The Paleoindian Fluted Point: Dart or Spear Armature? The Identification of Paleoindian Delivery Technology Through the Analysis of Lithic Fracture Velocity

Summary

J. Whittaker: “Velocity-dependent fractures on fluted points reveal fracture rates associated with high-velocity impacts, indicating the use of the spearthrower” No clear evidence of Clovis atlatl, but early dates on hooks from Marmes Rockshelter and Warm Mineral Springs, both 9-10,000 BP, others. Summarizes Clovis and Folsom tool kits and hunting strategies. Problems of classifying points as dart or arrow tips, criticizes Odell’s flake point hypothesis – accidental fractures look similar. Fracture surface features on flakes reflect manufacture. Relation between Wallner lines and fracture origin reflects velocity of fracture. [Fracture mechanics details and derivation of fracture velocities difficult to understand, illustrations in my copy reproduced poorly.] Test on manufacturing techniques, with velocity distinguishing pressure, soft percussion and indirect perc, and hard hammer perc, but variable and overlapping, especially pressure. Impact fracture should be in the “dynamic loading” or high speed range of fracture propagation.

Problems of reconstructing hafting system for experiments [good example of reasoning from variety of evidence]. Uses flute width to estimate shaft diameters of 12-17 mm. Compares Huckell 1982 and Frison 1989 experiments. Prehistoric darts (mostly SW and Gt Basin) 3-19 mm diameter, foreshafts 6-19 mm diameters, most 8-11 mm. Coleman, boar hunter, prefers 221 cm long, 11mm diam, Clovis point 20-30 gm, total weight 240 gm, similar to Australian average weight of 246 gm.

Ethnog hunting range data poor, suggest accurate range 10-30 m.

Coleman's Georgia boar hunts - 51 hits, 58 misses, kills from 3-46 m, average 15 m. Measured spearthrower velocities, see Hutchings and Bruchert 1997.

Point fracture velocity tests using large cross bow at short range, shots against stone and beef ribs. All points obsidian, more or less Clovis form. Darts 167-296 gms, velocities averaged 35.6 m/sec, kinetic energy 117-165 Joules. Fracture velocity data from 53 points, spanned rapid (38%) and dynamic (62%) loading rate regimes. In other words, lots of variability, with fracture velocities “spanning full range of fracture velocities associated with stone tool manufacture. This suggests that the impact fracturing of lithic projectiles is a complex process which involves more than just those fractures caused by the extreme force of sudden impact.” Fracture velocity less affected by impacted material (stone or rib) than in manufacture experiments. Compared also javelin, spear, and arrow, and dropped darts. Spear continuous pressure produces quasi-static (slow) fracture, javelin much slower than dart and arrow, which are similar. Only arrow and dart produce fractures in the upper dynamic loading range.

[I have trouble believing that projectile velocity makes much difference to fracture velocities which are 10-50 times greater, ie projectile velocities around 35 m/s, fracture velocities from 454-2231 m/sec. Also, note fairly consistent dart velocity, highly variable fracture velocity. His explanation that fractures are complex, and one impact may produce evidence of several speeds may be right. He would say lower ranges aren’t definitive, but high range only achieved by arrow or dart.]

Examined archaeological specimens, total of 668, mostly fluted points and fragments, from many sites. Clovis – 19 pts with “velocity dependent” fracture features, 63% in “dynamic” range. Eight Folsom points, all within dynamic range. [Problems here include small sample, and calculations of fracture velocity apparently based on Modoc obsidian rather than actual material of points.]

Low fracture velocities in flute scars suggest pressure fluting of Clovis.

[Very interesting, high potential. I want to see other similar studies before I’m fully convinced.]

This Resource is Part of the Following Collections

• EXARC Experimental Archaeology Collection

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Individual & Institutional Roles

Contact(s): EXARC Experimental Archaeology Collection Manager

Record Identifiers

ExArc Id(s): 10178

Notes

Rights & Attribution: The information in this record was originally compiled by Dr. Roeland Paardekooper, EXARC Director.