A Proposed Method for Distinguishing Between Blades and Bladelets

Maney Publishing

A Proposed Method for Distinguishing Between Blades and BladeletsAuthor(s): Daniel KaufmanSource: Lithic Technology, Vol. 15, No. 1 (April 1986), pp. 34-40Published by: Maney PublishingStable URL: http://www.jstor.org/stable/41999848 .

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34

A Proposed Method for

Distinguishing Between Blades and Bladelets

Daniel Kaufman

University of Haifa Mt. Carmel, Haifa 31999 Israel

Abstract

In studies of lithic assemblages from the Le- vant, establishing metric parameters for distinguishing between blades and bladelets has been a recurrent problem . Recently, it has been shown that many assemblages simply do not fit the generalized definitions proposed by such researchers as Tixier and others. This paper presents a method for defining the two elements on an assemblage-specific basis thus providing a more valid foundation for defining interassemblage variability. The proposed method is based on the observation of length/width scattergrams and frequency histograms, and the application of discriminant analysis.

Introduction

The Epipaleolithic of the Levant has long been characterized on the basis of those lithic assemblages containing numerous bladelet blanks and microlithic tools which are defined by the presence of continuous retouch/backing along a lateral edge (Bar-Yosef 1970, 1981). More recently, assemblages of the Upper Paleolithic with bladelet technologies and microliths have been recognized and described (Ronen and V andermeer sch 1972; Fer- ring 1977; Gilead 1981; Marks 1981). It is generally accepted that the microlithic component of these assemblages is of considerable diagnostic impor- tance. However, little work has been done to more specifically define this component with the primary problem being the distinction between the

macrolithic element, or blades sensu stricto, and the microlithic element, or bladelets.

There have been a number of attempts to define subsets of blades on the basis of metric attributes including length, width, length/width ratios or com- binations of these. The most widely applied criteria are those proposed by Tixier (1963) in which bladelets are defined as having length/width ratios of equal to or greater than 2:1, maximum width of 12 mm, and maximum length of 50 mm He also in- cluded pieces longer than 50 mm on the condition that width did not exceed 12 mm. In addition, Tixier considered backed tools as microliths if their width did not exceed 9 mm. Another set of parameters was suggested by de Heinzelin (1962) where 30 mm and 10 mm were considered the maximum length and width, respectively, of bladelets. Other authors have suggested three subsets within the blade category based primarily on length. Marks (1968) considered those pieces 30 mm or less in length as microblades, those between 31-50 mm as bladelets, and those greater than 50 mm were classed as blades. Hassan (1972) utilized slightly different parameters with microblades being less than 25 mm long and bladelets falling between 25-49 mm.

The multiple definitions and terms outlined above are indicative of the problems in establishing a universal set of parameters, and there are also some inherent dangers involved in applying any of these schemes to particular assemblages. For example, it has recently been pointed out that Tixier's criteria are not always appropriate (Bar-Yosef in press; Marks 1976; Marks and Simmons 1977), and forcing the data to fit these parameters will often distort the true character of an assemblage. This, in turn, may obscure other important factors such as blank selection for tool manufacture. Further, such an application will mask over important interassemblage variability which could be explained in terms of cultural, chronological and/or regional factors, as seen in examples presented by Bar-Yosef (1981).

An Alternate Approach

Consideration of these problems led to an alternate approach which was applied to Upper Paleolithic assemblages from Israel (Kaufman 1981), several of which were characterized by a blade/bladelet technology. Through this procedure, the metric parameters of the bladelet element were defined separately for each specific assemblage with no attempt to apply a general set of parameters to all assemblages. This resulted in assemblage- specific descriptive statistics and a more valid base for drawing comparisons and defining in-



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terassemblage variability. The first part of the procedure includes the direct

observation of length/width scatter grams and frequency histograms of length and width for both tools and debitage. As will be seen, in assemblages containing large numbers of blades/bladelets, it was possible to see dichotomous distributions of length and width for the tools. This, however, was not the case for the debitage, and the frequency histograms of the two measurements, often strongly skewed toward the small element, were continuous and ex- hibited no clear bimodality.

The second part of the procedure consisted of employing discriminant analysis (Affifi and Azen 1972) as a classification technique. Discriminant analysis is a means of distinguishing between two a priori defined groups by weighting and linearly com- bining a set of variables so that the distances between the groups are maximized or, in other words, so that the groups are forced to be as distinct as possible. At one level, discriminant analysis allows for isolating the variable or set of variables which best discriminate between the groups. On another level, it is possible to classify unknown cases, within certain ranges of probability, into one of the defined groups. Thus, it is possible to calculate the probability of a given case being classified into a specific group as well as the probability that a member of that group would be as far from the group centroid as the specific case under consideration.

The bimodal distributions of length and width among the tools allowed for the establishing of two a priori defined groups: bladelet tools (microliths) and blade tools. The debitage comprised the unknown cases and, on the basis of the two discriminating variables of length and width, it was possible to classify these unknown cases as either bladelets or blades. The classification was done through the program DISCRIMINANT from the Statistical Package for the Social Sciences (Nie et al. 1975).

It should be pointed out that discriminant analysis is a multivariate technique and allows for considering the two variables of length and width together. However, in a series of experimental runs, it was found that using the two together gave a weaker discrimination between the groups than did applying them separately in a univariate model. Also, width was always a stronger discriminating variable than was length.

Regarding width, it can be argued that the crea- tion of a retouched or backed edge would reduce this measurement considerably and, thus, skew the results towards the more narrow pieces. However, in the example to be presented, fine Ouchtata retouch

is predominant, and it is felt that only a small por- tion of the width was removed.

The Application

The lithic assemblage from the site of Ein Agev East (Ferring 1977; Kaufman 1981) will serve as an example of the proposed procedure. The site is located in the central Negev highlands and belongs to the closing phase of the Levantine Upper Paleolithic, dating to between ca. 20,000 B.P. and 17,000 B.P.

The assemblage is characterized by a predominately blade/bladelet technology, and this class of debitage was the most frequently selected for tool manufacture. Worth noting is the presence of multiple core reduction strategies with one for blade production and the other for bladelet production. On the basis of techno-typological considera- tions, the assemblage belongs to the Ahmarian tradition of the Levantine Upper Paleolithic as recently defined by Gilead (1981) and Marks (1981).

Figures 1 and 2 are the length/width scattergrams for tools and debitage, respectively, while Figure 3 shows the frequency histograms for length and width for these two groups. For the tools, there is no reason to distinguish between pieces greater than or less than 9 mm. Rather, there is a definite hiatus in the scattergram between the microliths and the macroblade tools, and this is seen in the clearly bimodal distributions for width with the break oc- curring at 17 mm. Length of tools shows a similar distribution. The histograms for the debitage, on the other hand, are highly skewed toward the small element, but exhibit no clear bimodality. Also, in the debitage scattergram the distributions are much more uniform but there is a small gap which is centered at the approximate coordinate of 45 (length) and 15 (width). To break these distributions at either 12 mm width or 50 mm length would be wholly arbitrary.

Two discriminant analyses were done, one using length as the discriminating variable and the other using width. In each run, the microliths and macroblade tools were defined as the a priori groups, and the program provided the most likely grouping for the unclassified debitage. Table 1 sum- marizes the results of these analyses and shows the way in which the debitage was classified according to length and width. The notation P(G/X) is the probability of a case with a particular measurement being classified into the specific group. The notation P(X/G) is the probability that a case within the a priori defined group would be as far from the group centroid as the particular case being considered.



36

Figure 1. Ein Aqev Elast: Length/Width Scattergram for Blade Tools.

For width, the program classified all pieces through 19 mm as bladelets and those greater than or equal to 20 mm as blades. However, it should be noted that widths up to and including 16 mm have P(G/X) well above 0.9 and P(X/G) above 0.1. At the other extreme, the strongest classification for blades begins at 22 mm with a P(G/X) of 0.901. This makes the range between 17 mm and 21 mm dif- ficult to interpret, and because of the low P(G/X) it is necessary to question whether or not pieces within this range belong to either classification, the reason being that they fall within that large gap between the microliths and macroblade tools in Figure 1.

It was decided, therefore, to make the distinction between blades and bladelets on the basis of the strongest classification, which could be at either 22 mm or 16 mm. On the basis of the frequency histograms, the former value seemed too large and the smaller seemed the more logical choice. Also, it corresponds closely to the small gap in the debitage scattergram of Figure 2.

For length, it was decided to make the distinction between blades and bladelets at the same point as the discriminant analysis or between 54 mm and 55 mm. It is true that the values of 53 mm and 54 mm do have P(G/X) in the 0.5 range and slightly lower P(X/G), but the changes in these values are not of the same order of magnitude as those observed for width. Also, because width is the stronger discriminating variable, there is some reason to allow for flexibility in length as this will account for those few pieces which may have slightly larger length/width ratios. This also alleviates the problem encountered by Tixier of defining a length parameter and then stating that it may be exceeded in some cases.

For the Ein Aqev East assemblage, then, bladelets have been defined as having a maximum length of 54 mm and a maximum width of 16 mm, values which differ considerably from those suggested by Tixier (50 mm and 12 mm). Because these parameters correspond quite closely to the gap seen



37

Figure 2. Ein Aqev East: Length/Width Scattergram for Blade Debitage.

Figure 3. Ein Aqev East: Frequency Histograms for Length and Width of Blade Tools and Debitage.

in Figure 2, it is possible to draw a line diagonally from upper left to lower right through that space and assign those pieces to the left of the line the classification of bladelet and those to the right, the classification of blade. Figure 4 is a scattergram showing the resulting classification.

On the basis of this distinction between blades and bladelets, it is of interest to compare the metric attributes of tools and debitage for each of the groups as size seems to have been a major criterion in blank selection for tool manufacture. Tables 2 and 3 compare the measurements between debitage and



38

TABLE 1 Classification of Blade Debitage Based

on Discriminant Analysis

Length(mm) Cla 33* P(G/X) P(X/G)

50 1 .713 .138 51 1 .666 .122

52 1 .615 .107

53 1 .562 .09*4

54 1 .507 .081

55 2 .5*48 . 109

56 2 .602 .124

Widtn(mm) Class* P(G/X) P(X/G)

14 1 .913 .217

15 1 .978 .154

16 1 .94 9 .105

17 1 .889 .071

18 1 .773 .045

19 1 .590 .028

20 2 .621 .036 21 2 .785 .057

22 2 .901 .087

23 2 .956 .128

*Claas: 1 = bladelet; 2 = blade.

TABLE 2 Comparison of Metric Attributes (in mm)

of Blade Debitage and Tools

! ! Lengtn ! Widtn ! Tnick !

! ! Mean SD ¡ Mean SD ¡ Mean SD ! ! Debitage ! 62.8 22.2 ¡ 23.2 6.5 ! 8.1 4.3 ! ! ( N = 1 30 ) ! ; ; ; ! Tools I 79.8 27.1 ! 30.9 7.5 ! 11.7 5.4 ! ! (N =60 ) ! ! ; !

tools for blades and bladelets, respectively, and it is apparent that from the total debitage produced within each category, only a limited range was further utilized.

To verify this, a series of one-way analyses of variance was performed. The resulting ANOVA tables (Tables 4 and 5) show that the size differences

TABLE 3 Comparison of Metric Attributes (in mm)

of Bladelet Debitage and Tools

• i i il • i i i* ! ! Length ! Widtn ! Thick ! • i i il i* i il • i ! ---------- i - - - i i i i ---------- i - - - i i ! ! Mean SD ! Mean SD ' Mean SD ¡ • i i i i ! Debitage ! 29.9 7.2 ! 9.9 2.4 ! 2.7 1.2 ! ! (N=148) ! ! ! ! i i i i i ! Tools ! 27.1 4.9 ! 7.6 1.5 ! 1.9 0.6 ! ! (N=70) ! ¡ ¡ !

TABLE 4 ANOVA Tables for Comparisons of Length, Width, and Thickness Between Blade Debitage and Tools

LENGTH

Î Sum of guares Degrees of Freedom Mean Square ! ! Between Groups 1 1851 .6876 ( 1 ) 1 1851 .6875 ! ¡Witnin Groups 92419.5756 (188) 491.5935 I 'Total . 104E+. 06 (189) ! ! F = 24. 1087 SIG. = .0000 ¡

WIDTH

! Sum of Squares Degrees of Freedom Mean Square ! ¡Between Groups 2415.4041 ( 1) 2415.4041 ¡ ¡Witnin Groups 8754.7064 (188) 46.5676 ! ¡Total 11170.1105 (189) ¡ ! F = 51.8688 SIG. = .0000 ¡

THICKNESS

¡ Sum of Squares Degrees of Freedom Mean Square ¡ ¡Between Groups 534.6980 ( 1) 534.6980 ¡ ¡Witnin Groups 4150.1306 (188) 22.0752 ¡ ¡Total 4684.8287 (189) ¡ ! F = 24.2217 SIG. = .0000 ¡

between debitage and tools are highly significant. For the blades, selection was from the larger end of the total debitage spectrum. The reasons for this are not understood but with larger size comes greater strength and durability, and this may have been a primary concern of the flintknappers.

The opposite is true for the microliths which were selected from among the smaller bladelet blanks. Unfortunately, because the function of these tools remains unknown, it is not possible to determine why this would be the case. If microliths did, indeed, form parts of composite tools then hafting tech- niques may have imposed size restrictions but this idea requires further validation. Finally, as men- tioned earlier, it is possible to question the significance of the differences in width between the microlithic tools and bladelet debitage as this may be attributable to the retouch along the lateral edge. Again, though, it must be pointed out that the retouch here is minimal with little, if any, true back-



39

Figure 4. Ein Aqev East: Length/ Width Scattergram Showing Distinction Between (2) Blades and (1) Bladelets.

ing being present. It is highly unlikely that the fine Ouchtata retouch on these tools would have removed slightly more than 2 mm from the width of the original blank. Thus, selection is the most likely explanation for the variability between tools and debitage.

Conclusions

This paper has presented some of the difficulties involved in applying generalized parameters for distinguishing between blades and bladelets. In order to avoid the problem of masking over important differences between assemblages, a method was proposed based on the observation of length/width scattergrams and frequency histograms, together with the application of discriminant analysis, which allows for defining the

two elements on a site by site basis. For the example presented, the parameters established of 16 mm for width and 54 mm for length vary considerably from those defined by Tixier and give a more precise description of the assemblage. Of course, this classification of blades and bladelets is based on metric attributes only and does not necessarily in- dicate separate technologies for the production of the two elements. The metric definitions do, however, provide a basis for analyzing and comparing technological attributes such as platform preparation, platform angles, rim preparation, bulbs of percussion, etc. Such an approach can provide a more valid foundation for comparing assemblages and defining intersite variability which, in turn, may be explained on the basis of cultural, chronological and/or regional factors.



40

TABLES ANOVA Tables for Comparisons of Length, Width,

and Thickness Between Bladelet Debitage and Tools

LENGTH ! Sum of Squares Degrees of Freedom Mean Square ! ¡Between Groups 103.8291 ( 1) 103. 8291 ! ¡Witnin Groups 9412.6158 (216) 43.5769 ! ¡Total 9816.4150 (217) ! ! F = 9.2670 SIG. = .0026 j

WIDTH

! Sum of Squares Degrees of Freedom Mean Square ! ¡Between Groups 260.3798 ( 1) 260.3798 ¡ ¡Witnin Groups 983.0010 (216) 1.5509 ¡ ¡Total 1213.3807 (217) ! ¡ F = 57.2146 SIG. = .0000 ¡

THICKNESS

¡ Sum of Squares Degrees of Freedom Mean Square ¡ ¡Between Groups 31.3569 ( 1) 31.3569 ! ¡Witnin Groups 223.7791 (216) 1.0360 ¡ ¡Total 255.1363 (217) ! ¡ F r 30.2668 SIG. = .0000 ¡

References Cited

Affifi, A. A. and S. P. Azen 1972 Statistical Analysis: A Computer Oriented

Approach. Academic Press, New York.

Bar-Yosef, O. 1970 The Epipaleolithic Cultures of Palestine.

Ph.D. Dissertation, Hebrew University, Jerusalem.

1981 The Epipaleolithic Complexes in the Southern Levant. In Prehistoire de Levant, J. Cauvin and P. Sanlaville, eds.,pp.389-408. Editions du DNRS, Paris.

In The Mediterranean Levantine Epipaleo- press lithic as the Background to the "Neolithic

Revolution."

Ferring, R. 1977 The Late Upper Paleolithic Site of Ein

Aqev East. In Prehistory and Paleoen- vironments in the Central Negev, Israel, Vol II, A. Marks, ed.,pp.81-lll. SMU Press, Dallas.

Gilead, I. 1981 Upper Paleolithic Tool Assemblages from

the Negev and Sinai. In Prehistoire de Le- vant, J. Cauvin and P. Sanlaville, eds.,pp. 331-342. Editions du DNRS, Paris.

Hassan, F. 1972 Toward a Definition of 'Lames'; 'Lamelles'

and 'Micro-lamelles.' Libyca 20:163-167.

de Heinzelin, B. 1962 Manuel de Typologie des Industries Lithi-

ques. Institute Royal des Sciences Naturelles de Belgique, Bruxelles.

Kaufman, D. 1981 The Late Upper Paleolithic of the Levant:

An Analysis of the Lithic Assemblages. Ph.D. Dissertation, Southern Methodist University, Dallas.

Marks, A. 1968 The Halfan Industry. In The Prehistory of

Nubia, Vol I, F. Wendorf, ed., pp. 392-460. Fort Burgwin Research Center.

1976 Site D5: A Geometic Kebaran "A" Site in the Nahal Zin. In Prehistory and Paleoen- vironments in the Central Negev, Israel, Vol I, A. Marks, ed., pp. 293-316. SMU Press, Dallas.

1981 The Upper Paleolithic of the Negev. In Prehistoire de Levant, J. Cauvin and P. Sanlaville, eds.,pp. 343-352. Editions du DNRS, Paris.

Marks, A. and A. Simmons 1977 The Negev Kebaran of the Har Harif. In

Prehistory and Paleoenvironments in the Central Negev, Israel Vol II, A. Marks, ed., pp. 223-269. SMU Press, Dallas.

Nie, N., C. Hull, J. Jenkins, K. Steinbrenner, and D. Bent

1975 Statistical Package for the Social Sciences. McGraw-Hill, New York.

Ronen, A. and B. Vandermeersch 1972 The Upper Paleolithic Sequence in the

Cave of Qafza (Israel). Quaternaria XVI:189-201.

Tixier, J. 1963 Typologie de l'Epipaleopolithique du

Maghreb. Mémoires du Centre de Recher- ches Anthropologiques, Préhistoriques et Ethnographiques 2. Paris.



A Proposed Method for Distinguishing Between Blades and Bladelets

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