F is for Flattop Chalcedony; S is For Shadows on the Trail!

Figure One. 1.8-inch-long Midland dart point I found on September 2, 1997, near Flattop Butte 
on private land in Logan County, Colorado. It was made from a pale red
Flattop chalcedony. The age is around 12,000 years plus, give or take.
John Bradford Branney Collection.  

 

Welcome to my series of articles on High Plains raw materials. In this article, I explore the raw material called Flattop chalcedony, aka Flat Top Chalcedony, Flat Top Chert, Flattop Chert, or simply FTC. Flattop chalcedony is the most abundant prehistoric tool stone found by collectors in northeastern Colorado. Anyone who hunts artifacts in northeastern Colorado, the panhandle of Nebraska, or southeastern Wyoming finds artifacts and/or chipping debris made from Flattop chalcedony. It is nearly impossible to avoid the material when artifact hunting in those areas, especially in northeastern Colorado. What is Flattop chalcedony and where is its geological source? I will explore that and much more in my article, but first I want to take you on a little journey back in time around 12,600 years in what we now call northeastern Colorado.    

 

CLICK for WINDS OF EDEN

I took the passage in blue from my prehistoric adventure book titled WINDS of EDEN, the third book in my prehistoric saga called the SHADOWS on the TRAIL Pentalogy. This particular book passage illustrates a Paleoindian tradition called flintknapping or the making of projectile points and stone tools from specific types of rock. In that particular scene, an elderly grandfather is teaching his grandchildren how to make stone spear tips, in that case, they were making what we now call Folsom points. Since there is no archaeological evidence that North American Paleoindians used any kind of written language, we must assume that they passed along their traditions and practices from generation to generation through "word of mouth" and/or "an apprenticeship for children".  

The old man motioned for his two young grandchildren to sit down in front of him, close enough to see, but far enough away to avoid flying pieces of sharp rock. The old man readjusted the flat rock with the tip of the spear point. He then carefully positioned the groove in the antler punch with the tiny knob at the base of the spear point. When everything was to his liking, the old man picked up the heavy antler hammer and took a couple of practice swings in the air. The old man then held the antler hammer above the antler punch and swung down with enough force to transfer energy from the antler punch through the rock. The rock popped loudly and when the old man lifted up the spear point for the children to see, a flute or groove ran longitudinally up the entire length of the spear point. The children laughed as if they just witnessed great magic. Their eyes were as big as the moon as they looked around at each other. The old man gazed around at the children, smiling. The old man was proud of the flute in the spear point and relieved that he could still do it. However, what made him the happiest was passing down the fluting tradition to the next generation of the tribe.

WINDS of EDEN and the rest of my books in the SHADOWS on the TRAIL Pentalogy mix in evidence from high plains archaeology while chronicling the lives and challenges of my fictional protagonists, the Folsom People. In the books, my heroes and heroines journey across what we now call Texas, Colorado, and Wyoming and encounter many challenges that test both grit and survival. 

Figure Two - 1.36-inch long Folsom dart point made from a typical, semi-translucent Flattop chalcedony. I surface found this 12,600-year-old artifact on private land in Weld County,
Colorado on August 30, 2007. The source of the material at Flattop Butte is 
approximately twenty miles from where I found this Folsom point. 
John Bradford Branney Collection.  

The highest quality stone for making projectile points and stone tools comes from different forms of quartz. Quartz is composed of silica and oxygen, the two most common elements on the planet. Quartz has many flavors and crystal structures and can differ in color, texture, and minor chemical elements. In this article, I explore one variety of quartz favored by prehistoric people for thousands of years called Flattop chalcedony. Chalcedony is a general term describing a fine-grained or cryptocrystalline variety of quartz with a texture varying between waxy and grainy. Chalcedony ranges from nearly opaque to translucent and is found in a variety of colors including white, gray, blue, brown, red, and every shade in between. Some other rock types that fall under the chalcedony family include agate, moss agate, onyx, sardonyx, prase, and chrysoprase. 

Figure Three - Prehistoric rock quarry at Flattop Butte in northern Colorado. The butte lies on
private land and is now closed to visitors. The new owners prosecute trespassers.
Photographed by the author in August 2001 when the land was still accessible.

For thousands and thousands of years, Paleoindians and later prehistoric people visited what we now call Flattop Butte in Logan County, Colorado (figure three). There, those prehistoric people mined chalcedony from veins within the butte. Flattop Butte is composed of tuffaceous siltstone, sandstone, and thin limestone stringers in what is called the White River Group of geological formations. The rocks that comprise Flattop Butte were originally deposited as sediments sometime between thirty-four and twenty-three million years ago in the Oligocene Epoch.    

So, what were the high plains of northeastern Colorado like during the Oligocene Epoch? The landscape was a whole lot different than it looks today (figure four)! For one thing, the climate was a whole lot hotter, and prior to the Oligocene Epoch in the Paleocene and Eocene Epochs, the landscape went through a long period of exposure and erosion. Then, at the beginning of the Oligocene, volcanic activity in the Absaroka-Yellowstone area spewed vast amounts of silica-rich volcanic ash into the air. Massive amounts of sedimentation filled in the previous highs and lows of the earlier topography and created a terrain of very low relief with meandering streams and wide floodplains. Geological evidence indicates that during the Oligocene there was massive flooding which laid down thick layers of mud and sand and volcanic ash which later consolidated into tuffaceous sandstones, siltstones, shales, and limestones.

Figure Four  - Mural of the Early Oligocene on the high plains 
by Jay Matternes for National Geographic Magazine.
Note the volcanic activity in the background.   

The high plains and mountains went through a long period of aggradation over several million years where sediments spilled out of the mountains onto the plains. Aggradation occurs when the supply of sediment is greater than the amount of material that the depositional system is capable of transporting. Large amounts of sediment clogged the river systems and increased the elevation of the high plains during the Oligocene. Even today, some mountains in Wyoming and Colorado have a partial blanket of Oligocene sediments. 

The depiction of life and landscape in figure four shows that strange and extinct animals were abundant during the Oligocene Epoch and bits and pieces of fossilized bone are commonly found in eroded geological formations. Many of the fossilized bones are separated from the original skeletons and show evidence of rodent gnawing, providing further evidence of a terrestrial depositional environment. 

   

Figure Five - 1.6-inch-long James Allen dart point surface found on private land near 

Flattop Butte in northeastern Colorado. The material is a semi-translucent, pale red

Flattop chalcedony. The age of the artifact is north of 9000 years.  

John Bradford Branney Collection.   

How did the chalcedony form at Flattop Butte? Sand, silt, volcanic ash, and limestone were deposited and consolidated into bedrock at the site. Saturated with silica, groundwater seeped into the fractures and voids within the geological formation. Where did that silica come from? Most likely from the volcanic ash that spewed from volcanoes to the northwest and covered the countryside for hundreds of miles with thick blankets of ash. Then, when the groundwater in the nooks and crannies of the bedrock evaporated, it left behind a silica precipitate. Over thousands or millions of years, silicate minerals filled the voids within the bedrock, leaving veins of chalcedony.  

Around thirteen or fourteen or maybe fifteen thousand years ago, humans showed up at Flattop Butte. How they discovered the tool stone at the summit is anyone's guess. Perhaps, those First Americans noticed chalcedony on the surface of the ground and when they needed more, they mined the top of the butte creating pits everywhere. Greiser (1983) documented over two hundred mine pits on top of Flattop Butte where it appears prehistoric people dug through the caprock in pursuit of the treasured tool stone. 

Figure Six- Piles of Flattop chalcedony chipping debris at a prehistoric campsite 

on private land in the vicinity of Flattop Butte. The author took this 

photograph on April 2, 2014. 

Hoard et al (1993) described a typical piece of Flattop chalcedony as lavender gray with a dull luster and small white inclusions. Lavender and gray are the two most prominent colors and can range from opaque to semi-translucent with the semi-translucent pieces having the smoothest texture. Flattop chalcedony colors range from white, gray, brown, lavender, pink (what I call pale red), and reddish purple. Figure six is a photograph I took at a prehistoric campsite near Flattop Butte. The photograph exhibits the wide range of colors and textures found in Flattop chalcedony chipping debris.  

The Paleoindians in my book series were nomadic hunters and gatherers. Archaeological evidence points out that Paleoindians led simple but dangerous lifestyles. The Paleoindian characters in my books were always on the move chasing the biggest meal ticket around, roaming bison herds. Since Paleoindians were traveling about and exploring new territories, they did not know what to expect so they carried some of their favorite raw materials with them. If a need for a new projectile point or tool popped up, they would have enough material from their last stop to meet an emergency. And even if they did not use the raw material themselves, they could trade it along the trail to other humans for something of equal value. 

As a lifelong artifact hunter, it is not uncommon for me to find stone tools or projectile points, or chipping debris originating at rock quarries from other geographical locations. There are tons of archaeological evidence that indicates that Paleoindians and even later prehistoric cultures utilized hoarding and a "have material, will travel" strategy. 

Figure Six - Clovis spear/knife form surface found on private land in Keith County, Nebraska 

by Kevin Hammond. Was the material sourced from Flattop Butte or another 

White River chalcedony source in Nebraska or South Dakota? Chemical 

analysis of the material could determine that.    

John Bradford Branney Collection.  

As an example of that strategy, Hoard et al (1993) determined through chemical analysis that several artifacts from the Eckles Clovis site in north central Kansas were chalcedony sourced from Flattop Butte in Logan County, Colorado, some two hundred eighty miles to the northwest. In my lifelong pursuit of artifacts, I have found artifacts and chipping debris made of Flattop chalcedony in Wyoming, at least two hundred miles away from the source at Flattop Butte. However, as Hoard cautions, the White River Group of geological formations produced similar-looking chalcedonies in southeastern Wyoming, western Nebraska, and southwestern South Dakota (see figure six).    

By the end of the SHADOWS on the TRAIL Pentalogy,  my main characters arrived at a campsite near the rock quarry at Flattop Butte, and today I am still finding artifacts that they made from Flattop chalcedony.   

Figure Seven - 2.3 inch long, Pelican Lake knife form made from what I 
call a very pale orange, semi-translucent Flattop chalcedony. I surface 
found this artifact on 9/27/1986 in Weld County, Colorado.
The age is Late Archaic at around 2000 and 3000 years old.
John Bradford Branney Collection.  

Greiser, S. 

1983    A Preliminary Statement About Quarrying at Flattop Mesa. Southwestern Lore 49-(4): 6-14.  

Hoard, Robert J., John R. Bozell, Steven R. Holen, Michael D. Glascock, Hector Neff, and J. Michael Elam

1993    Source Determination of White River Group Silicates from Two Archaeological Sites in the Great Plains. American Antiquity. Vol. 58, No. 4 (Oct. 1993), pp. 698-710 (13 pages). Cambridge University Press. 

Recollections...

In my early years of high school, I began contemplating what I would do for the rest of my life. Since rock star was out because I did not even play a musical instrument, I looked at other options. My parents and I conversed on this subject several times. I mentioned to them that I really wanted to be an archaeologist. After all, my passion for hunting arrowheads started about the same time I learned to walk. A family friend in Casper, Wyoming was a consulting geologist in the oil and gas industry. My parents knew that their geologist friend did pretty well for himself and his family, so they suggested to me that while I might find a bit of fame digging up bison bones as an archaeologist, I would never find fortune doing that. My parents convinced me that people would always need oil and gas and coal, and with the money I made in those industries, I could retire early and hunt for prehistoric artifacts to my heart's content. I took their advice and they were right. 

My prehistoric adventures from the SHADOWS on the TRAIL PENTALOGY are available at John Bradford Branney Books.