DEBITAGE ANALYSIS

University of Montana

Anty 455 Artifact Analysis Final Project

Elizabeth Rush 5/9/14

DEBITAGE ANALYSIS

INTRODUCTION

Debitage analysis is an important way to gain a better

understanding of the lithic processing and use of different

areas in an archaeological site. The measurements of

different attributes on lithic debitage can provide

information on the type of stone tool manufacturing that

took place and provide insight into what the site was used

for. The goal of this debitage analysis was to answer the

question of whether or not similar lithic processing was

going on at two separate areas of site 13 that Carlin Malouf

discovered during a pipeline survey in Colorado in the

1950’s. The area Malouf surveyed was labeled as site 13,

and was near the remains of a pit house.

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This debitage analysis was modeled after Sullivan and

Rozen’s “interpretation free” technique, meaning the

measurements would be taken without noting which specific

method of production was used, or where in the reduction

process each flake was created. Their “interpretation

free” method of debitage analysis is usually done by

creating a hierarchical key using different, specific

attributes to understand the types of flakes present in an

assemblage with the goal of creating a scientifically

replicable study (Sullivan and Rozen 1985). This debitage

analysis, however, used the attributes Sullivan and Rozen

suggested as means of comparing the two groups from site 13.

The Sullivan and Rozen attributes were used in the hopes of

analyzing if the two groups from site 13 had the same type

of flakes. Other appropriate attributes were also used to

examine similarities or differences between the two groups.

This debitage analysis also used analytical techniques

described by William Andrefsky, in regards to where on the

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flake measurements of particular attributes were taken, and

in doing an aggregate analysis of each piece of debitage’s

size.

The attributes that were selected and measured for each

group were flake size, flake weight, type of raw material,

whether or not the interior of the flake was discernible,

platform thickness and platform width, bulb of percussion

thickness, the presence of ripple marks on the flakes, and

the type of termination present on each flake.

Once all the attributes had been measured for both

groups out of site 13, the averages of the different

attributes were compared between the two groups, as well as

other non-numerical attributes. In comparing the two

groups, it appeared that there was similar stone tool

production happening at the two separate areas of site 13.

MATERIALS &

METHODS

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The first materials used for the analysis were Malouf’s

own records. The location of site 13 and site 14, which

were noted as being very similar sites, were drawn showing

their positions in the field. Site 13 is shown to be on

either side of the pipeline being surveyed. In Malouf’s

notes he said site 13 and 14 are very similar, that he

found similar flakes and the sites are geographically

close. The main materials used for the analysis were the

two groups of debitage found at separate areas of site 13.

The first group, group A, had a total of 11 pieces of

debitage. The second group, group B had a total of 46

pieces of debitage.

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Figure 1. Malouf’s Map of Site 13

The two groups of debitage were arranged on two

separate trays. The flakes were arranged by size and

appearance of raw material. Each lithic flake was

examined, and each attribute, if present was measured. The

flakes were measured for size using methods similar to an

aggregate analysis. Each flake was placed on a sheet of

paper with boxes of different sizes to recreate nested

screens, with the size in millimeters of each square. Each

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flake was also weighed individually on a digital scale in

grams. The platform of each flake was measured by

thickness and width due to the advice from Andrefsky’s

Lithics: Macroscopic Approaches to Analysis. In his publication,

Andrefsky stated it was difficult to recreate a measurement

for the platform due to different analysts measuring

different sides, so the platform was measured by the width

and the thickness, to make the measurements as accurate as

possible. The bulb of percussion was measured on each

flake at the maximum thickness of the bulb of percussion

(Andrefsky 1998). The lithics were examined closely to see

if the interior surface was visible. The interior surface

is indicated by marks that represent an applied force, such

as ripple marks (Sullivan and Rozen 1985). The lithics

were examined using a magnifying glass to identify the type

of raw material each flake was sourced from. The

magnifying glass made the crystalline structure of the

quartzite material more obvious, and aided in defining the

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type of raw material each flake was made of. The two

groups were examined to identify the types of terminations

present, and if the margins were intact or indicate they’ve

been broken. A margin is considered intact of it has a

feather or hinge termination present (Crabtree 1982).

Once all the flakes had been examined and attributes

(if present) recorded for each group, the numbers were

analyzed and compared. The averages for each numerical

attribute were taken for each group for the numerical

comparison. The attributes that were analyzed

categorically were recorded for each group and compared.

For example, the presence of ripple marks was recorded on a

yes or no basis. The numbers of yes occurrences and

numbers of no occurrences were recorded for each categorical

attribute. A pivot table was created in excel to show the

average flake size and weight for each group to aid in

comparison. A T Test was done in excel to the attribute of

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flake weight to statistically analyze the difference between

the groups.

The purpose of recording the similarities or

differences between the averages of each attribute for each

group was to better understand the tangible similarities

between the lithic processing that took place at the two

locations in site 13. If the averages of the numerical

attributes were similar for both assemblages, then most

likely there was similar processing happening at both

locations.

RESULTS

The results of the attribute comparison were

interesting. The pivot tables of the flake’s size and

weight attributes show that group A had two lithics that

were much larger and heavier that skewed the data. The

large and heavy lithics were determined to be a partial core

and a possible tool. The possible partial core was made of

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quartzite and had many different negatives of where larger

flakes had been taken off from many different sides. The

possible tool was made of quartzite and had hinge

terminations, which could indicate the lithic wasn’t hit in

the correct area with the right amount of force in the

knapping process, but appeared to have been reworked on one

of the edges, as to still make use of the large quartzite

material (Crabtree 1982).

The pivot table also showed that, although group A had

some larger and heavier pieces, the average size for the

majority of the flakes was similar to that of group B.

Flake weight however, seemed to be more varied. Group B

had much smaller weights than Group A. This could speak to

the nature of the reduction happening at group B. More

smaller, thinner flakes with no platform could indicate

bifacial thinning was happening more with Group B (Andrefsky

2001).

Row LabelsAverage of Flake Size in mm Average of weight in grams

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Group13A1 70 166.3Group13A10 45 22.2Group13A11 35 6.8Group13A2 60 31.8Group13A3 60 90.8Group13A4 25 2.9Group13A5 40 15.8Group13A6 40 11.5Group13A7 40 5.6Group13A8 30 4.8Group13A9 30 2.3Grand Total 43.18181818 32.8Figure 2. Pivot Table of Group A

Row LabelsAverage of Flake Size in mm Average of weight in grams

Group13B1 50 25Group13B10 30 3.1Group13B11 25 2.8Group13B12 30 2.5Group13B13 30 2.2Group13B14 30 2.7Group13B15 45 7.6Group13B16 35 5.1Group13B17 35 6.7Group13B18 40 6.2Group13B19 30 3.9Group13B2 45 13.4Group13B20 25 2.2Group13B21 25 1.8Group13B22 25 1.6Group13B23 25 2.4Group13B24 30 4.9Group13B25 25 1.9Group13B26 30 2.6Group13B27 20 0.7Group13B28 25 2.4Group13B29 30 2.9Group13B3 35 7.1Group13B30 35 6.9Group13B31 20 0.6Group13B32 30 2.6Group13B33 25 1.8Group13B34 25 1.1Group13B35 20 2.1Group13B36 30 2.2

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Group13B37 20 0.7Group13B38 20 0.8Group13B39 20 0.8Group13B4 40 6.3Group13B40 20 0.7Group13B41 20 1.5Group13B42 20 0.5Group13B43 20 1.2Group13B44 20 0.6Group13B45 15 0.3Group13B46 20 0.6Group13B5 40 5.9Group13B6 40 7.6Group13B7 30 2.8Group13B8 30 4.3Group13B9 40 5.7Grand Total 28.69565217 3.680434783Figure 3. Pivot Table for Group B

A T -Test was done on the attribute of flake weight,

the results of the T test were greater than .05, which

meant there was reason to reject the idea that the two

groups are unrelated, and there is an 88% chance the groups

are actually related (Stone and Ellis 2006).

Figure 4. Results of T-Test

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Categorical attributes were also compared between the

two groups. The categorical data was skewed because of the

difference in size between the two groups. When analyzing

if the interior was discernible the results showed that for

both groups the interior was discernible more often than

not. Similar results occurred in the attribute of the

presence of ripple marks. There were no ripple marks

present for the majority of artifacts in both assemblages

than were present.

Interior Discernible NO YESGroup A 4 7Group B 9 37Figure 5. Interior Discernible

Presence of Ripple Marks

NO YES

Group A 7 4Group B 39 7Figure 6. Presence of Ripple Marks

The results of the analysis of the type of terminations

present showed that for both groups there were mostly

feathered and what could be considered broken margins.

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This could indicate that both groups were going through

similar lithic reduction processes.

Terminations

Feather

Step

Hinge

Feather/hinge

Feather/step

Broken

Feather/Hinge/Step

Group A 7 1 1 2Group B 17 1 2 7 7 11 1

Figure 7. Type of Terminations

The results for the average platform width and

thickness were similar for both groups, although, the

average bulb of percussion was significantly different

between the two groups.

Group Avg Weight (grams)

Avg FlakeSize(mm)

Avg Platform thickness(mm)

Avg Platform width(mm)

Avg Bulb of Percussion thickness(mm)

A 32.8 43.2 8.9 15.7 13.7B 3.7 28.7 4.7 16.4 5.3Figure 8. Averages of Numerical Attributes

The greatest difference between the two groups was the

amount of chert and amount of quartzite that made up both

assemblages. Group A had mostly chert but group B had

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majority of quartzite as the raw material. This doesn’t

necessarily mean the two groups are unrelated, as it is

more significant that both groups had the same two types of

raw material present.

Raw Material Chert QuartziteGroup A 8 3Group B 11 35Figure 9. Type of Raw Material

CONCLUSION

This debitage analysis used similar attributes Sullivan

and Rozen would have used when analyzing debitage

assemblages. The analysis showed that the interpretation

of where in the lithic reduction process each piece falls is

not completely necessary to conduct a comparison of two

debitage assemblages.

The importance of the context of where the assemblages

were found cannot be over stated, the context of any

artifact assemblage can aid in analysis, interpretation and

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understanding of the site. Malouf’s records of the site

proved very useful in better understanding the possible

relationship between the two groups. The use of

statistical analysis on groups of debitage is a helpful and

appropriate way to scientifically understand the

similarities between two assemblages. Most importantly,

this analysis did not rely on human interpretation, making

it easier to replicate and the results scientifically and

mathematically justified. The results of this analysis

showed there are significant similarities between the

assemblages, and that the two groups of debitage were

probably created using similar processing techniques by the

same or related groups of people.

REFERENCES

Andrefsky, William, Jr.1998 Lithics: Macroscopic Approaches to Analysis. Cambridge Manuals in Archaeology, Cambridge.

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Andrefsky, William, Jr.2001, Lithic Debitage: Context, Form, Meaning. University of Utah Press, Salt Lake City.

Crabtree, Don1982 An Introduction to Flintworking. Occasional Papers of the Idaho Museum of Natural History No. 28.

Stone, David, and Jon Ellis. "Evaluation of Means for small samples - The t-test.". http://www.chem.utoronto.ca/coursenotes/analsci/StatsTutorial/ttest.html (accessed April 30, 2014).

Sullivan, Alan P. III, and Kenneth C. Rozen 1985 Debitage Analysis and Archaeological Interpretation. American Antiquity 50(4): 755-779

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