Stone Tool Analysis in A Digital Environment:

1. Stone Tool Analysis in A Digital Environment: Digital Imaging applied to a trampling experiment of edge and surface attrition in obsidian Authors: E.S. Lohse, C. Schou, and D. Sammons

2. Lit-review: specific to trampling Issues on recognizing trampling attrition vs. patterned use wear Flenniken and Haggerty 1979 Gifford-Gonzalez et al. 1985 Pryor 1988 Nielsen 1991 McBrearty et al. 1998 Ideas on character of trampling attrition Shea and Klenck 1993 McBrearty et al. 1998 Damage from agricultural equipment Prost 1988 Mallouf 1981

3. Research Context Key to effective interpretation of lithic materials in archaeology is consistent discrimination of unintentional attrition from patterned attrition resulting from deliberate manufacture and use. Digital imaging allows accurate measurement of micropatterns important in defining distinctive patterns of attrition. A trampling experiment was designed that controlled for forces of compression, variability in raw materials, and depositional environment.

4. Trampling Study: Research Hypothesis Hypothesis (Ho): There will be no significant difference in edge damage and surface attrition between thick blocky primary obsidian conchoidal flakes and small, thin tertiary obsidian conchoidal flakes in a constant depositional environment exposed to controlled trampling.

5. Trampling Study: Forms

6. Concept Map: Attrition Potential

7. Trampling Study: Parameters Study group: N=67 conchoidal flakes removed from a single Glass Buttes obsidian core through free-hand percussion; flakes arranged in four sampling strata: 1. Blocky, thick primary removals 2. Thinner, secondary removals 3. Smaller, thin symmetrical tertiary removals 4. Small thin symmetrical blades Depositional environment: All N=67 flakes were placed in a trampling box: 1. Box dimensions: 2X4� in outline and 6" in depth 2. Box strata: a. Plywood base: �" b. Clay loam bed: 2" c. Fine earth layer: 2" d. Fine sand layer: 2"

8. Trampling Study: Methodology Methodology: 1.��Unmodified flakes were collected as removed from the core 2.��Unmodified flakes were photographed with a digital camera at 300 dpi resolution and saved at 2" maximum dimension:Ventral and Dorsal views 3.���Unmodified flakes were randomly scattered in the trampling box and raked below the surface with analysts' fingers 4.���The trampling box was placed at the door of the classroom and students were asked to walk through the box in and out of the classroom 5.���At the end of one week (3 classes; N=25 tramplers; two trips) the specimens were removed from the box 6.���Trampling and recording procedures were repeated over the course of three weeks.

9. Surface Plots All specimens were recorded as unmodified digital images and as surface plots recording pixel values Surface plots are three-dimensional representations of the intensity of an image X = length Y = width Z = height Viewpoint: elevation provides perspective from 0-90 degrees; rotation moves the viewer around the object in a 180 degree arc Surface plots could then be reduced to more simplified images using a range of filters and transforms to derive accurate edge boundaries

10. Need to Simplify Image for Data Recording To simplify recording, a practical schema was applied This schema allowed analysts to delineate measurement areas, greatly reducing areal coverage requirements Categories relate to projected differences in potential attrition relative to structural characteristics of the flake

11. Recording Random Attrition: Proportional Areas

12. Recording Patterned Attrition: Proportional Areas

13. Measurement in Pixel Environment

14. Real Images to Surface Plots

15. AOIs and Edge Rotations

16. Perspective in Reading the Plots

17. Trampling Study (1-3 weeks)

18. Results: No significant attrition over three trials Thin edges and surfaces showed no measurable attrition Why? Infer that sand matrix (grain size and texture) cushioned and distributed weight of foot traffic, allowing fragile flake edges and surfaces to rotate and still be uniformly supported Next step: manipulate sand matrix, including more variable grain size and texture Goal: understand breakage by relating attrition characteristics to variable grain size and grain texture

19. Conclusions Trampling Exercise and Archaeological Context: Problems with sand Digital Imaging and Analysis

20. Problems with the sand It appears that the sand was too fine, very regular in size and surface texture This allowed obsidian flakes to be evenly supported by the sand as compressive forces moved the flakes rotationally through the matrix

21. Overview: Sand Robertson (1990) CPT soil classification scheme. 1 = Sensitive, fine grained2 = Organic soils-peats3 = Clays-clay to silty clay4 = Silt mixtures-clayey silt to silty clay5 = Sands mixtures-silty sand to sandy silts6 = Sands-clean sand to silty sand 7 = Gravelly sand to sand8 = Very stiff sand to clayey sand*9 = Very stiff, fine grained* * Heavily overconsolidated or cemented The United States Golf Association considers seven factors when selecting bunker sand: particle size, particle shape and penetrometer value, crusting potential, chemical reaction and hardness, infiltration rate, color, and overall playing quality. Depending upon your location and climate, how you rank these factors may vary slightly. The biggest factor, the fried egg test, or in testing terminology, the Penetrometer value. The penetrometer value measures the energy required to bury a ball in sand. This value shows the ability of sand to resist the golf ball from burying, or in more scientific terms, its resistance to compression.

22. Sand Mix and Penetration

23. Measuring Sand Characteristics Ball-lie Rating Penetrometer Value (kg/cm2) Rating High< 1.8 Undesirable Moderate1.8 to 2.2 Acceptable Slight2.2 to 2.4 Acceptable Very Low> 2.4 Desirable Shape-Crusting or Set-Up Rating Rounded Severe Undesirable Sub-Rounded to Mixed Slight to Moderate Acceptable Angular None Desirable

24. USGA Sand Sorting

25. Potential for Digital Imaging Digital imaging allows automated recording of complex shapes in a controlled environment (scale, lighting, measurement) Measurement will be accurate to the level of a single pixel value and allows recording of complex shapes Measurement in a digital environment will allow creation of ratios and proportional area measurements applicable to a range of research questions in lithic analysis in archaeology

26. Archaeological Conclusions McBrearty et al. 1998 published these conclusions: Found a high degree of damage or edge modification to artifacts trampled in fine-grained sediments (cf. Flenniken and Haggerty 1979) Most damage found when artifacts were trampled on loam � artifact to artifact damage Damage related to penetrability of matrix (see also Nielsen 1991) Trampling attrition should be positively correlated with artifact densities This study: Finely sorted and rounded sand grains inhibit trampling attrition by supporting the artifacts in all rotational positions Attrition should be positively correlated with inducing variability in sand grain size and different sand textures Sandy matrices will probably inhibit attrition even in the case of high density artifact accumulations

27. Modification Trajectory: Steps 2-5

28. To Do: Induce Greater Attrition Rebuild the trampling experiment to induce greater attrition Create sand mix to emphasize greater size irregularity and angular surface texture Create thinner sand layer underlain by earth or loam layer Introduce more obsidian flakes and or reduce the trampling area to increase densities Employ digital imaging schema developed here to record attrition on obsidian specimens With enhanced attrition, use protocols to create accurate measurements Ratios Proportional areas Create statistical correlations between material and flake types and staged exposure to compression in variable sand matrices

29. Suggested References Beard, James B., Turf Management for Golf Courses, 2nd Ed. p. 259-281.� Ann Arbor Press,� Chelsea, MI. 2002. See Turf Diagnostics & Design Helping You Have Healthy Turf, http://www.turfdiag.com/bunker.htm#*_ Blott, Simon J., Ali M. Al-Dousari, Kenneth Pye and Samantha E. Saye, Three-Dimensional Characterization of Sand Grain Shape and Surface Texture Using a Nitrogen Gas Adsorption Technique,, Journal of Sedimentary Research; January 2004; v. 74; no. 1; p. 156-159. http://jsedres.geoscienceworld.org/cgi/content/full/74/1/156#TB1 Brown, K. W. and Thomas, J.C.� 1986.� Bunker Sand Selection.� Golf Course Management.� 54:64-70. Clement, W. P., Cardimona, S., and Kadinsky-Cade, K., 1997a, "Geophysical and geotechnical site characterization data at the Groundwater Remediation Field Laboratory, Dover Air Force Base, Dover, Delaware," Proc. SAGEEP, pp. 665-673. 

30. References. Continued. Endres, Anthony L. and William P. Clement, Relating Cone Penetrometer Test Information to Geophysical Data: A Case Study. http://cgiss.boisestate.edu/~billc/SAGEEP98/CPT.html Flenniken, J. and and J. Haggerty. 1979. Trampling as an Agency in the Formation of Edge Damage: An Experiment in Lithic Technology. Northwest Anthropological Research Notes 13: 208-14. Gifford-Gonzalez, D.D. et al., 1985, The third dimension in site structure: an experiment in trampling and vertical displacement. American Antiquity 50: 803-818. Klute, A. (ed.), Hydraulic Conductivity of Saturated Soils.� 1986.� Methods of Soil Analysis Vol. 1, Agronomy 9:687-703.� Amer. Soc. of Agronomy, Madison,� WI. Mallouf, Robert J., 1981, A Case Study of Plow Damage to Chert Artifacts: the Brookeen Creek Cache, Hill County, Texas. Texas Historical Commission, Office of the State Archaeologist, Report 33, Austin.

31. References. Continued. McBrearty, Sally et al., 1998, Tools underfoot: human trampling as an agent of lithic artifact edge modification, American Antiquity 63: 108-129. Nielsen, A. E., 1991, Trampling the Archaeological Record: An Experimental Study. American Antiquity 56(3): 483-503. Prost, Dominique, 1988, Essai d�etude sur les mecanismes d�enlevement produits par les facons agricoles et le pietinement humain sur les silex experimentaux. In Industries lithiques: Traceologie et technologie, S. Beyries (ed.), pp. 49-63. BAR International Series 411, Oxford. Pryor, John H., 1988, The effects of human trample damage on lithics: a consideration of crucial variables. Lithic Technology 17: 45-50.

32. References. Continued. Shea, J.J. and J.D. Klenck, 1993, An experimental investigation of the effects of trampling on the results of lithic microwear analysis, Journal of Archaeological Science 20: 175-194. Zhang, Z., and Tumay, M. T., 1996, "Simplification of soil classification charts derived from the cone penetration test," Geotechnical Testing Journal, v. 19, pp. 203-216.