Wednesday, March 11, 2015


Figure One. A 2.45 inch long Agate Basin projectile point at the top and Hell Gap projectile point on the bottom.
Most archaeological investigators believe that Agate Basin projectile points transitioned into Hell Gap projectile
points sometime around 10,000 years ago, give or take. This does not mean that Agate Basin projectile points
became obsolete or were not made. They continued to exist alongside Hell Gap projectile points for some time.   
It was 1958 and James Duguid, a future University of Wyoming geology student, was exploring an arroyo bank along an intermittent stream along the eastern flank of the Hartsville Uplift in southeast Wyoming. Duguid found an unidentified projectile point type eroding from the arroyo. In 1959, Duguid contacted archaeologist George A. Agogino at the University of Wyoming and showed him this unnamed projectile point. The unique projectile point intrigued Agogino who decided to investigate the area. Upon his return from the investigation, Agogino immediately opened a small research project to further investigate this area in southeast Wyoming called Hell Gap.

The rest is history. Fifty-five years later, the Hell Gap archaeological site is one of the most important archaeological discoveries in the western United States and that projectile point James Duguid found became a new projectile point type called Hell Gap. 

Figure Two. Winds of Eden, the third
and final book in the Shadows
on the Trail Trilogy.
Click for info on this book.   
The prehistoric trilogy I wrote, called the SHADOWS ON THE TRAIL TRILOGY, is about the Folsom People, who lived from 10,900 to 10,200 and for the most part, lived before both Agate Basin and Hell Gap Peoples. Although most archaeological investigators are unsure what connection existed between Folsom and Agate Basin People, most investigators believe that their was a connection between Agate Basin and Hell Gap Peoples and the evidence is in their projectile points. Many investigators believe that Hell Gap projectile point technology was derived from the older Agate Basin projectile point technology. 

You might be asking, what is an Agate Basin projectile point and a Hell Gap projectile point? Good question! There will be more on the technological differences later in the blog, but for now please 'eyeball' Figure One above which shows two projectile points, both made from a rock type called Knife River Chalcedony which is found in North Dakota. The top projectile point is an Agate Basin and the bottom projectile point is a Hell Gap. The manufacturing process that led to Hell Gap projectile points was a time continuation of the well developed Agate Basin manufacturing process. The makers of Hell Gap projectile point simply terminated their production process sooner than the makers of Agate Basin projectile points.        

Since this blog posting is about Hell Gap projectile points, let me briefly describe them. Hell Gap projectile points are medium to large lanceolate-shaped points that are similar to Agate Basin points, except that the Hell Gap has stem limitations and often times it has shoulders. On a Hell Gap projectile point, the stem is long and contracting. The Hell Gap projectile point has straight to concave side edges and a straight to concave basal edge. The stem edge is often ground and polished. The basal corners may be sharp to grounded. Let's now look at the Hell Gap example below.      

Figure Three. Side A of a Hell Gap spear / knife form from Colorado.
Figures Three and Four show sides A and B for a 2.55 inch long example of a classic Hell Gap spear / knife form surface found on private land in Morgan County, Colorado.              

Most investigators believe that 10,000 years ago is a good timeframe for when the Hell Gap Complex existed on the High Plains. As previously mentioned, the Hell Gap projectile point appears to have developed from the earlier Agate Basin projectile point type. In fact, the distinctive Hell Gap shoulder was beginning to develop on some Agate Basin projectile points.
Figure Four. Side B of a Hell Gap spear / knife form from Colorado.

In the book The Casper Site, Frison and Bradley (1974) noted a special bifacial reduction process on quite a few Hell Gap specimens from the Casper Site in Wyoming. They noted that Hell Gap knappers achieved the general shape and regularity of the biface through serial percussion thinning on one side with a hammerstone. Spacing was carefully controlled and thinning flakes ran across the surface of the biface, reaching or nearly reaching the other edge of the biface (overshot).

Then, the knappers turned the bifaces over and thinned them from the opposite edge, creating bifaces with cross sections resembling parallelograms. After serial percussion thinning, the Hell Gap knapper shaped and straightened the margins of the biface using direct percussion with an antler or hammerstone or by selective pressure flaking. Bradley found in his study of Casper Site Hell Gap projectile points that some knappers used percussion only while others selectively retouched with pressure, especially at the base of the biface. Ultimately, Hell Gap knappers ended up creating bifaces that were lens-shaped.

Hell Gap knappers used platform isolation and moderate to heavy grinding to prepare the striking 
platforms for percussion flaking. Unlike Clovis striking platforms, Hell Gap knappers used smaller and more convex-shaped platforms.

I hope you have enjoyed this blog posting on Hell Gap projectile points and perhaps in the future I will write another prehistoric trilogy, but this time using Agate Basin and Hell Gap Peoples as the main characters. For now, pick up the SHADOWS ON THE TRAIL TRILOGY at a better bookseller and check out the Folsom People. You will be glad you did.     

Figure Five. Shadows on the Trail, the first book in the Trilogy. Click for Info on This Book!