Callan demonstrates for Field Studies Students (Billy Goat Trail) students how a quartz vein can get folded twice. Great Falls Overlook, Olmstead Island, C&O Canal National Historical Park, Maryland.

Photograph by Kevin Mattingly.

March 2008

Field Studies Students (Billy Goat Trail) student Maitland Sharpe examines the amphibolite exposed along the Billy Goat Trail's "emergency exit" trail. Is this a metamorphosed mafic sill or a tectonic sliver of the Iapetus Ocean crust?

Photograph by Kevin Mattingly.

March 2008

Callan shows Field Studies Students (Billy Goat Trail) the migmatite along side of the Billy Goat Trail: evidence that these rocks were once very hot and rather deep in the Earth.

Photograph by Kevin Mattingly.

March 2008

Students on the Billy Goat Trail field course examine the rocks exposed along Mather Gorge.

Photograph by Kevin Mattingly.

March 2008

Callan and Field Studies Students (Billy Goat Trail) check out the lamprophyre dikes exposed at the head of Mather Gorge, C&O Canal National Historical Park.

Photograph by Kevin Mattingly.

March 2008

Honors students pose with an original copy of William Smith's geologic map (one of only two in the United States) at the northeastern section meeting of the Geological Society of America meeting in Buffalo, New York.

March 2008

The Spring 2008 Historical Geology class poses with spring foliage on their field trip to Washington, DC.

April 2008

Physical geology students attempt to deduce the cause of strange, parallel grooves in the Seneca sandstone used to build the locks of the C&O Canal. The grooves are all parallel to the canal's trend, and have rounded profiles in cross-section. Can you guess what made them? Highlight (select) below for the answer: rope burns caused by mules pulling barges along the C&O Canal.

Photograph by David Sloan.

November 2007

NOVA geology Honors student Anastassia Bogosian-Scissors collects samples of limestone which are reported to contain silicified trilobite fossils, south of Strasburg, Virginia (in the Shenandoah Valley). Field work is an option for Honors students on their individual research project.

November 2007

NOVA geology Honors student Victoria Martin helps collect samples of limestone which are reported to contain silicified trilobite fossils, south of Strasburg, Virginia (in the Shenandoah Valley). Field work is an option for Honors students on their individual research project.

November 2007

NOVA geology Honors student John Weidner helps collect samples of limestone which are reported to contain silicified trilobite fossils, south of Strasburg, Virginia (in the Shenandoah Valley). Field work is an option for Honors students on their individual research project.

November 2007

Callan examines a bentonite (ancient volcanic ash) layer in limestone beds south of Strasburg, Virginia (in the Shenandoah Valley).

November 2007

NOVA geology Honors student Anastassia Bogosian-Scissors demonstrates the orientation of a conjugate pair of en echelon tension gash arrays in the Lincolnshire Formation limestone, south of Strasburg, Virginia (in the Shenandoah Valley). Yellow arrows show dominant compressional stress direction. Light blue arrows show extensional direction. Small white arrows show the relative shear that produced the tension gash arrays.

November 2007

NOVA geology Honors students Anastassia Bogosian-Scissors and Victoria Martin point out the contact between two limestones: the more massively-bedded New Market Formation below, and the more finely-bedded Lincolnshire Formation above. As with the several photos above, this location is south of Strasburg, Virginia (in the Shenandoah Valley).

November 2007

NOVA geology Honors student John Weidner points at large blocks of talus generated through rockfall-type mass wasting, in answer to the question "Why does the tree trunk have such a weird shape?" North end of the Massanutten Synclinorium, south of Waterlick, Virginia.

November 2007

NOVA geology Honors student Victoria Martin provides a sense of scale along a probable fault zone (outlined in white lines) in the Massanutten Formation quartzite (meta-sandstone). North end of the Massanutten Synclinorium, south of Waterlick, Virginia.

November 2007

NOVA geology Honors student Sara Aznan measures boulder dimensions alongside the Potomac River north of Chain Bridge, DC. Field work is an option for Honors students on their individual research project.

November 2007

NOVA geology Honors student Stephen Howe identifies the composition of a boulder in the Potomac River north of Chain Bridge, DC. The boulder study is Stephen's Honors project: He is establishing a baseline database of positional and orientation information on individual boulders within the Potomac's floodplain, so we can then go back to those same boulders after a flood and see if they have moved, and by how much.

November 2007

NOVA geology Honors students Sara Aznan and Stephen Howe measure the distance from a study boulder to a fixed reference point. North of Chain Bridge, DC, in the Potomac River watershed.

November 2007

On the fall field trip of the Geological Society of Washington, NOVA instructors and students joined USGS geologists and representatives from the geology departments of area universities and industries to examine the Chilhowee Group sedimentary rocks of northern Shenandoah National Park, Virginia.

Photograph by Victoria Martin.

October 2007

Callan describes the volcanic breccia of the Catoctin Formation on the Shenandoah National Park field trip. This epidotized breccia can be seen on the north end of the Franklin Cliffs Overlook along Skyline Drive.

Photograph by Lee Austin.

September 2007

Another beautiful chunk of the epidote-green metamorphosed volcanic breccia of the Catoctin Formation, as seen on the Shenandoah National Park field trip. This sample was a piece of "float" from along the Limberlost Trail.

Photograph by Lee Austin.

September 2007

Student David Dantzler and Callan examine a sample. Snowball Earth field trip.

Photograph by Kevin Mattingly.

June 2007

The students on the Snowball Earth field trip examine an outcrop of "cap carbonate" on Goose Creek.

Photograph by Kevin Mattingly.

June 2007

Student Dennis Freeman takes a close look at the outcrop. Snowball Earth field trip.

Photograph by Kevin Mattingly.

June 2007

Student David Dantzler uses his hand lens for a close look at the rock. Snowball Earth field trip.

Photograph by Kevin Mattingly.

June 2007

Students Dennis Freeman and Sam Kelleher inspect a rock sample on the Snowball Earth field trip.

Photograph by Kevin Mattingly.

June 2007

Instructor Melissa Batum (NOVA Geology, Loudon campus) checks for specific types of rock in Goose Creek's gravel deposits on the Snowball Earth field trip.

Photograph by Kevin Mattingly.

June 2007

The Snowball Earth class poses in Goose Creek.

Photograph by Kevin Mattingly.

June 2007

Students Alison Krahn and Staci Scott take pH measurements of several streams in Prince William Forest Park on a Field Studies in Geology one-day field course. Quantico Creek, which drains the area of the Cabin Branch Pyrite Mine, has a lower pH than the South Fork, which does not have any mines in its watershed.

June 2007

Student Matt Beere cradles a huge clast (boulder) caught up in lava flows of the Chopawamsic volcanic arc (metamorphosed basalt is the green rock that wraps around the clast). Prince William Forest Park field course.

June 2007

Students on the Prince William Forest Park field course listen to ranger Laura Cohen, who explains the history of the Cabin Branch Pyrite Mine site (hill in background) and its subsequent reclamation.

June 2007

After being heavily promoted by Cultural Tourism DC (in the Washington Post and on WAMU's "Metro Connection"), Callan's Walkingtown, DC tour was attended by hundreds of interested Washingtonians. The peak attendance was somewhere above 250. Here, on Harvard Street NW, we discuss the deposition of sediments on the floor of the ancient Iapetus Ocean.

Photograph by Mara Cherkasky.

April 2007

Another shot of Callan's Walkingtown, DC tour "History before History: the Geologic Story of Washington, DC." Here, in the Zoo, we talk about Appalachian mountain building.

Photograph by Mara Cherkasky.

April 2007

An innovative new field technique: powerwashing dirty outcrops! Jay Kaufman (UMD) and his undergraduate student Tommy let Callan come along to help scrub clean some outcrops showing the contact between "Snowball Earth" cap carbonates and the overlying lava flows of the Catoctin Formation. The power washer was heavy, and we had to haul it across a waist-deep river and then through the forest to get to the rocks. The result was pretty great - but we won't publish it online until Jay has had a chance to publish it "on the cover of Science!"

Photo by Jay Kaufman.

April 2007

Physical Geology students (including three Honors students) smile because they are so thrilled to discover a real pothole (foreground) in the metamorphic rocks along the Billy Goat Trail, C&O Canal National Historical Park. The Potomac River's Mather Gorge is in the background.

April 2007

April 2007

Historian Eddie Becker (L) and Callan (R) meet with Uncle Beasley, the celebrated Smithsonian Triceratops. Uncle Beasley used to stand on the National Mall, in front of the Natural History Museum. Due to kids climbing on him, however, he was moved to the National Zoo. For a while, Beasley dwelt with the elephants and rhinos, but apparently he was relocated after spooking the pachyderms. Now he's hidden away, far from public view, next to the Henry Holt House (background).

January 2007

Aaron Martin (UMD), Victor Zabielski (NOVA), and Jay Delanoy (then NOVA, now GMU) cross Goose Creek en route to an exposure of Snowball Earth sedimentary rocks, near Aldie, Virginia.

December 2006

After a GMU-NOVA caving trip to West Virginia, GeoClub member Misha Samsonov demonstrates the orientation(s) of the bedding plane on two limbs of a fold. The axial plane of the fold runs from lower left to upper right. Fold is part of a monocline exposed along the north side of Route 55 in West Virginia. The sediments are deltaic deposits shed off the late Ordovician Taconian Orogeny. The sediments were then folded in the late Pennsylvanian Alleghenian Orogeny.

November 2006

Historical Geology students examine an exposure of the 464-Ma Kensington Tonalite (a Taconian felsic intrusive) along Broad Branch, Washington, DC.
November 2006

Historical Geology students return to the vans after examining D.C. rock outcrops along the Potomac River at Chain Bridge.

November 2006

Physical Geology students enjoy the view at a snack break overlooking Mather Gorge.

November 2006

Physical Geology students hike along the Billy Goat Trail. Here, they examine meta-greywacke, amphibolite, and migmatite rocks, and examine the down-cutting processes of the Potomac River.

October 2006

At Great Falls Park, Virginia, a group of Physical Geology students walking from the falls overlook (and flood crest markers) towards Glade Hill and the ancient bottom of the Potomac River.

March 2006

At Great Falls Park, Virginia, Physical Geology students show their geological prowess by correctly identifying the location of dozens of potholes drilled in the meta-greywacke bedrock by the Potomac River. Three large potholes are visible in this picture, all inclined downwards in an upstream direction.

March 2006

Historical Geology students admire a petrified cypress stump on display at Rock Creek Park Nature Center's visitor center, near Miliary Road, NW, in Washington, DC.

March 2006

Historical Geology students carefully pick their way over the rocks in Broad Branch, NW, en route to examine kink bands in the meta-greywacke of the Rock Creek Shear Zone.

March 2006

Historical Geology students hike along Broad Branch Road NW from a streamside exposure of kink bands in meta-graywacke towards a waterfall over the Kensington Tonalite. Boulders of Kensington Tonalite parallel the class's exceptional single-file line.

March 2006

Historical Geology students return to the vans after surveying incredible exposures of meta-graywacke along the Potomac River, just north of Chain Bridge, in DC's westernmost corner. These rocks were originally deposited in an ocean basin on an active continental margin, and were later metamorphosed during the Taconian Orogeny.

March 2006

Field Studies In Geology students examine the meta-graywacke exposed at Chain Bridge on a rainy fall day.

October 2005

A group of geologists and park rangers at a "Geologic Interpretation" workshop for Central Appalachian national parks, hosted by Harpers Ferry National Park, in Harpers Ferry, West Virginia. Callan Bentley is in the back row, wearing a black hat, towards the right. In the background is the Shenandoah River, about a quarter-mile upstream from its confluence with the Potomac.

March 2006

Callan (coffee in hand) gestures upstream from an exposure of meta-greywacke on the banks of the Potomac River, upstream from Chain Bridge.

Camera-phone photograph by Manu Malhotra.

March 2006

Describing an unlithified deposit of Cretaceous river gravels which lie on top of an unconformity surface in northwest Washington, DC. Note the roundness of the cobbles at the lower left, indicating that they have been transported a significant distance.

Camera-phone photograph by Manu Malhotra.

March 2006

Stunning outcrop of the Kensington Tonalite, a mid-Ordovician felsic intrusion associated with the Taconian Orogeny. This outcrop is in Broad Branch, upstream from the kink band locality shown below.

Camera-phone photograph by Manu Malhotra.

March 2006

Examining kink banding in meta-greywacke, Broad Branch, Rock Creek Park, Washington, DC. These kink bands overprint the regional foliation that developed during the Taconian Orogeny, and therefore represent a second generation of deformation of these rocks, at least locally. Also present at this locality are boulders and cobbles of the Kensington Tonalite, sitting in the stream bed, and therefore indicating a source area further upstream (see previous photograph).

Camera-phone photograph by Manu Malhotra.

March 2006