Author Archives: Callan Bentley

Romans on deep-sea paleoclimate records



Ocean circulation plays a critical role in the Earth’s climate system through the storage and transfer of heat and carbon dioxide. The North Atlantic and Southern Ocean are of particular interest because these are regions where deep-water components of global circulation develop. Overall patterns and functioning of modern oceanic circulation is relatively well understood, but significant uncertainty remains about circulation in the geologic past and during different climate regimes. Dr. Romans uses the deep-sea sedimentary record to reconstruct past ocean circulation and its relationship to past climatic and tectonic conditions. He integrates information from a broad range of spatial and temporal scales, from seismic-reflection data that reveals regional sedimentation patterns to high-resolution records based on quantitative grain-size analysis from cores. Dr. Romans will present research from the North Atlantic Ocean (Expedition 342, Newfoundland Drifts) that shows how vast deep-sea “drift” deposits relate to the onset of and changes in ocean circulation in the Eocene through Miocene. In addition to his work on the North Atlantic, Dr. Romans will also present preliminary findings from new drilling (January-February 2018) in the Ross Sea (Expedition 374, West Antarctic Ice Sheet History), which aims to study interactions of Southern Ocean circulation and Antarctic ice sheet dynamics during significant climate events of the Miocene and Pliocene.

Dr. Romans is an associate professor in the Department of Geosciences at Virginia Tech. He received his Ph.D. in Geological & Environmental Sciences from Stanford University, M.S. in Geology & Geological Engineering, and undergraduate degree in Geology at SUNY Buffalo. Brian participated as a shipboard scientist on two IODP Expeditions (Expeditions 342 and 374).

Seminar is at 12pm on Friday, October 12 in the CE Forum, NOVA Annandale campus, as part of the OCEAN DISCOVERY LECTURE SERIES and the MTSB SCIENCE SEMINAR SERIES.
Please join us for refreshments and a fascinating talk.


UMD: NASA’s Kirschbaum on remote sensing of landslides

2018 University of Maryland Geology Colloquium Series

Friday, September 21st 2018 at 3:00 pm
in PLS 1130, UMD College Park

Dalia Kirschbaum
NASA Goddard

Finding the Slippery Slope: “Detecting” Landslides from Space

Rainfall-triggered landslides occur in nearly every country around the world, causing billions of dollars of damages and cause thousands of fatalities each year. Understanding and modeling the dynamics of rainfall-triggered landslides is a challenging task due to rainfall variability and the complexity of approximating landslide failure mechanisms over broader scales. Satellite data provides a unique perspective to estimate where and when landslides may be occurring as well as to map areas when these events occur. However, the accuracy is highly dependent on the spatial scale and methods used. This presentation outlines several on-going efforts to better understand landslide activity at different spatial and temporal scales using different modeling, mapping and citizen science methods.

GSW’s 2018 Bradley speaker announced: Oct 3

GSW meeting 1533: Wednesday, October 3

~ The 2018 Bradley lecture ~

Jane Willenbring
Scripps Institution of Oceanography
“Not Feeling the Buzz: Tectonics – Not Climate – Limits Heights of Mountains”


The potential to rapidly denude topography at and above the glacier Equilibrium Line Altitude (ELA), irrespective of uplift rates, rock type or pre-existing topography, is explored in the glacial buzzsaw hypothesis. In this talk, I offer evidence from cosmogenic nuclide data and numerical models that (1) topography can persist in a state of transience for millions of years through feedbacks that can promote and maintain subdued topography dissected by valleys and that (2) the glacial buzzsaw cuts down–not across. Finally, we compiled tectonic, topographic, and erosion rate data from Arc-Continent convergent margins where the convergence rate is known (Andes, Central America, Cascadia, British Columbia, Alaska, Taiwan, and Makran). Erosion rates and elevation maxima and mean elevations correlate linearly with plate convergence rates. Importantly, mountain peaks in three heavily glaciated mountain ranges (Alaska, Cascadia, and South Chile) do not deviate from the trend of unglaciated mountain ranges such as the Central Andes and Taiwan. That mountain ranges with different climatic characteristics fall within the same trend implies that tectonics is the primary control of mountain range mass and heights–not glaciers.SIO_Willenbring_headshot250

Jane Willenbring is an Associate Professor at Scripps Institution of Oceanography, UC San Diego. She joined Scripps in the summer of 2016 and is the Director of the Scripps Cosmogenic Isotope Laboratory. She received her B.Sc. from North Dakota State University, where she was a McNair Scholar, and a Master’s degree from Boston University. She received her Ph.D. in Earth Sciences from Dalhousie University in Halifax, Nova Scotia Canada and was named an Izaak Walton Killam Laureate. She was a Synthesis Postdoctoral Fellow through the National Center for Earth-Surface Dynamics, and an Alexander von Humboldt Fellow at GFZ Potsdam, Germany. Jane was previously a professor at the University of Pennsylvania and a Blaustein visiting professor at Stanford University. She is a Fellow of the Geological Society of America and in 2016 was awarded an NSF Career grant.

Beverages and socializing commence at 7:30pm.
The formal program starts at 8:00pm.
Meetings are open to the public; please join us!

We meet in the John Wesley Powell Auditorium of the Cosmos Club,
2170 Florida Avenue NW, Washington DC 20008.

Entrance is through the club gate, the first right-hand entrance on Florida Avenue north of the intersection with Massachusetts Avenue NW. The auditorium entrance is to the left of the gate. The Powell Auditorium is within walking distance of the DuPont Circle Metro stop (Q Street exit), the Connecticut Avenue bus routes (L2, L4), and the Massachusetts Avenue bus routes (N2, N4).

PSW: DeMar on amphibians and non-dino reptiles during the K/PG

The Paleontological Society of Washington

7:00 pm, Wednesday, September 19

National Museum of Natural History, Constitution Ave. entrance

Amphibians, lizards, and snakes from the Age of Dinosaurs and the end-Cretaceous mass extinction

David G. DeMar, Jr.
Postdoctoral Research fellow, Paleobiology Dept., Smithsonian Institution.

The Cretaceous-Paleogene (K-Pg) mass extinction, which famously led to the demise of the non-avian dinosaurs, redirected the evolutionary trajectory of life on Earth. Here, I present on how salamanders, lizards, and snakes, a largely overlooked aspect of the vertebrate faunas from this critical time interval, fared during that extinction event. Moreover, these ecologically sensitive taxa or the proverbial ‘canaries in a coal mine’ serve as a litmus test for testing the climate-driven hypotheses of the K-Pg mass extinction.

Non-Smithsonian visitors will be escorted from the Constitution Ave. entrance of the NMNH to the Q?rius theatre at 6:50 and 6:55 p.m. Society members will host the speaker for dinner at the Elephant & Castle (1201 Pennsylvania Ave.) prior to the meeting. Members may meet at the restaurant or inside the Constitution Ave. entrance of the NMNH at 5:00 and walk to the restaurant as a group. Parking is available in the west side parking lot of the NMNH.

AEG: Bentley on geo-visualization

Association of Environmental & Engineering Geologists

D.C. – Maryland – Virginia Chapter (

Thursday, September 20, 2018, from 5:30 PM to 8:00 PM at Amphora Restaurant in Vienna, VA.

AEG Members $40, Non-members $45 (includes dinner; student and retiree discounts available). Please register by Monday, September 17, via online payment (

Presenter:         Callan Bentley, Assistant Professor of Geology, Northern Virginia Community College

Title:  Visualization in Geology

Lore has it that a picture is worth a thousand words. But whether this is the correct “exchange rate” depends on the quality of the picture. What makes for an effective geological visualization? Where do poor geo-visualizations go astray? Where has geo-visualization come from, and where is it going? Callan Bentley has been a prominent public-facing geo-visualizer for more than a decade. His posts on the geoblog “Mountain Beltway” are heavily imagery-dependent, and here he shares some lessons learned. Derived from Bentley’s presidential address to the Geological Society of Washington, this talk will cover:

1)  Historical milestones over the past 500 years in making pictures of geological content

2)  Best practices in making graphics

3)  Best practices in geological photography

4)  Advances in the digital age, with an emphasis on Bentley’s work in GigaPans, 3D models from photogrammetry, and virtual field experiences

Callan Bentley is an assistant professor of geology at Northern Virginia Community College’s Annandale campus. His academic background includes a BS in geology at the College of William & Mary (1996), an MS in geology from the University of Maryland, College Park (2004), and an MS in Science Education from Montana State University (2009). Since starting at NOVA in 2006, Callan has given almost a 100 public talks and field trips at venues across the Metro region and another 100 talks or posters at professional meetings around the country and the world. In additional to publishing in the professional scientific literature, Callan is a Contributing Editor for EARTH magazine, contributing book reviews, travel stories, and cartoons. He has served as newsletter editor for the two-year-college division (Geo2YC) of the National Association of Geoscience Teachers (3 years) and the eastern section of NAGT (2 years and counting), and is now the President of the Geo2YC Division of NAGT. Callan is the Past President of the Geological Society of Washington, and has previously served GSW as Councilor, Meeting Secretary, Executive Secretary, and Vice President. In addition to writing his popular geology blog Mountain Beltway, Callan was a contributor to five geology and Earth science textbooks published by Pearson and is under contract to write another as lead author. He has become known as an innovator in digital geology, in particular for the use of GigaPan images of outcrops and samples, a technique that allows “virtual field experiences” for distance learners and students with disabilities.

Please refer to our meeting announcement for full details.

2018 VGFC registration open

Registration is now open for the 2018 Virginia Geological Field Conference,  A yearly conference highlighting Virginia’s geological diversity:

This year’s field trip will focus on the geology of the Southside Virginia Piedmont.  Yes, Virginia there are rocks exposed in the Southside Piedmont! The 2018 conference will highlight new geochemical, geochronological, and structural insights into the geologic history of terranes in the southeastern-most Piedmont including the Roanoke Rapids, Raleigh, and Carolina terranes.  The conference will be based out of Petersburg, and the field trip will venture as far south as Skippers, near the Virginia-North Carolina state line.


The 48th Virginia Geological Field Conference will meet in Petersburg, Virginia at the Holiday Inn Express & Suites Petersburg/Dinwiddie. The hotel is located off I-85 and near US Rt. 460 on the southwest side of Petersburg.


Student Geoscience Career Mentoring Workshop—3 to 5 p.m., Friday, October 26, hotel conference room.  Open to all two-year, four-year, and graduate college students.

Reception, Business Meeting, and Field Trip Introduction – 6 to 8 p.m. at the hotel meeting room

The Field Trip – Saturday, Oct. 27 departure at 7:30 a.m. from Holiday Inn Express & Suites Petersburg/Dinwiddie. Return by 6 p.m.

The field trip will include a traverse across the Southside Virginia Piedmont, stops will include the Petersburg Granite, mafic and felsic rocks in the Roanoke Rapids terrane, Skipper Granite quarry, and the Falls of the Nottoway.  We’ll have lunch in Emporia, Virginia. Participants should wear sturdy shoes, and dress for Fall weather in the Piedmont.  Hard hats are needed for the quarry visit.  Weather permitting, participants may wish to immerse themselves (or some part of themselves) in the Nottoway River.  There will be some walking over rough terrain, the longest walk will be ~1/2 mile.


Professionals – $75 or $80                           Students – $25 or $30

Participants can pay beforehand with check for $75/$25 students (payable to Virginia Geologic Field Conference, c/o Mark Carter, 3391 West Old Mountain Road, Louisa VA), or use Eventzilla for $80/$30 students. Register early as there will not be on-site registrations. Students, if paying by check, please indicate whether or not you are planning to attend the Friday afternoon Student Forum/Workshop in addition to the Saturday Field Trip.  Also, be prepared to show a current Student ID at check-in.

Registration fees include food/drink at the reception, transportation for the field trip, lunch, beverages, and snacks on Saturday.


Current prices for the Holiday Inn Express & Suites Petersburg/Dinwiddie are ~$100 for double rooms.  Book early.

There are other hotel options in Petersburg. Camping and cabins are available at Picture Lake Campground (~10 minutes from the Holiday Inn Express).

UMD: Carnegie’s Shimizu on mantle carbon

2018 University of Maryland Geology Colloquium Series

Friday, September 14th 2018 at 3:00 pm
in PLS 1130 (UMD- College Park)

Kei Shimizu
Carnegie DTM

Carbon contents in Earth’s mantle domains constrained using silicate melt inclusions and geochemical modeling

Estimates of carbon contents in mantle sources of mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs) can provide constraints on the origin of the geochemically heterogeneous mantle. Furthermore, carbon fluxes from MORB and OIB mantle sources to the atmosphere provide constraints for understanding Earth’s climate stability and habitability. However, carbon contents in these mantle sources are difficult to estimate since most MORBs and OIBs have lost significant portions of their CO2 through degassing. Silicate melt inclusions, which are small amount of quenched magma trapped in crystals, preserve the CO2 contents in MORB and OIB magmas at depths of melt inclusion entrapment prior to significant CO2 degassing. In this talk, I will discuss carbon contents for MORB mantle sources (Siqueiros and Garrett transform fault in the East Pacific Rise) and an OIB mantle source (Borgarhraun in northern Iceland) estimated u! sing data from silicate melt inclusions in combination with geochemical modeling of mantle melting, magma degassing and mixing. The preliminary results suggest that the Iceland mantle source (~400 ppm CO2) may be significantly more carbon-rich compared to an EPR-type MORB mantle source (~100 ppm CO2).