What Is That Gunk on My Rock?

Figure One - Side B of a 4.1-inch-long discoidal biface made from Alibates agatized dolomite. 
Pedogenic carbonate dominates this side, indicating this was the "down" position in the soil. 

For those of you who do not know the inspiration for my prehistoric adventure book series, the SHADOWS ON THE TRAIL Hexalogy, this is the story. It all began on an early summer morning in 2010 on a northern Colorado ranch. I discovered a prehistoric stone tool made from a red and gray striped rock created in a well-known prehistoric rock quarry in the Panhandle of Texas (figures one and two). After studying the flaking patterns on the artifact and based on other Paleoindian artifacts I found on that site, I concluded that it most likely came from the mysterious Folsom Complex around 12,600 years ago, give or take a century or two. 

Figure Two. Side A of the 4.1-inch-long discoidal biface. Side A is not showing as much pedogenic carbonate as Side B. Side A was the original side "up" in the ground.  

When I found that prehistoric stone tool, I recognized the distinctive rock type at once, and I knew the rock's source was Texas. So, what was Alibates agatized dolomite doing in northern Colorado? My mind wandered about the ancient people who made the stone tool and how it ended up on a Paleoindian campsite in northern Colorado, some five hundred miles away from the famous prehistoric rock quarry.  Who made the stone tool, and what was he or she like? What happened on that long journey from Texas to northern Colorado some 12,600 years ago? Since it was impossible for me to ask the Paleoindians, I wrote my own version of the trip in the SHADOWS on the TRAIL Hexalogy. 

One thing is for sure, that discoidal biface rested in that soil for a long, long time. I was surprised that some lucky dog before me did not find it, or a cow or horse hoof did not smash it to pieces. And what was all that white gunk covering its surface? Inquiring minds wanted to know. 

                             Figure Three - Book One in the Series. CLICK to ORDER.

The white stuff is called pedogenic (secondary) carbonate, and it is mostly CaCO₃ or calcium carbonate. How does pedogenic carbonate end up on artifacts, rocks, and geological features? I am glad you asked. Pedogenic carbonation occurs when rainwater mixes with carbon dioxide in the atmosphere. Together, they form a diluted carbonic acid or H₂CO₃ in the soil. That weak acidic mixture dissolves other minerals in the soil and yields water-soluble calcium carbonate, bicarbonate, and other salts capable of precipitating onto other rocks and minerals when groundwater conditions permit it. 

Figures four and five are photographs of a Paleoindian ultrathin knife form where pedogenic carbonate completely took over one side of the artifact. The Paleoindian who made that knife form used obsidian as the raw material. In figure four, Side B is almost completely covered with pedogenic carbonate. 

            Figure Four - Side B of a 6.5-inch-long ultrathin knife form showing extensive pedogenic carbonate, indicating that side was "stratigraphically down" in the soil. 

John Bradford Branney Collection.  

Pedogenic carbonate obviously detracts from the artifact's original beauty and has limited my ability to study the flaking patterns on Side B. I can only guess what the flaking looks like underneath the gunk that covers it. The only good thing about pedogenic carbonate is that it eliminates any doubt as to the authenticity of the artifact. As far as I know, artifact replicators and fakers have not figured out how to fake pedogenic carbonate, but I am sure they are trying their best. 

Figure Five - Side A of a 6.5-inch-long ultrathin knife form showing no or little pedogenic carbonate. Side A was "stratigraphic up" in the soil. John Bradford Branney Collection.  

A geopetal indicator is any rock feature that demonstrates the relationship of top to bottom at the time of formation or placement of the rock. An example of a geopetal indicator in the geology world is the orientation of cross-bedding in a fluvial deposit. In the archaeology world, pedogenic carbonate lets us determine up or down for an artifact, bone, or feature.  

Pedogenic carbonate accumulates on or between sediment grains in the soil, occluding and cementing the sediment. Pedogenic carbonate forms a geopetal structure that first accumulates on the lowest part of its host. In the case of a buried prehistoric artifact, pedogenic carbonate coats the lowest portion of the artifact first. When found, the presence of pedogenic carbonate establishes the "stratigraphic up" position for that artifact. Figure five shows the "stratigraphic up" for that ultrathin knife form. 

Where will pedogenic carbonate most likely occur? Low rainfall is the single most important factor for developing pedogenic carbonate. Low rainfall allows the formation of pedogenic carbonate deposits near the surface of the ground, while heavy rainfall flushes the water-soluble salts down into the groundwater table, removing them from the sediments where we oftentimes find prehistoric artifacts.

How long does pedogenic carbonate take to affect a prehistoric artifact? That all depends on the soil and the rainfall conditions. I have Late Prehistoric artifacts that have the beginnings of pedogenic carbonate, while some of my Paleoindian artifacts show no sign of pedogenic carbonate.  

Figure Six - 3.8-inch-long Clovis spearpoint completely blanketed in pedogenic carbonate on
both sides. Surface found on private land in the high desert of northern New Mexico.
The original host material is unknown. John Bradford Branney Collection.      

I have read comments from people on social media sites asking for advice on how to remove pedogenic carbonate from artifacts. Most knowledgeable collectors will reply something like, "Leave the artifact alone." Occasionally, you will find someone who believes they are smarter than Mother Nature, and he or she recommends some concoction to remove the natural deposit. As far as I know, no one has ever been successful in removing pedogenic carbonate without damaging the artifact. Pedogenic carbonate chemically bonds to the soil, sediment, and rocks. It may look like it is only a surface coating, but it is chemically bound to the crystal lattice of the rock. 

What's my bottom line? Leave pedogenic carbonate alone! If you cannot learn to love the pedogenic carbonate on your artifacts, at least respect it! Like a good marriage, pedogenic carbonate is with your artifact forever.  

  

Reflections...

I found my first "perfect arrow point" when I was nine years old in good ole Wyoming. At the time, I was playing third base on a Little League baseball team called the Merchants. I looked down at the ground between second and third bases, and there was a jasper arrow point lying at my feet. Even at the ripe old age of nine, I was hooked on artifacts. Actually, I was hooked on artifacts much earlier than even nine years old. My mother inherited her father's extensive artifact collection, and from age six on up, I was fascinated with those artifacts. That was six decades ago, and my fascination with Prehistoric America has never left me.  

If you get a chance, read my prehistoric adventure series titled SHADOWS on the TRAIL Hexalogy. I think you will enjoy the book series. The adventures will transport you to a happy place, thousands of years in the past.         

 

A Stone Cold Inspiration - SHADOWS on the TRAIL Hexalogy

Figure One - Alibates agatized dolomite discoidal biface found by the author on a ranch in northern Colorado in 2010. The type of flaking and its association with four 

Folsom artifacts lead the author to believe this discoidal biface was

associated with the Folsom Complex.

The 4.1-inch-long discoidal biface above was my inspiration for the prehistoric fiction novels in the Shadows on the Trail Hexalogy. The prehistoric hunter who made this discoidal biface used it as an all-purpose tool for scraping animal hides, chopping wood, and cutting through animal bone and tendons. In addition, the prehistoric nomad who carried it also used the discoidal biface as a portable rock supply. When they needed a new stone tool or projectile point, they simply hammered off a flake and made a new tool, right there on the spot.

Figure Two - Was the discoidal
biface on its way to becoming
an ultrathin knife form? 

I found the discoidal biface in northern Colorado on a site where I have documented prehistoric artifacts dating back at least 13,000 years. There was something else interesting about the artifact. The prehistoric nomad made the discoidal biface from Alibates agatized dolomite, a rock type originating from the Panhandle of Texas, some five hundred miles to the south. That led me to believe that the nomad made the discoidal biface in Texas and transported it by foot to northern Colorado, where he lost or misplaced it.

Finding Alibates in northern Colorado is not common. That was the first discoidal biface I had ever found made from that rock type. Why did that prehistoric human carry that large piece of Alibates agatized dolomite all the way from Texas when there were numerous sources of rock within a stone’s throw (pardon the pun) of where I found the artifact? It appears that prehistoric humans were enamored with the beauty of Alibates agatized dolomite, and I can see why. Alibates artifacts are found far and wide from their Texas source. Prehistoric humans either carried the rock from Texas or traded it with other prehistoric humans.       

For those readers unfamiliar with Alibates, it is a very distinctive, multicolored rock with colors ranging from maroon to red and gray to black. Mix in some white and tan with banded shades of pink, blue, purple, and brown, and Alibates exhibits a rainbow of colors. It is apparent that prehistoric people were fascinated with its bright and exotic colors and must have believed that the rock held some mystical power over the animals they hunted. Prehistoric people made some of the finest prehistoric artifacts in existence from Alibates agatized dolomite.     

Figure Three - Side B of the discoidal biface. 
Note the pedogenic (secondary)
carbonate that formed on the artifact.   

Of the thousands of artifacts that I have found, few captivate my imagination like this particular discoidal biface. I do not know why; it is just special to me. When I found that ancient discoidal biface from Texas, my mind went into overdrive thinking about who made it, what he or she was like, and how it ended up in northern Colorado.

The SHADOWS on the TRAIL Hexalogy is my six-book series about the people who made that particular artifact, and its journey to northern Colorado, so that I could find it 12,000 years later. 

The SHADOWS on the TRAIL Hexalogy is the prehistoric adventure that defines all other prehistoric adventures! A small band of Paleoindians fights to survive in a violent and unpredictable world over 12,000 years ago. The late Pleistocene is a time of dramatic climate change, large megafauna extinctions, and the shaky alliances amongst numerous bands of humans surviving at the time. 

Figure Four - The second edition of the SHADOWS on the TRAIL. 

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   SHADOWS on the TRAIL at better booksellers everywhere.     

                                                  

The Shadows on the Trail Trilogy IS a Matter of Survival!!

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First, a brief update on the status of the Shadows on the Trail Trilogy. All three books are now out! I am working on the fourth book. There is no reason not to add Shadows on the Trail, Ghosts of the Heart, and Winds of Eden to your book list and get ready for the fourth book. You can visit Texas and Colorado about 10,700 years ago without leaving your living room!

For those of you who have already read the Shadows on the Trail Trilogy, I thank you and I appreciate the notes and comments you have sent me in regards to the books. I promise you that the fourth book will not let you down! Now, on with the show!

Figure two - The trappings of modern society. Piled
up luggage at some airport, not a rare occurrence.  

Have you ever noticed how modern-day society has surrounded itself with physical possessions and how many people have become prisoners to their possessions? What would any of us do without the conveniences that surround us? When we are hungry, we go to the refrigerator or a restaurant. When we are bored we watch one of four hundred channels on our high definition plasma televisions. If we want music, we can listen to one of thousands of songs on our iPods or smart phones  The possessions and trappings go on and on. We have become a society that is completely dependent on our modern conveniences. We are spoiled!  
     

To illustrate my point, I am going to cite a recent example from my personal life and compare it to the lives of the Folsom People, the protagonists in the Shadows on the Trail Trilogy. Recently, my wife and I took a four-day trip to California and when we arrived at the airport we each had a suitcase. In addition, I had a stuffed backpack with my laptop, books, and various other electronic gadgetry and essentials. My wife had a laptop roller suitcase with all of her gear. Four days, four suitcases! When we finally boarded the airplane (another amazing transportation convenience), the passengers fought to get their precious possessions stowed in the limited overhead luggage space. I looked around and watched people shoving everything but the kitchen sink into the overhead luggage bins. It gave me pause to reflect about our heroes in the Shadows on the Trail Trilogy, Chayton and the Folsom People.     

Figure three - Dinner time, literally fast food!

Let’s jump into our time machine called the Shadows on the Trail and go back to around 10,700 years ago, the days of Chayton and the Folsom People. They did not have any of the modern conveniences we have today. They couldn't go to a grocery store or a fast food restaurant if they were hungry. If they needed to travel from Point A to B, they did so by walking, there were no cars, buses, planes, or even horses. The Folsom People had to carry everything they owned when they roamed from place to place. All of their possessions were transported by them and their wolf dogs.

                

Below is a passage from the first book of the Shadows on the Trail Trilogy where our hero Chayton was preparing a multi-day crossing of the inhospitable Arid Plains with two other hunters.  The passage describes what Chayton took with him on this difficult journey. He would have to survive an extremely hostile and unpredictable environment with very little. If he and the hunters were going to eat, they would have to find, kill, clean, and cook the food. If they became thirsty, they would have to find water. There were no maps or convenience stores. They would have to hunker down near the safety of their campfire during the night and have to deal with the scorching heat of the Arid Plains during the day.

          Chayton carried a deerskin quiver with five spears on his back and his spear thrower on his left hip. On his right hip, he carried his water pouch and on his back, he carried a hide pouch containing the four remaining inyan wakan or sacred rocks, four spear points, knife blades, a sandstone abrader, a hard wood spindle for fire starting, and several chokecherry patties. On a leather strap around his neck, Chayton carried a stone knife with a handle made from a shortened bison rib. In his hand, he carried a long spear that doubled as a walking staff. Except for a blanket and the hut he was leaving behind, this was all Chayton owned in the world. 

Figure Four - Folsom artifacts from the Author's Collection.

                                                                
            Figure four is a photograph of the stone tools that Chayton might have carried in his deerskin pouch. In the center of the photo, notice the red and gray banded discoidal biface he brought on the journey from his original canyon home in future Texas. To the right of  the discoidal biface are two razor-sharp ultrathin knives used for butchering animals and in the lower left hand corner, an end scraper used for hide work. Resting on top of the discoidal biface are two Folsom projectile points. Add to the hide pouch a tool to create fire and a small amount of dried food and Chayton could survive anywhere. How about you? I know I couldn't.  

Shadows on the Trail Trilogy is not only an action adventure series, it is a testament to human survival. Get your copy now and learn how Chayton and the Folsom People survived!    

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The Seed for the SHADOWS on the TRAIL Hexalogy

Figure One - Four-inch-long discoidal biface made from Alibates 

agatized dolomite surrounded by Folsom artifacts. 

John Bradford Branney Collection. 

The seed for the prehistoric adventure book series, the SHADOWS on the TRAIL Hexalogy, sprouted on a warm summer morning in 2010 on a beautiful ranch on the high plains of northern Colorado. Since I was a child, my passion has been searching for the artifacts of our prehistoric past. For over three decades, I hunted prehistoric artifacts on that Colorado ranch two or three times per year. The ranch sits in a large bowl-shaped valley surrounded by rolling prairie and sandstone bluffs. During prehistoric times, a natural spring supplied water to a stream that meandered down the length of the valley. The stream attracted large mammals, which in turn attracted prehistoric humans.

Over the years, I have found over a thousand prehistoric artifacts in this valley, many of them stone projectile points known as arrows, darts, knife forms, and/or spear points. From an archaeological perspective, we use stone projectile points as indicators of the prehistoric culture that left them behind. By tying a style and technology of a projectile point to a dated archaeological site, archaeologists established an age range for certain stone projectile point types. Even when I find one of those projectile point types on the surface of the ground, out of archaeological and stratigraphic context, I am pretty sure of the prehistoric culture it came from. Throughout North America's prehistory, humans have changed the style and technology of the stone projectile points they used, allowing us to earmark the style and technology to specific prehistoric cultures.

Figure Two - 1.2-inch-long Folsom dart point. 

Let's say I find on the high plains a thin, fluted projectile point with micro retouch along the blade edges like the artifact in Figure Two. I can be pretty sure it is a Folsom point and that the age is somewhere north of 12,000 years old.

Figure Three - BEYOND the CAMPFIRE, the fifth book
in the SHADOWS on the TRAIL Hexalogy. 

Back to that northern Colorado ranch...From the different types of projectile points I have found at the northern Colorado ranch, on what I now call the SHADOWS on the TRAIL site, I have a pretty clear understanding of the prehistory for that valley. Nomadic hunters and gatherers called Clovis came to the valley after the end of the last ice age, sometime around 13,150 years ago. After Clovis came other people and cultures who made different projectile point styles, right up through the historical Indian tribes in the 1800s. 

Figure Three - Four-inch-long discoidal biface made 

from Alibates agatized dolomite, a rock type originating 

at a prehistoric rock quarry in Texas.

John Bradford Branney Collection. 

        Back to that warm summer morning in 2010. I was strolling along in the sand of a dry streambed. My eagle eyes were watching the ground, searching as they always do for that sun-reflected glint of the kind of rock used by prehistoric humans. Out of my peripheral vision, I spotted a large piece of chert (a rock type used to make prehistoric tools) lying on a small pedestal of sand. I knew immediately it was a prehistoric artifact. Before picking the artifact up, I studied it from every angle. I pulled out my camera and took several photographs of the artifact the way I found it (unfortunately, every photograph turned out blurry). I finally picked the artifact up and brushed away centuries of accumulated dirt and sand. One side of the prehistoric artifact was encrusted with pedogenic carbonate deposits, an indicator of its antiquity. I smiled while studying the prehistoric artifact, knowing that I was probably the first human to touch it in over 12,000 years. Think about that; over TWELVE thousand years! That, my friends, is a very long time.

Archaeologists call the type of prehistoric artifact I found a discoidal biface or core, a technical name for a large and flat disc-shaped tool made by prehistoric humans for a specific purpose. The Paleoindian who made this discoidal biface hammered out a fairly sharp edge around the circumference of the rock. The prehistoric human probably used this artifact as an all-purpose tool for scraping hides, chopping wood, and cutting through animal bones and tendons.

Figure Four - Paleoindian. Photo courtesy 
of the Manhattan Museum.  

Besides being an all-purpose tool, the discoidal biface served another purpose. Since these nomadic prehistoric hunters were not always near a quarry or source of rock for tools, they used this large discoidal biface as a portable rock supply. When the Paleoindians needed a new stone tool or projectile point, they simply hammered off a small piece of rock from the discoidal biface and made a new tool, right there on the spot.

      The discoidal biface I found that day in northern Colorado was special for another reason. The prehistoric human who made it used Alibates agatized dolomite, a rock type only found on the Panhandle of Texas. That led me to believe that the Paleoindians who made this discoidal biface brought it five hundred miles north to Colorado, where they ultimately lost or abandoned it. Finding Alibates agatized dolomite in northern Colorado is not a common occurrence. Out of a thousand pieces of chipping debris that I pick up on an annual basis, I might find one or two chips made from Alibates. That was the very first discoidal biface I ever found made from Alibates agatized dolomite. 

My initial question when I found the discoidal biface was why a Paleoindian would carry that bulky piece of Alibates agatized dolomite all the way from Texas when there were numerous tool stone sources within a stone’s throw (literally) away from where I found that artifact? 

I believe one reason was that Paleoindians and other prehistoric humans were enamored with the beauty of Alibates agatized dolomite. Alibates agatized dolomite is a very distinctive rock type with colors ranging from maroon to red and gray to black. Mix in some white and tan with banded shades of pink, blue, purple, and brown, and Alibates agatized dolomite shows off a rainbow of colors. Prehistoric humans were fascinated with its brilliant and exotic colors and must have believed that the rock held some mystical power over the mammals they hunted. 

     

Figure Five - Folsom dart point made from Flattop 

Chalcedony and found near the discoidal biface.
John Bradford Branney Collection.   

When I found this ancient discoidal biface made from Texas rock, my mind wanted to know who made that artifact, what that person was like, and what happened to them. The SHADOWS on the TRAIL Hexalogy is my six-book series about three generations of Paleoindians who started a journey in Texas and ultimately ended up in northern Wyoming. During the journey, one of the Paleoindians dropped that discoidal biface on the ground, and twelve thousand plus years later, I found it. 

The main characters of the adventure belong to a real culture of prehistoric humans called the Folsom People, a mystical group of hunters and gatherers who roamed western North America for about five to seven hundred years from around 12,900 years ago to 12,200 years ago. The Folsom people left behind a distinctive calling card for us to discover: beautifully crafted stone projectile points that distinguished themselves with a wide flute or channel running most of the length of the projectile point from tip to base. Today, finding a Folsom projectile point on the prairie or plains is the equivalent of finding the Holy Grail. Folsom projectile points are as rare as hen's teeth, and they are arguably the finest made projectile points in North America’s prehistoric past. 

Join the adventure by reading the 

SHADOWS on the TRAIL Pentalogy

you will be glad you did!  

Figure Six - The discoidal biface is surrounded by four Folsom dart points and one 

Alibates end scraper at seven o'clock. The age for these artifacts is 

twelve thousand years plus. John Bradford Branney Collection.  

The historical fiction novels written by John Bradford Branney are known for their impeccable research and biting realism. In his latest blockbuster novel, CROWN of LIGHT, Branney launches his readers smack dab into the middle of the late Pleistocene along the high plains of North America. CROWN of LIGHT is Branney's fourteenth book.  

John Bradford Branney holds a geology degree from the University of Wyoming and an MBA from the University of Colorado.