Virginia Rocks

Old Rag Mountain

By Dick Hall-Sizemore

It is time to take a break and talk about something entirely different related to Virginia — how the current physical structure of the Commonwealth in the 21st century came to be.

I have been taking an introductory geology course this fall from J. Sargeant Reynolds Community College. (Virtual, of course.)  I became fascinated with geology many years ago and determined to take a course when I retired and had the time. My class project was a short paper and presentation on the geology of Shenandoah National Park.

So, to give your mind some relief from constantly checking your computer for any updates on the ongoing ballot counting in other states, here are some of the things I have learned about our mountains:

  • For those Western snobs who dismiss the “small” Blue Ridge Mountains in favor of the “majestic” and “awesome” Rocky Mountains, there is this: By the time the Rockies were born or formed, the Blue Ridge had been born twice, weathering and eroding to sea level between “births”, and was well on its way toward its second weathering.
  • The oldest rocks in Shenandoah National Park are 1.1 to 1.2 billion years old.
  • The Blue Ridge, or more accurately, the Appalachians, of which the Blue Ridge is a part, were formed during the assembling of the ancient supercontinent Rodinia about 1.3 billion years ago. (Some geologists locate Rodinia around the South Pole.)
  • The mountains formed during this event are thought to have been as high as the Himalayas.
  • Deep in the earth beneath these mountains, was “basement rock” of granite and metamorphic rocks that later became part of the Appalachians, including Shenandoah National Park.
  • When Rodinia began breaking up, about 400 million years later, those mountains had weathered and eroded to sea level, but the basement rock was still there.
  • The breaking up of Rodinia was accompanied by a great outpouring of lava over the course of several million years. This lava, once cooled, was several hundred feet thick in places and covered Maryland, part of Pennsylvania, and the northern part of what is now Virginia.
  • There followed a series of seas and oceans that deposited large amounts of sediment on top of the lava fields.
  • Then there came a collision with another continental plate (the northern part of Africa) during the assemblage of another supercontinent (Panagea), about 300 million years ago.
  • At the time of this collision, the granite, basalt (cooled lava), and sedimentary rocks formed from the accumulated sediment, were under what is now Richmond and further east. The pressure generated by the collision pushed those accumulations both west and up to their current locations.
  • The mountains resulting from this collision (orogeny) are thought to have been as high as the Alps or perhaps the Himalayas. Over the past 200 million years, they have weathered and eroded to their current height.
  • Unrelated to the formation of Shenandoah National Park, but interesting nevertheless, the Richmond region sits on a large formation of granite, called Petersburg granite, formed about 350-380 million years ago.
  • In comparison, the Rocky Mountains are only about 80 million years old.

So, the next time you are hiking on Old Rag Mountain, realize that the rock around you is 1.1 billion years old.  Sort of puts today’s current events into a different perspective.

For anyone, who wants to delve into this deeper, here are a couple of good websites (the information at the JMU site is more detailed):

http://csmgeo.csm.jmu.edu/geollab/vageol/vahist/

Virginia’s Geologic History

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58 responses to “Virginia Rocks

  1. Very cool information.

    So, if I understand you correctly, Virginia’s mountains are very much like Virginia itself. Once upon a time, they were spectacular. Today, they are old and worn but genteel.

  2. The only thing that makes the Rockies look more impressive is the existence of a tree line. That, and at 9,000+ feet up, one beer will do ya.

    • You can simulate the effect of a “tree line” by visiting/hiking Buffalo Mountain in Floyd County. It’s peak elevation is a little under 4,000 feet, though, so you’ll need more than one beer.

      There are no trees on the summit of Buffalo Mountain and it really does resemble a buffalo in profile when viewed from a distance. I lived within a few miles of it for a year or so a long time ago.

      And yes, I know it is not in Shenandoah National Park, but it is in the Appalachians.

      • I’ve got to get up to the mountains more often. Hell, I’ll take the whole 6-pack. No problem. I usually pack the wife’s backpack too, so I ain’t carrying it. I was 40 years ahead of the TSA when it comes to packing ones own kit.

        The one thing Dick didn’t say in contrasting the Appalachians to the Rockies is that you can get over the Appalachians in a LeCar. Careful though on the downside. First thing to go is LeBrakes.

        • Reminds me of the time I was going downhill on US33 and smelling the brakes of the Ford Explorer in front of me. Apparently the driver didn’t understand what “2” or “L”, whatever it is on that vehicle, is for.

          It’s real fun to drive a Chevy Volt down one of those hills…the estimated range just keeps going up and up.

  3. Very good Dick! Yes, Geography, Geology, Geomorphology and related are fascinating! Add some rivers to that mix and I never tire of learning.

    Everywhere we go when camping and vacationing out west and in the East and on rivers – is ever cool!

    If you haven already, check Stream Piracy and Wind Gaps.

    and thank you for sharing!

  4. Great story! Too bad they won’t let dogs there. She would l0ve it.

  5. Thank you for explaining the old, worn but genteel nature of the Blue Ridge and Alleghenies. Yes, matches up very well with the present condition of those of us who used to love to day-hike through those forested glades.

    But back to geology. Dick, here’s something I hope you discovered the answer to. Along those hikes, at least through the Piedmont, one comes across lots of gnarly, white, crystalline boulders, often football sized or so, which I’d venture to guess were once pockets or inclusions in long-eroded metamorphic rocks brought to the surface by that Pangaea-era collision with Africa you mention. There must be a name and an explanation for these; they are a hallmark of Piedmont stream valleys, but absent from the sedimentary provinces east of the Fall Line or west of the Blue Ridge.

    And while we’re on the subject of geology, but of a more recent kind, during the Ice Ages, did your course touch on the drowned river valleys and former beach lines that meander through eastern Virginia? These, that record those periodic incursions and withdrawals of the sea over the recent past, measured in tens of thousands of years rather than tens of millions, still demarked by the high bluffs and flat floodplains and silted channels of the Tidewater rivers? Sea levels plainly rise and fall, and the land subsides and rebounds from the weight of glaciers; the seashore has risen and fallen in Virginia some 300 feet in both directions over that brief (geological) timeframe. Always natural causes — until now. Can we tell the difference, or make anything of the difference, or influence the result?

    I would enjoy such a course. Thanks for making us aware that it’s available.

    • It is a basic introductory course, so we have not gotten into the sort of detail about Virginia geology that you mention. That is one reason I chose Shenandoah National Park for my project: so I could learn something about the geology of Virginia. As for the gnarly, white crystalline boulders, they may be quartzite, which is metamorphosed quartz sandstone. Years ago, in hiking in the southern end of SNP, I came across that rock. I did not find out what it is until this year.

      • Used to paddle rivers with a guy named Ollie… he was a geologist.. and river trips with him were the best – in part , because Ollie knew the answers! 😉

  6. James Wyatt Whitehead V

    Old Rag is a tough but fine hike. The rock scramble makes muscles sore that you never even knew you had before. I used to take the Briar Woods High School history club up there every year. I remember this one young lady had never been on a hike before. I ended up carrying her huge pink Coach purse to lighten her load. My 5th great grandparents cabin is now a shelter on the back side of the mountain. William and Lucy Weakley of Weakley’s Hollow.

    • I though a tougher hike up White Oak canyon and down Cedar Run… Tore me up for a week.

    • “Old Rag is a tough but fine hike. The rock scramble makes muscles sore that you never even knew you had before. I used to take the Briar Woods High School history club up there every year. I remember this one young lady had never been on a hike before.”

      True enough, and I respect you for it. But all things are relative. Arrive on a summer day beneath Old Rag, and there in the parking lot strip down, tie on your Nikes and hike up your nylon shorts, and then take off, power glide and pump up the stony trail up ever higher onto the ridge, until you stop briefly at the great flat stone over looking the Blue Ridges rippling westward, and then refreshed, you leap and dance upward and across the stone gaps, until finally you belly crawl briefly though the the tunnel then run ever faster and light up the trail leading through the high flat lands, to the bald gentle summit, before you dance down behind the mountain from stone to stone, until you circle back around the backside of the mountain to the parking lot, with a youngster you taught to climb far more serious peaks beating quick behind you step for step until overtaking you at long last, showing you that your days of dominance are numbered, physically at the least.

      Then do it again with your wife and kids, a cool down after the Himalayas, a wholly different experience from your earlier dance and high mountain climbs to the roof of the world, and then on Old Rag set of wholly different obligations, sacrifice, and skills, confronting a your wife and kids, a monumental task of a different sort. Then do Old Rag in the coldest day of winter, ten below, camping beneath shining cold hard stars at ten below in small notch atop the cliff over looking the black ranges stretching westward toward West Virginia, only next morning to move over summit and to descent slowly around and behind to the parking lot then go on to the Graves Mountain Lodge, thinking of your grandfather 14 generations back into time, this valley, this old ragged mountain, this valley, mountains, and place, is the most extraordinary part of Virginia, to my memory.

      • James Wyatt Whitehead V

        Thanks Mr. Reed that was wonderful. A special place in Virginia. The most popular and well known hike on the east coast. Winter is a special time on Old Rag. Best chance for solitude.

  7. Homo sapiens around, what, 200,000 years? Agriculture 8000 years. A blip….

  8. Shiny object ploy. Ignore post!

    • I was aware of the age of the Appalachians. Geology always has me contemplating our short and tempestuous existence on this planet, and then I turn to astronomy….

      • If you’ve not already read it, I highly highly recommend Timothy Ferris’ “Coming of Age in the Milky Way.” It’s a very good, very readable history of western astronomy and cosmology.

  9. Very interesting! Reminds me of a talk by a park ranger at the Grand Canyon. She reminded us that the Grand Canyon is only here on a temporary basis. We just won’t live that long.

  10. If you ever get the chance I highly recommend Natural Tunnel State Park out by Duffield.

  11. Whoa, Georgia
    Georgia
    No peace, no peace I find
    Just this old, sweet song
    Keeps Georgia on my mind

    I said just an old sweet song
    Keeps Georgia on my mind

    🤡

  12. So Dick, you took this course virtually and you said you did a report and presentation. Can I ask how you did your presentation?

    • The class is conducted via ZOOM. I don’t know about ZOOM platforms generally, but the one used by JSRCC has a “share screen” feature. The instructor authorized me to share my screen, I opened my Powerpoint presentation, clicked on “share screen” on my end and everyone could see my presentation. The ZOOM application also has a microphone feature whereby students can ask questions or make comments.

      • Thanks. That’s sorta what I thought. On a citizen committee I participate on – we use GoToMeeting and the meeting is 100% virtual and there are multiple presentations on the agenda given by different people from their homes. The default for the microphone is mute for all but the presenter but anyone can unmute to ask questions. Votes are taken by roll call and sometimes the chair starts off asking for who opposes and if no one does, than he proposes the measure passes unanimous unless he hears objections.

      • I’m going to assume you got an ‘A’.

        • The course is not over yet. Besides, I am not taking it for credit (I get to take it free that way), so I am not sure that I will get any grade.

  13. Mr. Sizemore, what a lovely read as one’s 1st early am venture into one’s email. I am fortunate enough to live west of the Blue Ridge and the SNP. Have been here 26 years. The landscape I can see facing east from my home is always breathtaking and ever changing. And there’s is simply nothing so grand as a full moon arising over the mountains any season. A walk up Brown’s Gap Road east of Grottoes is a relatively easier effort than the Old Rag trek described above, but along the way one can see beautiful rocks, water, ferns, wildflowers in spring, snowfall in winter, dappled shade anytime it’s sunny, and real quiet. Thank you so much for sharing. Born a Richmonder, I’ve made the Central Shenandoah Valley my home for over a quarter century now and continue to marvel at my good fortune to be able to live here.

  14. I wonder why we got no good wind (energy) resources up there, like the Appalachian range that stretches from Pa. down to West (by God) Virginia? Are we just to short in the foothills?

    • here you go: ” Giant turbines could soon be spinning atop a Botetourt County mountain, marking the state’s first use of onshore wind energy.

      A permit for the long-delayed wind farm was recently approved by the Virginia Department of Environmental Quality, according to Apex Clean Energy, which plans to build up to 22 turbines as tall as 680 feet on a remote ridgeline.

      “We are on track to start site preparation work this winter,” said Charlie Johnson, senior development manager for the company.

      When completed, Rocky Forge Wind will produce enough electricity to power up to 21,000 homes at peak capacity. The 75-megawatt facility will convert wind to electricity and sell it to Dominion Energy, which has a contract to provide renewable energy to Virginia’s state government.”

      https://fredericksburg.com/news/state-and-regional/final-permit-granted-for-first-onshore-wind-farm-in-virginia/article_843a06e6-99f7-5cf2-a7ba-3c60073967de.html?utm_campaign=snd-autopilot&utm_medium=social&utm_source=facebook_fredericksburg.com&fbclid=IwAR312sMzUOzrp5wIY1hlNhkTmi0AvZteiZ-JQJhtX37YgoXts_aed7iOnxY

      • But that’s small taters compared to the thousands of wind turbines up in Pa to WV…on the wind resources map our Blue mountain winds are less ideal …slower winds.

        • I agree. I don’t think we’ll see many on Skyline Drive or even the Blue Ridge Parkway but further west on the Allegheny Front.

          • James Wyatt Whitehead V

            West Virginia could look like Holland soon. That ridge near Elkins is a tall one. Perfect for a forest of windmills.

          • Those mountains are in “folds” and the interior folds are not seen from the valleys…

          • Yes James, West Virginia is blessed with energy resources of not just coal but more cost-effective on-shore wind and nat gas too. They should diversify from the coal as fast as they can.

          • Places like this can be further “reclaimed” by putting wind and solar on top:

            not like there are scenic impacts and if you look in the distance, the multiple folds of mountains actually preclude scenic impacts anyhow.

            We do not have to remove a single tree to do this, just reclaim what we have already destroyed.

    • Much of the Blue Ridge, including Shenandoah National Park is national forest (Jefferson and Washington). I don’t think wind turbines will be allowed there. In addition to the one in Botetourt, cited by Larry, there were plans some years ago to erect wind turbines in one of the western counties in the Alleghenies. I seem to remember either Bath or Highland County. I don’t think that project ever went forward.

  15. Hey, there is no mention of Noah’s Flood in your list of histories of our grand Blue Ridge. Did they not speculate on any changes that may have happened in this global deluge while speculating on the rest of the history of mountain ranges?

    • There were times when the whole of what is now North America was covered by oceans. That is where a lot of the sediment came from. It rained for 40 days to create Noah’s Flood. I can’t remember how much time passed before the waters supposedly went down, but I doubt it was long enough to have created the sediments for which there is ample evidence.

  16. Hey, all you naturalists, whaddya know about the living habits of grey tree frogs?

    This 4th of July I opened my outdoor grill and found a grey tree frog. Grabbed him up and stuck him in a potted plant next to the grill while burning the burgers and dogs.

    Over the summer, I used the grill a couple more times and before using it checked to make sure he wasn’t in the thing first, but sometimes he was there. Put him in jar while grilling. When the grill cooled, put him back.

    Just took the cover off the grill. There he was.

    How far do these suckers range?

  17. which one?

    • Cope’s

    • I don’t recall their names but there are two species of tree frogs found in Virginia and apparently the ONLY way to tell them apart is to:

      1)Measure the outdoor temperature
      2)Measure how fast they are chirping/croaking.

      One of the species chirps/croaks faster than the other at a given temperature.

      And it’s theorized that they were originally the same species but evolved separately due to geographical isolation.

    • “Our two native gray treefrogs are identical in appearance. In the field the only two ways to distinguish H. chrysoscelis from H. versicolor is by their call and in some cases geographic location.”

      https://www.virginiaherpetologicalsociety.com/amphibians/frogsandtoads/frogs_and_toads_of_virginia.htm

      • Based on the pictures above, a Cope’s, but apparently maybe not. Can’t tell about his chirps, while I do talk to him, he has yet to speak. He doesn’t seem to mind being handled. Like I said, if he’s there when I want to use the grill, I just pick him up and move him. Odd behavior since most animals I’ve encountered won’t just let you pick them up.

        • reptiles are cold-blooded and will seek out warm places and places protected by wind. Most frogs won’t let you handle them – they’re pretty sure if you do, you’re a predator getting ready to eat them.

          I’d bet more on rodents going after the grease… 😉

  18. here’s that bad old “open source” Wiki again:

    https://en.wikipedia.org/wiki/Cope%27s_gray_treefrog

    Cope’s gray treefrog freezes in the winter! It produces large amounts of glycerol. The glycerol is changed to glucose and then it is circulated through the frog’s cells. The glucose acts like a kind of antifreeze and prevents ice crystals from forming in the frog’s cells. If ice crystals formed in the cells, they would rip the cells apart and kill the frog. The rest of the water and blood in the frog’s body then freezes, and its heartbeat and breathing stop! When the temperature warms up, the treefrog “thaws out” and returns to the trees!

    nhpbs.org/wild/copesgraytreefrog.asp#:~:text=Cope’s%20gray%20treefrog%20finds%20its,flies%2C%20grasshoppers%2C%20and%20beetles.

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