farley. We will leave no later than 10:15. If you are running late and do not make the rendezvous point, you may call either Steve or Kris’s cell phones for directions:

Steve Stokowski at 508-259-3536
Kris McCandless at 703-727-4374

AEG: McCalpin on paleoseismology

Joint AEG-GSA Richard Jahns Lecture one week from today (oops, it’s Tuesday now, so THIS COMING MONDAY) at George Mason University in Fairfax, VA (at the Johnson Center). The Jahns Lectures are aimed at students in the geological fields but there’s always we professionals who can pick up a thing or two at these lectures, I’ve found.

The Jahns Lecturer this year is James McCalpin, who will be discussing Paleoseismology. Check inside the attached announcement for details on Mr. McCalpin and come to GMU this coming Monday to learn about Paleoseismology! Free pizza, beverages and a cash bar will be provided.

For everyone wishing to attend, please let me know so I can get a count for the pizzas and beverages. Email Kris aegbwhsecretary@comcast.net  by Friday, close of business, March 15. Thanks

AEG: Fukushima Response Actions for US Nuclear Plants Flooding Re-Evaluations

http://www.aegweb.org SECTION MEETING: Baltimore MD – Washington DC – Harrisburg PA
Toipic: Fukushima Response Actions for US Nuclear Plants Flooding Re-Evaluations
PRESENTER: Kit Y. Ng, Bechtel Power Corporation, Frederick, MD
Kit Ng is a senior principal hydraulic and hydrology specialist and also serves as the assistant chief of Bechtel Power Corporation’s Geotechnical & Hydraulic Engineering Services Group. She has 22 years of industry experience and is the technical lead in Bechtel Power on hydrologic and hydraulic design and
modeling, specifically on flooding hazard evaluation for nuclear power facilities, design of cooling water systems, intake and outfall hydraulic design, water resource management, storm water management, site drainage, erosion & sediment controls, coastal hydrodynamics and contaminant mixing and transport modeling in both surface water and groundwater. Kit has a PhD in environmental hydraulics from the California Institute of Technology. She has served as the chair for the Computational Hydraulic Committee of ASCE/EWRI and is currently a member of the ANSI/ANS 2.8 and 2.31 standard committees on design basis flood determination for nuclear facilities and estimating extreme precipitation at nuclear facility sites. She is also participating in the new ANS 2.18 standard committee on evaluating radionuclide transport in surface water for nuclear power sites.

ABSTRACT: In response to the accident at the Fukushima Dai-ichi nuclear power plant resulting from the March 11, 2011, Great Tohoku Earthquake and subsequent tsunami, the Nuclear Regulatory Commission established a Near-term Task Force (NTTF) to review the existing regulatory process and
regulations. The NTTF concluded that, with the current regulatory approach and the resultant plant capabilities, an accident with consequences similar to the Fukushima accident is unlikely to occur in the United States. As part of the review, the task force also developed a comprehensive set of 12 recommendations that they believe are necessary to strengthen nuclear safety. These recommendations, with both short and long term elements, span across many areas from loss of electrical power to earthquakes, flooding, spent fuel pools, venting and emergency preparedness. Among them, Recommendations 2.1 and 2.3 on flooding and seismic reevaluations and walkdown were identified in September 2011 and approved by the Commission in October 2011 as actions to be implemented without unnecessary delay. This presentation will focus on the implications to the nuclear industry of Recommendation 2.1 on flooding reevaluation.

MEETING INFORMATION:
DATE: Thursday, February 21, 2013
TIME: 6:00 p.m. to 9:00 p.m.
LOCATION NEW!!
Holiday Inn
5400 Holiday Drive
Frederick, MD 21703
(At I-270 & Buckeystown Pike MD-85. Access Holiday Drive by entering Francis Scott Key Mall from MD-85, shown here on Google maps: http://goo.gl/maps/b8Pp2) If coming north on I-270, you’ll see the Holiday Inn on your right; almost opposite the Hampton Inn.
COST (dinner & mtg):
Members: $30
Non-members: $35 (If you become a member before the day of the meeting, the charge will be $30)
Students: $20
MEETING SCHEDULE:
6:00 to 7:00 pm Social, Networking, Cash Bar (IS BACK!) and Registration
7:00 to 8:00 pm Dinner
8:00 to 8:30 pm Presentation
8:30 to ? pm Questions, Closing Statements

 

RESERVATIONS:
To reserve a seat, please email Kris McCandless No Later Than 10:00 AM Monday, February 18, 2013 at aegbwhsecretary@comcast.net – No-shows will be invoiced!

Save the Dates:
March 19: Richard Jahns Lecturer James McCalpin (location TBD, probably George MasonUniversity)
March 23: Saturday FIELD TRIP to Alberene Soapstone Company, Schuyler, Nelson County, VA (details to follow)
April 18: Matt Morris, Gannett Fleming and AEG President. “The History and Progression of Rock Slope Stabilization for Menoher Boulevard (aka Easy Grade Highway or S.R. 271, Section 13), Cambria County, Pennsylvania”
May 16: TBD

AEG: Fracking and fluid-induced earthquakes

Notice of Meeting
Announcement from the BWH Section of the
Association of Environmental &
Engineering Geologists
Date: Thursday, Jan. 17, 2013
http://www.aegweb.org
SECTION MEETING
Baltimore MD – Washington DC – Harrisburg PA
Toipic: Earthquakes Induced by Fluid Injection
PRESENTER: William (Bill) Leith, Ph.D., US Geological Survey, Reston, VA
Bill Leith is the Senior Science Advisor for Earthquake and Geologic Hazards at USGS. In this position, he
oversees the Earthquake Hazards, Geomagnetism, and Global Seismographic Network (GSN) Programs.
Leith joined the USGS in 1986, after receiving a doctoral degree in seismology and geology from Columbia
University, and a bachelor’s degree from the University of California at Berkeley. He served USGS as Chief
of the USGS Special Geologic Studies Group from 1990–2001, as Senior Technical Advisor to the Assistant
Secretary of State for Verification and Compliance, from 2001–2003, as the Coordinator of the Advanced
National Seismic System from 2003–2012, and as USGS Acting Associate Director in 2010–2011.
In recent years, as Associate Coordinator of the Earthquake Hazards, Geomagnetism, and GSN Programs,
Leith has led the development of the Advanced National Seismic System and the completion of the GSN.
Leith has over 100 publications in the areas of seismology, geology, engineering geology, tectonics, and the
applications of these subjects to earthquake safety, response and engineering, as well as to nuclear
weapons testing and test monitoring, treaty verification and compliance assessments, and other military and
national security interests.
ABSTRACT: To produce natural gas from shale formations, it is necessary to increase the
interconnectedness of the pore space (permeability) so that the gas can flow through the rock mass and be
extracted through production wells. This is usually done by hydraulic fracturing (“fracking”). In addition to
natural gas, fracking fluids and formation waters are returned to the surface. This wastewater is often
disposed of by injection into deep wells. The injection of wastewater deep into the subsurface can cause
earthquakes that are large enough to be felt and may cause damage. Only in very rare cases does fracking
cause small earthquakes, but they are almost always too small to be a safety concern. Of more than
150,000 Class II injection wells in the United States, roughly 40,000 are waste fluid disposal wells from oil
and gas operations. Only a small fraction of these disposal wells have induced earthquakes that are large
enough to be of concern to the public. Of the case histories for which there is a scientific consensus that an
injection operation induced earthquakes, the largest are just above magnitude 5. USGS scientists have
investigated a recent sharp increase in the number of magnitude 3 and larger earthquakes in the
midcontinent of the United States. These earthquakes are large enough to be felt by many people but are
small enough that they rarely cause damage. The average number of earthquakes occurring per year of
M3 or greater increased starting in 2001, culminating in 2008-2011 with a six-fold increase over 20th
century levels. Nearly half of these earthquakes are occurring in areas where hydraulic fracturing, and
hence wastewater disposal, is known to be occurring.

MEETING INFORMATION:
DATE: Thursday, January 3, 2013
TIME: 6:30 p.m. to 8:30 p.m.
LOCATION and COST:
Hampton Inn (conference room, TBD)
5311 Buckeystown Pike
Frederick, MD 21704
(At I-270 & Buckeystown Pike MD-85)
COST (dinner & mtg):
Members and non-members: $30
Students: $20
MEETING SCHEDULE:
6:30 to 7 p.m. Social and Registration
7 to 7:45 p.m. Dinner
7:45 to 8:30 p.m. Presentation
8:30 – ? p.m. Questions, Closing Statements
RESERVATIONS:
To reserve a seat, please email Kris McCandless by close of business Tuesday, January 15,
2013 at aegbwhsecretary@comcast.net

AEG Christmas and Holiday Party

“Holiday and Christmas Party”
Announcement from the BWH Section of the
Association of Environmental &
Engineering Geologists
Date: Thursday, Dec. 20, 2012

Join your AEG-­‐BWH friends for a night of good laughs, great company, cool gifts, and yummy food. Then take off on a transcontinental sleigh ride of geological discovery as you make a new friend, Callan Bentley, who will take us from Giant City in Illinois to the Kansas chalk and then to the towering Rockies and the fossils they hide. North America’s geologic wonders will be shared in Callan’s amazing “Two months of rock and road” presentation. Callan Bentley is an Assistant Professor of Geology at Northern Virginia Community College in Annandale. He is the author of the popular geology blog Mountain Beltway. He has won multiple awards and is the 2012 recipient of the Chancellor’s Award for Teaching Excellence. Prior geologic knowledge is NOT REQUIRED to attend this party: all will be amused. We also want to meet your spouses and significant, or even casual, others. Besides Callan’s exciting and scenic talk, there will be door prizes and goodies to be won throughout this night of geologic discovery.

MEETING INFORMATION:
DATE: Thursday, December 20, 2012
TIME: 6:30 p.m. to 10 p.m.
LOCATION and COST:
Hampton Inn
5311 Buckeystown Pike
Frederick, MD 21704
(At I-270 & Buckeystown Pike MD-85)
COST per Person: $35
RESERVATIONS:
To reserve a seat, please email Kris McCandless at AEGBWHsecretary@comcast.net

2012-­14
AEG-­BWH
OFFICERS
Chair: Ashley Hogan, GeoConcepts Engineering, Inc.,
(703) 726-8030, ahogan@geoconcepts-eng.com
Vice Chair: Steve Stokowski, Stone Products Consultants.,
(508) 259-3536, Ettringite@aol.com
Treasurer: Drew Thomas, ECS Ltd, (703) 471-8400,
dthomas@ECSLimited.com
Secretary: Kris McCandless, Total Environmental Concepts,
(703) 727-4374, aegbwhsecretary@comcast.net

AEG November mtg: metamorphic rocks of the Piedmont in Montgomery County, MD

The Baltimore-Washington-Harrisburg Section of AEG is holding our November meeting on Thursday, the 15th (NEXT THURSDAY!!) at the Pastimes Cafe (within the Hampton Inn) up in Frederick, MD, with happy hour and networking starting at 6 pm, dinner at 7, and presentation at 8 pm.

AEG-BWH member, Professional Geologist, and Professional Engineer, Paul Headland, will refresh and renew our knowledge of the local metamorphic rocks of the Piedmont in Montgomery County, Maryland for a 5-Mile water tunnel project. This is pure Engineering Geology – who doesn’t love a good tunneling project, right? Tell your friends to join us next Thursday night.

Save the date: December 20 at Pastimes/Hampton for AEG-BWH’s First (in a long time) Christmas Party.

AEG meeting: Nitrates in Rural Groundwater

Notice of Meeting
Announcement from the BWH Section of the
Association of Environmental &
Engineering Geologists
Date: Thursday, October 18, 2012
http://www.aegweb.org
SECTION MEETING
Baltimore MD – Washington DC – Harrisburg PA
Topic: Nitrates in Rural Groundwater Supply Wells Not from Farming:
An Unexpected Finding Based on Forensic Hydrogeology
PRESENTER: Mark W. Eisner, P.G., President, Advanced Land & Water, Inc.
ABSTRACT: Sharptown is located in an agriculturally dominated portion of the Delmarva Peninsula and is supplied by four wells. Groundwater quality compliance samples have reflected elevated nitrate concentrations for years. Non-point agricultural sources were thought to be the source of the nitrates, but detailed study as a component of an updated Source Water Protection Plan assessment now has revealed a differing and surprising interpretation. For our source water assessment work, we analyzed available water quality data via End-Member Mixing Analysis. EMMA is a common surface water investigative technique; its use to interpret groundwater contaminant sources and contributions is less common. We used chloride and nitrate as tracers,
based on the limited compliance data available. The lack of known septic systems near the wellfield, seasonality of nitrate concentration fluctuations and historic reports of sewer system leaks suggest that the nitrate may originate more from a local sewer system leak than from historic and regional farming. Work is ongoing and we are sampling for indicators of detergents and
domestic sewage. If the sewer system leak suggested by these findings is confirmed, its repair may offer a more economical means of nitrate reduction than treatment and a more assured means than encouraging changes in long-standing local agricultural practices.
Mark is an enthusiastic, lively speaker, presenting the latest groundwater hydrogeological analysis and testing tools available to hydrogeologists and environmental scientists.

MEETING INFORMATION:
DATE: Thursday, October 18, 2012
TIME: 6 p.m. to 9 p.m.
LOCATION and COST:
Pastimes Café (inside Hampton Inn)
5311 Buckeystown Pike
Frederick, MD 21704
(At I-270 & Buckeystown Pike MD-85)
COST (dinner & mtg):
Members and non-members: $30
Students: $20
MEETING SCHEDULE:
6 p.m. to 7 p.m. Social Hour and Section Business
7 p.m. to 8 p.m. Dinner
8 p.m. Presentation
9 p.m. Closing Statements
RESERVATIONS:
To reserve a seat, please email Kris McCandless no later than (NLT) NOON Wednesday, October 17, 2012 at aegbwhsecretary@comcast.net .

AEG field trip: Back to the Tonian!

Notice of Field Trip
At the Lehigh Cement Mill & Quarry,
Union Bridge, MD
Announcement from the BWH Section of the
Association of Environmental & Engineering Geologists
Saturday, October 27, 2012
10 AM – 3 PM
****************************************************************
A Trip Back to the Tonian: 960 Ma Volcanism and Microbialites
in the Westminster Terrane of Maryland
by:
Liz Graybill and Bob Ganis
ABSTRACT: The Sams Creek/Wakefield Complex in the Westminster Terrain of Maryland includes highcalcium,
low-magnesium limestone exploited in the vicinity of Union Bridge for cement production.
Stratigraphic, geochemical, petrographic and radiometric dating analyses of new exposures revealed an
elegant geologic history.
The stratigraphic studies showed that the interlayered carbonates, metabasalts, phyllites, and rare
sandstone channels were contemporaneously deposited. Continuous deposition of carbonate rocks
containing biogenic microbialite layers which also contain non-carbonate ash falls, lava flows, and
pyroclastic debris. Both basaltic and andesitic rocks erupted.
New zircon dates reveal a 950-970 Ma age for the sequence. These were acquired from three
units: basaltic greenstone representing the floor of the carbonate buildup, andesitic meta-ash (phyllite)
layers within the carbonate rocks, and a quartz sandstone channel within the carbonate sequence. The
metabasalt preserved 1036-1269 Ma zoned Grenville xenocrysts. The meta-ash hosted two zircon
populations: 1016-1321 Ma zoned plutonic sourced xenocrysts, and unzoned 950-970 Ma eruptive ages.
The sandstone channel preserved prismatic (944-1553 Ma) and rounded (969-1537 Ma) zircons. The
zircon populations came from both Grenville aged rocks, with zoned zircons, and from contemporaneous
volcanics, which contained unzoned zircons. No zircons younger than 944 Ma were found.
We propose that these rocks formed when Rodinia was breaking up following Grenville orogenesis,
with the development of a rift feature at ~960 Ma. The trace element composition of greenstones resembles
within-plate through plate-boundary-enriched, mid-ocean ridge basalt (EMORB), possibly tracking the
opening of a rift basin. In addition, the chemical composition of the Sams Creek meta-volcanics is similar to
other known rift volcanics. Prior hypotheses that the Sams Creek volcanics were either Catoctin related (at
~570 Ma) or were formed as Cambro-Ordovician oceanic islands with atolls (Wakefield carbonate) are not
supported by the age dates and stratigraphic relationships.
Google Map of Union Bridge & Field Trip: http://goo.gl/maps/pP5Rr
Page 1 of 2
Page 2 of 2
Sample Collecting is ENCOURAGED, so bring rock hammer, sample bags, markers,
cameras
Cost: RSVP required because we need to print a guidebooks and purchase food and
beverages. $45/person (checks or cash accepted at start of field trip, or at the October
18 meeting.) Email Kris your RSVP & lunch choice. aegbwhsecretary@comcast.net
Provided: Handout/guidebook, box lunch with sodas & water, van to visit the stops,
rock samples!
Must Bring/Wear: Mandatory hard-toed boots or shoes. Some hard hat and safety
glasses available, but bring your own so you can be styling.
Attendee Limit: 48
Box Lunch Choices:
􀀀 Ham (applewood smoked) and provolone cheese garnished with lettuce, tomato, and mayo
􀀀 Turkey breast, topped with lettuce, tomato, alfalfa sprouts, and mayo
􀀀 Roast beef (medium rare, shaved), topped with mayo, lettuce, and tomato (default if none checked!!!)
􀀀 Vegetarian – Layers of provolone cheese separated by real avocado spread, alfalfa sprouts, sliced
cucumber, lettuce, tomato, and mayo
All are an 8” homemade French bread sub topped with shredded lettuce, fresh tomatoes, and mayo. Also
includes chips, cookie, pickle.
(Turkey is default if no choice made from list of above).
RESERVATIONS:
To reserve, please email Kris McCandless no later than Noon, Wednesday, October 24, 2012 at
aegbwhsecretary@comcast.net and please select one of the sandwich choices above.
(Turkey is default if no choice made from list of above).
Town of Union Bridge is in Carroll County, Maryland, 21791
Meet at the Main Office of the Lehigh Cement Company, paved parking is provided.
Plant Entrance: Lat
39⁰
33.518”
N
;
Long
77⁰
10.019
W
Main Office: Lat
39⁰
33.690”
N
;
Long
77⁰
10.245
W
2012-14 AEG-BWH OFFICERS
Chair: Ashley Hogan, GeoConcepts Engineering, Inc.,
(703) 726-8030, ahogan@geoconcepts-eng.com
Vice Chair: Steve Stokowski, RJ Lee Group, Inc.,
(508) 259-3536, sstokowski@rjlg.com
Treasurer: Drew Thomas, ECS Ltd, (703) 471-8400,
dthomas@ECSLimited.com
Secretary: Kris McCandless, Total Environmental Concepts,
(703) 727-4374, aegbwhsecretary@comcast.net