What Lies Beneath: Karst and the Ozarks

Copyright Jill Henderson 2002 By Jill Henderson – Show Me Oz

Recently I was leafing through a bunch of old pictures that I had taken of our first Ozarks farm and the surrounding countryside.  I was admiring my favorite shots – those of deep rolling hills and meandering rivers and clear blue springs.  These are the things that speak so clearly to love of this place – the thing that keeps my feet from wandering too far away for too long.

And what really makes the Ozarks so incredible is the one thing that we all seem to take for granted – the rocks.

I think it is fair to say that it’s pretty hard to live here and miss the rocks.  They are everywhere – kind of like armadillos, but better.  They’re in our fields and pastures and gardens, and sometimes they are in the walls and foundations of our homes.  And sometimes it seems as if  they were put here just to torture our shovels and our backs and to crack the windshields of our cars.  The rocks, that is, not the armadillos – they are another story entirely.

I’m not going to deny that I have often repeated the sarcasm that goes, “If I could sell rocks by the pound, I’d be rich!”  Because although it’s a tired old joke,  it’s still tickles my funny bone.  And besides, I am rich!  Not because I made a fortune selling our rocks, but because I get to live among them.

You see, these rocks are the Ozarks.  They are literally the foundation for the incredible beauty all around us.  We can thank rocks for our brilliantly twisting hills and our famously cold rivers, and for the countless springs that feed them.  Without rocks, we wouldn’t have any gravelly river beds to sun ourselves on, or any knobs or balds from which to take in the grandeur of our hills.

Without rocks, we wouldn’t have any shut-ins or rapids or chilly swimming holes.  Nor would we have so many deep hollows, mysterious caves and eerie sinkholes to explore.  Rocks aren’t just pretty either, they help create environmental micro-niches around seeps, springs and rivers, inside caves and under boulders and rocky ledges in the forest where all manner of creatures and plants live – some of which are found nowhere else on earth.  The Ozarks are literally built upon a monument of rocks, and without them, the Ozarks would simply not exist.

Without going into a deep geological history of how all these rocks came to be, suffice it to say that the Ozarks were framed upon a vast plateau hemmed in by a few volcanic or tectonic ranges.  These would be the St. Francois Mountains and the Ouachita Mountains, respectively.  And in between these large mountains was a vast inland sea filled with warm, sediment rich waters teeming with shellfish and coral reefs.

Over millions of years the entire area was submerged, uplifted and submerged again. The retreating waters carved entrenchments across the landscape and slowly ground the peaks down into the smooth, rounded shapes we see today.  The repeated inundations of the sea also laid down thick sediments that would eventually become vast layers of dolomite, limestone, sandstone, chert and shale.

As I wrote in my book, A Journey of Seasons, the predominant rock formations of the Ozarks are limestone, a brittle sedimentary rock composed of a type of calcium carbonate known as calcite. The most common limestone is dolomite, which is made up of calcium and magnesium carbonate with inclusions of chert and clay.

During periods of uplift, these deep limestone layers were fractured into massive square blocks and long horizontal plates.  The fractured stone of the cliff face in this image of Greer Spring is quite obvious.  2006 Alton MO (13) Greer Spring - branch below main spring

And as you might imagine, those fractures are perfect conduits for surface water such as rain or run-off from our city streets.  But before the water gets that far it is usually filtered through thick layers of decomposing mast, such as leaves, pine needles and grass.  And as it does, carbonic acid is dissolved into the water and carried down into the earth.

Now the acidified water continues its journey downward, making its way through the vast network of cracks and fissures in the limestone, slowly dissolving the calcite while leaving the harder materials intact.  Over millions of years, this corrosive action has engraved vast and complex networks of tunnels, underground rivers and caves beneath the surface of the earth. This type of geology is known as karst and it is the most distinguishing geologic feature of the Ozarks.

We will continue our conversation on karst in future articles, but until that time go outside and take a good look around the place where you live.  Pick up a few rocks and examine their shapes, textures and colors.  Get to know them better.  Look for the fossilized remains of that long ago sea or go down to the river and look into the cold, clear water that we are so blessed to have in our lives.

And wonder what you can do to protect it.

Watch Karst in the Ozarks, an excellent 18 minute documentary written and produced by Denise Vaughn and filmed and edited by Neil and Deanna Rosenbaum.  Follow the same link to find a creative and educational curriculum for teaching young people about karst topography.

 AJOS-214x3281.jpgA Journey of Seasons A Year in the Ozarks High Country

Set in the rugged heart of the Ozark mountains, A Journey of Seasons is memoir, back-to-the-land handbook and nature guide rolled into one.  Henderson’s 20-years of living off the land and foraging in the wilderness shines in this cyclopedic work filled with nature notes, botanical musings, back-woods wisdom and just a pinch of “hillbilly” humor.  This is one journey you don’t want to miss.

Available in the Show Me Oz Bookstore

Jill Henderson is an artist, author, and the editor of Show Me Oz . Her books, The Healing Power of Kitchen Herbs, The Garden Seed Saving Guide and A Journey of Seasons can be found in the Show Me Oz Bookstore. Jill’s work has also appeared in The Permaculture Activist, The Essential Herbal, Acres USA, and Llewellyn’s Herbal Almanac.

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4 responses to “What Lies Beneath: Karst and the Ozarks

  1. Hey Jill, nice piece. One of my favorite moments of life in the Ozarks is sitting on a gravel bar midfloat and picking through the rocks.
    For anyone wanting to go deeper into the geologic history of the Ozarks, watersheds.org has a timeline based on the geologic time scale you might have learned about reading National Geographic. This one is has additional text written by Verl Smith, retired Ava High School geology teacher, that tells you eon by eon, what was happening in the Ozarks. Just click on the links in the right hand column.http://www.watersheds.org/earth/gtime.htm

  2. Hi Lois, glad you liked it. I’m like you, I love rocks! Can’t hardly walk down a gravel road and look at anything else!! And thank you for the nod on the geologic time scale by Verl! I think watersheds.org is a great educational site!

  3. Pingback: Nature Notes: Sinkholes and Springs in the Ozarks | Show Me Oz

  4. Pingback: Happy New Year & Thank You…for Everything! | Show Me Oz

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