The Blue Ridge: A Geological Autobiography
If the Blue Ridge could write its own long and complex history, surely it would chisel the words in stone. Fortunately, it did just that. And fortunately, we have a translator in our midst. During our January 2019 Geology Expedition, USGS Geologist Arthur Merschat unraveled the story of the geologic events that left Virginia’s oldest basement rocks exposed for us to access and admire.
If the Blue Ridge could write its own long and complex history, surely it would chisel the words in stone. Fortunately, it did just that. And fortunately, we have a translator in our midst. During our January 2019 Geology Expedition, USGS Geologist Dr. Arthur Merschat unraveled the story of the geologic events that left Virginia’s oldest basement rocks exposed for us to access and admire.
The Blue Ridge Mountains as we see them today are a result of several major geologic events. Initially, tectonic plates drifting together over time caused continental collisions during the Grenville orogeny and produced the supercontinent Rodinia around 1 billion years ago. Around 750 million years ago, Rodinia began to break up and caused a series of lava flows and volcanic eruptions. The final breakup resulted in the pulling apart of the continent and the formation of oceans, and for a time, Virginia existed as a tropical marine environment located south of the equator. Evidence of this can be seen in the fluvial to marine sedimentary rocks of the Chilhowie Group along Whitetop Rd. However, during the Alleghenian orogeny 300 million years ago, Africa collided with us to form the supercontinent Pangea. This event thrust billion-year-old basement rocks and 750 million-year-old volcanic rocks of Mount Rogers above the layered rocks of the Valley & Ridge. It is these ancient, metamorphosed rocks that we encountered on our trip.
Matrix-supported diamictite with hammer for scale.
The trip began with a visit to a road cut of 750 Ma diamictite (pictured) within the Konnarock Formation. This sedimentary rock consists of clasts (pieces of rock or minerals that range from pebbles to cobbles and boulders) supported by a matrix of sand and clay and tells us that this area was once a glacial environment.
Our next stop within the Konnarock Formation provided an opportunity to spot dropstones. During glacial melt, granite stones that had been carried in the ice dropped into the soft sediment (rhythmite and laminite) of the lake beds.
Next, we ventured north on Whitetop Rd. to view elements of the Unicoi Formation within the Chilhowie Group, where a 540 Ma basalt flow is easily visible within a road cut on Iron Mountain. From north to south it is possible to see the basalt flow with conglomerate, arkose, and shale below, and quartzite above. During metamorphism, vesicles - former gas bubbles within the volcanic rock (basalt) - were filled with other minerals such as potassium feldspar and calcite. These filled vesicles are referred to as amygdules (pictured).
In this chunk of basalt with potassium feldspar amgydules, Dr. Arthur Merschat tests for calcite using hydrochloric acid.
Black slate in the Hampton Formation.
Our next stop was the Hampton Formation at Skulls Gap on Whitetop Rd. Here, an underwater landslide occurred while the black shale (formed in an anoxic environment) and sandstones were deposited, which were later metamorphosed into slate and quartzite (pictured).
Heading across Whitetop Mountain and along the Stone Mountain Fault, several stops allowed us to view rocks within the Mount Rogers volcanic center, including flow-banded lava, arkose, and volcanic breccia, as well as greenstone featuring phenocrysts of plagioclase (large, conspicuous crystals of plagioclase feldspar), and more amygdules, this time filled by epidote and quartz. Next, we encountered the Buzzard Rock member, the lowest and oldest rhyolite in the Mount Rogers volcanic center at over 755 million years old.
Geologist Dr. Arthur Merschat describes the greenstone at Elk Garden.
Phenocrysts of plagioclase embedded in greenstone.
Potassium feldspar and plagioclase phenocrysts in the Buzzard Rock rhyolite.
Once we crossed over the Catface Fault into the Pond Mountain volcanic center, we encountered mylonite, a fine-grained fault rock containing muscovite which had been lineated due to shearing and flattening.
Mylonite with lineated muscovite along the Catface Fault.
Farther up the road, we glimpsed a peek at the 1.1 billion-year-old basement rocks within the Stone Mountain thrust sheet. These coarse, whitish-gray and pink granite rocks contain minerals that were crystalized deep in the earth’s crust before the formation of the Blue Ridge Mountains.
Our final stop at a road cut afforded us a wide view of the large clasts of rhyolite, granite, and arkose that comprise this boulder conglomerate. Beautiful!
Participants admiring a road cut of boulder conglomerate.
The Geology Expedition was a full-day adventure of traveling through and unraveling millions of years of the Blue Ridge’s history. And although we only encountered a fraction of what there is to see, we ultimately acquired a deeper understanding of the geologic events that created this montane region*, the very foundation of our Center.
*If you are interested in learning more about the natural history of this unique region, join us for the Spring Mt. Rogers Naturalist Rally May 10-12, 2019.
Members FREE, Non-members $10
Trip Photo Gallery
KTS Historic Photos
Recently we were gifted a treasure trove of over 500 historic photos of the old Konnarock Training School by Sheila (Blevins) Brown and the Blevins family. The three albums appear to have been compiled over the lifespan of the school, from 1924-1959, with photographs ranging from the construction of the facility to field trips up Whitetop Mountain to yearbook-style portraits.
Recently we were gifted a treasure trove of over 500 historic photos of the old Konnarock Training School by Sheila (Blevins) Brown and the Blevins family. Their family managed to keep this invaluable resource safe since the school closed in 1959, nearly 60 years ago. The three albums appear to have been compiled over the lifespan of the school, from 1924-1959, with photographs ranging from the construction of the facility to field trips up Whitetop Mountain to yearbook-style portraits. We here at Blue Ridge Discovery Center are very honored to have been entrusted with this resource.
Our first step has been to digitize the photographs, and we will be delivering copies to the Grayson County, Smyth County, and Washington County Historical Societies. In the long run, these photos will form the core of the historic interpretive displays about the property, but in the short term, we have created a page to view the photos on our website, which is listed below.
The full wealth of information in this archive has yet to be discovered. It will take the eyes of family members and the community to draw out the entire story. Please share this archive with friends and family so they can let us know more about these photos. Anyone with more information can contact us at info@blueridgediscoverycenter.org.
The timing of this gift could not be better. With the imminent restoration of the building, these historic photos are directly informing our design decisions. But beyond that, these photos are giving us an incredible insight into the landscape at that time. By observing the background carefully you will see landmarks, trees that where saplings then and a massive stump now, old roads and paths, outbuildings, pastures, and more. There are photos of a steam powered excavator, a basketball game in the 20’s, the old Roosevelt Farm, early girl scout activities, and Whitetop’s bad weather (ha!).
One of the greatest joys of scanning these at 600dpi and looking at them full-screen is realizing that when a photographer goes to take a photo, kids will be kids regardless of the era! Their fidgeting, their expressions, picking on one another, the poses, and their boundless smiles are timeless and tell all!
A Reunion of the Konnarock Training School Alumni
Blue Ridge Discovery Center and the Konnarock Retreat House hosted the alumni of the Historic Konnarock Training School and their families on July 7th, 2018. Since the 1960's this group has been getting together to share stories and pass down the oral history of the KTS.
Blue Ridge Discovery Center and the Konnarock Retreat House hosted the alumni of the historic Konnarock Training School and their families on July 7th, 2018. Since the 1960's this group has been getting together to share stories and pass down the oral history of the KTS.
The group has dwindled but the ones in attendance were no doubt as feisty as ever. Beyond the stories of polishing the dining room floor with the weight of their rumps being pulled around on a rug, of climbing out on the roof for fresh air, tending the school garden, of the inspiring Biology teacher Mrs Kirby, and riding the school truck to Whitetop. Beyond all of that. The most inspiring part of the event was the engagement of their children, grandchildren, and great-grandchildren. It is very clear that the impact of the Konnarock Training School has reverberated throughout the community for generations, affecting the trajectory of all sorts of families. It is a powerful idea, to build an educational institution, but often times it is difficult to see the broad-reaching impacts.
This weekend, we not only got to look into the past, but we also got to see our future, an insight into the potential impacts BRDC can have on individuals, families, and a community. It was heartwarming and inspiring and we can't wait to continue that legacy in Konnarock!
Mount Rogers Naturalist Rally History
We are excited to share the digital scans of the historic Mount Rogers Naturalist Rally Brochures. Thanks to the diligent efforts of Ruth and David Ross the entire collection of Rally Brochures is now available for digital reference. The documents cover every year dating back to 1981!! There is a wealth of knowledge and an impressive list of speakers in these documents. Browse through the files and share if you find anything fascinated buried in the text!
We are excited to share the digital scans of the historic Mount Rogers Naturalist Rally Brochures. Thanks to the diligent efforts of Ruth and David Ross the entire collection of Rally Brochures is now available for reference. The documents cover every year dating back to 1981! There is a wealth of knowledge and an impressive list of speakers in these documents.
CONSIDER SUPPORTING THE RALLY
The Mount Rogers Naturalist Rally is a grand tradition that dates back to 1974. Over the years it has gone through many changes but the root goal has stayed the same: to connect our community to one of the most spectacular landscapes on Earth. If you would like to see this tradition continue for the next generation please consider making a donation to support the Rally.
The Mt Rogers Naturalist Rally: Backyard Edition is off to a fantastic start! It is delightful to have so many participants in our iNaturalist project. We love seeing you getting outside to Explore, Discover, and Share with us.