"The types of projectile breakage which occurred (during the Denver elephant project) were found to compare favorably with archaeological specimens"--------1982, Bruce B. Huckell, "The Denver Elephant Project: A Report On Experimentation With Thrusting Spears," Plains Anthropologist, Vol. 27, No. 97, August 1982, p. 217.
    "Stone points of any size or shape tend to break so easily that durability beyond a few uses was probably not an achievable goal."--------2006, Joseph Cheshier and Robert L. Kelly, "Projectile Point Shape And Durability: The Effect Of Thickness, Length," American Antiquity, Vol. 71, No. 2, p. 354.
    "A seventh rib from a seven-year-old individual (of extinct bison antiquus) displays the compression morphology of a projectile point impact on its lateral surface. Fragments of the projectile's tip are lodged inside the impact scar."------1999, Leland C. Bement, "Bison Hunting At Cooper Site," p. 104.
    "According to some experimental results, flute-like fractures, burin-like fractures, and bend break and burin-like fractures are typical of breakage caused by using the point as a dart or thrusting spear tip"--------2009, Jun Hashizume, "Paleoindian Projectile Point Breakage And Reshaping," Hell Gap, A Stratified Paleoindian Campsite At The Edge Of The Rockies, p. 282.
    "---most fracture specimens (of Lake Mojave points) resulted from bend force breaking along weaknesses in the raw materials as well as cracks produced during manufacture, but there were also examples of impact fractures."--------2002, Noel D. Justice, "Stone Age Spear And Arrow Points Of The Southwestern United States," p. 97.
     "Bending fractures were most commonly located at the neck, and resulted from impact on soft, yielding materials such as sod, but these breaks also resulted from impact on harder, yielding materials such as loose gravel."----2006, Gene L. Titmus and James C. Woods, "An Experimental Study Of Projectile Point Fracture Patterns," Journal Of California And Great Basin Anthropology, Vol. 8, No. 1, p. 43.
    "Fractures resulting from impact on a hard, unyielding surface such as a large boulder or an old, dried pine stump produced another common break best described as crushing"---------2006, Gene L. Titmus and James C. Woods, "An Experimental Study Of Projectile Point Fracture Patterns," Journal Of California And Great Basin Anthropology, Vol. 8, No. 1, p. 43.
    "On projectiles subjected to forces in-line with the long axis of the blade, and in cases where the impacted materials were somewhat yielding, such as live wood, the resulting fractures were primarily oriented longitudinally in the form of what could be termed burinations"---------2006, Gene L. Titmus and James C. Woods, "An Experimental Study Of Projectile Point Fracture Patterns," Journal Of California And Great Basin Anthropology, Vol. 8, No. 1, p. 45.
    "Of the 34 points employed in this study, fractures occurred most commonly on first throws, although a high survival rate was demonstrated on some specimens"---------2006, Gene L. Titmus and James C. Woods, "An Experimental Study Of Projectile Point Fracture Patterns," Journal Of California And Great Basin Anthropology, Vol. 8, No. 1, p. 43.

CLICK ON PICTURE FOR LARGER IMAGE
MISCELLANEOUS PROJECTILE POINTS
WITH IMPACT FRACTURES
 
FLAKED STONE PROJECTILE POINT
IMPACT FRACTURES

     Stone tools are often identified by their wear patterns. Archaeologists refer to this area of study as "use wear analysis." Some tools are more easily identified than others, especially those that were heavily used. Some examples of common types of wear patterns, caused from use, are scraping, cutting, hammering, drilling, digging, abrading, and piercing. Projectile points were designed specifically for piercing and cutting. As a result, they are on the receiving end of what might be called "extreme wear." They offer some of the most interesting types of fracturing patterns.

     In recent decades there have been several projectile point impact studies done for the purpose of acquiring statistical data on fracture patterns. Some of the more dramatic projects have used replicated Clovis tools and dead elephants as the target. One of the earliest experiments involved an elephant from a zoo in 1978. The experiment is known as the "The Denver Elephant Project," and was led by Smithsonian archaeologist Dennis Stanford. Another project in 1984, was led by University of Wyoming archaeologist George Frison and involved dead elephants from an elephant culling operation in Zimbabwe, Africa. Both of these experiments produced similar impact fractures as those found on ancient sites. Frison wrote, "These experiments allow a number of cautious observations on the manufacture, use, and effectiveness of Clovis weaponry." The projects also provided data on bone fractures, wood foreshaft breaks, butchering processes, projectile penetration depths and edge-wear analysis.

     The earliest discovery of projectile point impact damage on stone spear points comes from a site in the Kalahari Desert called Kanthu Pan 1 in South Africa. The age of the site is still being debated. The initial date of 500,000 years ago is extraordinarily early since the next earliest date for stone projectile points is 250,000 years ago. But what is most interesting about the Kanthu Pan 1 points is the fact that enough damaged examples were found to positively identify them as projectile points. Further experiments with replicas of Kanthu Pan 1 points also supports their use as projectile points. The replicas were hafted and shot into Springbok carcasses resulting in similar impact fractures as the ancient Kanthu Pan 1 points.

    Three more examples of experimental point fracture studies were published by Titmus and Woods, with atlatl darts, in 1986, Cheshier and Kelly, with arrows, in 2006 and George Odell and Frank Cowan, with arrows, in 1986. All three experiments recorded high rates of point damage from impacts against different types of materials. The Titmus/Woods study used various types of stone, soil and wood materials as their targets and the Cheshier/Kelly study used a dead white tail deer for their target.

    The Cheshier/Kelly arrow point impact study involved 50 arrows and produced an impact breakage rate of about 50% for first impacts. Twelve of their points survived 2 shots, 8 points survived 3 shots, 6 points were shot 4 times and 3 points survived 5, 6 and, 7 shots. The average number of attempts before a point broke was 2.68. On-the-other-hand, the Titmus/Woods study produced an impact breakage rate of 70% for first impacts. Twenty one out of thirty experimentally thrown points broke on the first attempt. The average number of attempts before a point broke was 2.1. Seven of the points were thrown either 2, 3, 4 or 5 times before they broke. One point was thrown 8 times and another was thrown 10 times. The Odell/Cowan study produced the same impact fracture rate as the Cheshier/Kelly study. Their average was 2.68 shots before the arrow point broke.

    Bradley (1982) identified use-damage and breaks as the two main categories of damage found on projectile points from the Agate Basin site. Use-damage includes mainly impact damage. An example of break damage might include a combination of use-damage and accidental damage, such as trampling or it might be a manufacturing break caused by resharpening. Bradley lists nine different subdivision types of projectile point break damage in the Agate Basin study as bend, constrained bend, radial, outre passe, perverse, radial bend, flaw, shear, and unknown. The different types of use-damage, that is usually caused by impact, was identified as generalized impact, impact burin, impact channel, and simple crushing. Use-damage on edges were described as irregular, deep, and abrupt flake removals and damage to the bases was identified as burin spall removals.

    The Titmus/Woods study describes three basic types of impact fractures in the form of bending, crushing and shearing. The most common type of break pattern is referred to as a bend break. These are described as fractures that are perpendicular to the point's length. They appear as clean hinge snaps at various locations, from the tip (distal end) to the haft.

   Crushing may be the second most common impact fracture. Crushing is usually located at the distal (tip) end and caused from hitting a relative hard surface, such as a bone. Crushing damage can occur at the tip and also along the edges or margins. The fracture pattern appears as a random mix of overlapping and heavily undulating flake removals that can also have step fracturing at the point of impact.

    A third and probably a less common form of projectile point impact damage is shearing or burin fracturing.  These are longitudinal edge breaks that leave right angle fractures to both faces. These types of fractures occur when the line of force is in-line with the long axis of the projectile point. Burination is also a term that is used to describe these types of breaks.

    Impact experiments have shown that projectile points had a high failure rate with nearly half or more breaking with their first use. Point design and quality of material are two features that influence the survival rate for a flaked stone projectile point. The thickness to length ratio seems to be the most important design factor that determines a point's durability. The Cheshire/Kelly study comments that, "A high thickness/length ratio increases a point's lifespan." Frison (1986) suggests that a Clovis point might need testing before confronting large Pleistocene mammals in order to give the hunter a better chance of success. He writes that, "A finished projectile point, however flawless its appearance, must have been subjected to rigorous testing before use in order to detect flaws such as crystal pockets or internal fractures that would appear during use."

    Projectile point impact studies are an important area of research. There are so many different types of flaked stone projectile points, it would be interesting to find out which ones were the best designs. Some types definitely seem to have a better survival rate than others. Table Rock, Haskett, and Agate Basin points might be good candidates as opposed to Snyders, St. Charles, and Hardin Barbed points that seem to have more snapped bases.

    One of the most important factors for the survival rate of any one type of projectile point is its resharpening characteristics. Notched Points that tended to break at their "necks" were discarded more often because re-basing is a more difficult procedure. On-the-other-hand, lanceolate shaped points that have simple but sturdy un-notched bases, like Haskett or Agate Basin points seem to be more resharpening-friendly. The ability to salvage a point by resharpening to increase its usable life-span is an important factor when considering successful flaked stone projectile point design.

    Projectile point impact fractures represent intriguing evidence of ancient hunting or warfare events. As prehistoric populations increased, warfare would become more common but a greater number of projectile points would have been used for hunting. The most unique impact fractures are those found on the earliest Paleo-Indian period dart and spear points. They were broken against the bodies of mega fauna animals like mammoths and mastodons and a long list of other animals that have been extinct for thousands of years.

"REFERENCES"

1979, Stanford, Dennis, "Bison Kill By Ice Age Hunters," National Geographic, Vol. 155, No. 1, pp. 114-121.
1982, Huckell, Bruce B., "The Denver Elephant Project: A Report On Experimentation With Thrusting Spears," Plains Anthropologist, Vol. 27, No. 97, August 1982, p. 217.
1982, Bradley, Bruce A., "Flaked Stone Technology And Typology," The Agate Basin Site, A Record Of The Paleoindian Occupation Of The Northwestern High Plains, pp, 197-198.
1986, Frison, George C., "Mammoth hunting And Butchering From A Perspective Of African Elephant Culling," The Colby Mammoth Site, Taphonomy And Archaeology Of A Clovis Kill In Northern Wyoming, pp. 115-134.
1987, Bradley, Bruce A. & Frison, George C., "Projectile Points And Specialized Bifaces From The Horner Sire," The Horner Site, The Type Site Of The Cody Cultural Complex, pp. 216-217.
1997, Shea, John J., "Middle Paleolithic Spear Point Technology," Projectile Technology, pp. 79-106.
1999, Bement, Leland C., "Bison Hunting At Cooper Site," p. 104.
2002, Justice, Noel D., "Stone Age Spear And Arrow Points Of The Southwestern United States," p. 97.
2006, Joseph Cheshier, Joseph & Kelly, Robert L., "Projectile Point Shape And Durability: The Effect Of Thickness, Length," American Antiquity, Vol. 71, No. 2, p. 354.
2006, Titmus, Gene L. & Woods, James C., "An Experimental Study Of Projectile Point Fracture Patterns," Journal Of California And Great Basin Anthropology, Vol. 8, No. 1, p. 43.
2006, Meltzer, David J., "Artifacts, Technological Organization, And Mobility," Folsom, New Archaeological Investigations Of A Classic Paleoindian Bison Kill, p. 285.
2009, Hashizume, Jun, "Paleoindian Projectile Point Breakage And Reshaping," Hell Gap, A Stratified Paleoindian Campsite At The Edge Of The Rockies, p. 282.
2009, Sano, Katsuhiro, "Hunting Evidence From Stone Artifacts From The Magdalenian Cave Site Bois Laiterie, Belgium: A fracture Analysis," Quartar 56, pp. 67-86.
2012, Bower, Bruce, "Oldest Examples Of Hunting Weapon Uncovered In South Africa," Science News, Dec. 15, 2012, Vol. 182, No.12, p. 5.

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