Dome & Plane (D&P) -- A Biface Reduction Process

Tony Baker       December 1, 2000

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The significance and understanding of the D&P reduction process became evident after studying the bifaces from the Little River Clovis Complex (LRCC). The LRCC consists of four manufacturing sites; Adams 15Ch90, Boyd-Ledford 15Ch236, Roeder 15Ch482 and Ezell 15Ch483 (Yahnig in press). These sites are located on or very near a source of Hopkinsville chert. The New Clovis bifaces depicted and discussed on this page are from these sites and represent a very small, non scientific sample of the many collected by Carl Yahnig1.

The bifaces depicted here were all discards. An edge may have been expediently used, but basically the knapper reduced the biface to this stage and abandoned it. The arrangement is by width with the widest presented first. So, most likely, biface #1 was discarded at an earlier stage of reduction than biface #6. This arrangement depicts the reduction trajectory employed by the New Clovis people. It was from nodules to bifaces and projectiles. (Click on any of the images for a larger version.)

One of the criteria I used when selecting this group of bifaces to photograph was they all represented the D&P process. Sanders (1990) used the term "end thinning" (D&P) to make a distinction between it and fluting in his book on the Adams Site2. In the research for the book, he separated 118 bifaces into six stages (II-VII) of manufacture following a model developed by Callahan (Sanders 1990: 31-52). Bifaces belonging to the first three Stages (II-IV) were considered to be "end thinned" (D&P), while bifaces belonging to the last two stages (VI & VII) were considered to be fluted. Stage V contained no "end thinning" (D&P) or fluting by Callahan's definition.

Sanders (1990:44) wrote:

    "...fluting of the Clovis point preform during Stage VI is functionally distinct from the basal thinning [D&P] of specimens described in Stages II-IV. As has been clearly demonstrated with numerous examples, basal thinning (D&P) of bifaces during early reduction stages is largely a corrective measure used when lateral thinning efforts have been unsuccessful." (The acronym "D&P" will replace "end thinning" in the rest of the document.)

At the Adams site, one-third of the bifaces in each of Stages II-IV failed during planing. Total counts are 31 planing failures out of 95 bifaces (Sanders 1990:33-43). Realizing that planing must have also been successful, most likely the actual percentage of bifaces planed was greater than 33%. This large percentage is not indicative of corrective measures, but of standard reduction procedure. Since the planing failure frequency is almost equal in all three stages, it follows that D&P was probably standard procedure in each stage.

Sanders also argued that the platform preparation during the early stages of D&P was minimal compared to that of the final fluting of the New Clovis point (1990:45). This is no doubt correct because the smaller the biface, the more attention has to be paid to the platform for successful flake removal. However, the difference in platform preparation as argued by Sanders should not be used to indicate that D&P was different than fluting. The difference is D&P was intended to remove a flake that ran the length of the entire face. See bifaces #2, 3, 4 and 5. On the other hand, fluting at the Adams site was only intended to thin the base.

The LRCC bifaces collected by Carl Yahnig are a marvelous depiction of the D&P reduction process. From these bifaces it is obvious the process consisted of a number of repetitive steps that were repeated as many times as necessary. In the simplest terms the steps are:

D&P Reduction
Step #Step
0Flatten Face A
Cycle 1 1Dome Face B
2Plane Face B
Cycle 2 1Dome Face A
2Plane Face A
Cycle 31Dome Face B
2Plane Face B
Continue to repeat the cycle until desired thickness is achieved


D&P Reduction--in detail

Step 0--Flatten Face A
A large flake or spall removed very early after opening up a nodule was the beginning of the D&P process. If the spall did not have an acceptable flat face, then Step 0 had to be executed. If Step 0 was executed it was done only once because subsequent D&P faces provided the necessary flat face.

One way the New Clovis knappers accomplished flattening a face was with wide flakes that ran from edge to edge (outre passť). Flakes that travel from edge to edge remove any surface irregularities that might exist on that face. Bifaces 1 & 5 with their outre passť flake scars (left images) are classic examples of what I associate with Clovis. However, as I looked though the hundreds of bifaces that Carl had, I found few pieces like these. I was puzzled by the scarcity of this type of artifact until I began to understand the D&P process. Step 0 occurred only one time for any given biface, and sometimes not at all if a flat face was naturally present. Cycle 2 then obliterated the outre passť flake scars. Bifaces 1 & 5 are rare artifacts and one of the keys to understanding the D&P process. 5

Cycle 1--Step 1. Dome Face B
Step 1 was the first step in the repeatable cycle. This step had the purpose of creating a dome on Face B. The dome must lie along the center of the face and run from end to end. Often in the first cycle there was a raised area resulting from creating the spall. With very little work on the face the knapper was able to modify this raised area to create a satisfactory dome. However, in subsequent cycles, considerable work was required to dome a face because it had been flattened by the previous D&P.

The left image of Biface 13 shows some of the work that went into the creation of the dome on a subsequent cycle. A regular pattern of flakes was removed from the edges of the biface. These flakes terminated at the center of the face thus creating the dome. To remove these flakes from the edge, the edge had to be turned or beveled to favor flake remove from this face. Each time the edge is turned to dome the other face, the biface becomes narrower. Since the knapper desired a biface with a large width to thickness ratio, they had to proportionally remove more thickness in the planing step than they removed width when turning the edge.13

When the edges were turned to construct the dome, the proximal end where the planing blow was struck was also turned. As reported above, Sanders observed minimum platform preparation during the early biface stages (1990:45). His observations were correct, because during the earlier stages of planing, the LRCC knappers were employing off-margin striking (off-edge blow). Thick bifaces do not require the extreme accuracy of blow for successful planing so the knappers were saving time by not building platforms. The classic example of planing with off-margin striking is the creation of the Levallois flake.

In later cycles when the biface was thinner, a platform was constructed to be used as a target. This was done by positioning the margin (edge) at the appropriate distance from the face and then grinding it so it would not crush during impact. (The two conditions depicted in this image, off-margin and margin striking, will produce the same flake.)

To reiterate, Step 1 contains three sub-steps: 1) turn the edge, 2) create the dome, and 3) create the platform. If each of these sub-steps is performed correctly, then Step 2 will almost always be successful.

Cycle 1--Step 2. Plane Face B
Step 2 consisted of only one percussion blow that planed the dome created in Step 1. If successful, a single, wide D&P flake was removed from the proximal end to the distal end and a flat face that was parallel to the reverse face was the result. Because this single planing blow was responsible for a large portion of unfinished bifaces found in the archaeological record, I have chosen to make it a single Step in the dome & plane process. The most common fatal error while planing was the overshot or reverse hinge as depicted in the right image of Biface 2. It was abandoned after the D&P flake cut it into two pieces. If the overshot failure had occurred at a further distance from the proximal end the biface probably could have been salvaged. However, after this short overshot the biface was too thick for its length and the knapper chose to abandon it.

As stated earlier, successful planing is largely dependent on the flatness of the opposite face. Another way of saying the same thing, is the thickness of the biface must not change radically along its length. Sudden changes in thickness will almost always cause the S&P flake to hinge or reverse hinge at that juncture. Correct flatting of the reverse face yields a successful planing step.

Cycle 2 and subsequent cycles
At this juncture the biface had two flat faces. However, it probably was too thick, so the knapper just repeated Steps 1 and 2 again. Since both faces were flat, the knapper could in theory choose to dome the face he had just planed. The knapper could have even reversed the ends and plane from the distal end in the next step. All was possible after the two flat faces had been achieved.

D&P Reduction is Folsom Point Manufacture

Folsom point manufacture is D&P and its manufacturing steps have been known for many years and detailed by several authors. One of the more widely accepted set of steps can be found in FOLSOM TOOLS AND TECHNOLOGY at the Hanson Site, Wyoming by Frison and Bradley (1980). I used this set of steps when I created my web page Folsom Point Manufacture. Depicted in this table is the cross-reference between the D&P steps and the Frison-Bradley steps. The work performed in comparable steps was identical except the Folsom preforms were smaller. Consider the following examples.
Process Cross Reference Table
D&P CycleD&P StepsFolsom Steps by Frison & Bradley
02 & 3 ??
114 & 5
217 & 8
Folsom-1 is a classic example of the D&P reduction process. Step-0 was bypassed by utilizing the flat side of the flake (left image). On the opposite face, the edges were turned, a dome was created, and then the dome was planed (right image). The planning terminated prematurely and the preform broke. Folsom-1
Folsom-2 is a preform that was split down the middle of the D&P scar. Step-0 appears to have been bypassed similar to Folsom-1, but it was not. Face A was flattened by several large percussion flake scars. The edges were turned, a dome created, and the dome was planed on Face B (right image). The planing caused the D&P flake to overshoot and simultaneously split the preform. The overshot tip is refitted to the artifact. Click here for a different image of this artifact.Folsom-2
Folsom-3 is similar to Folsom-2. Step 0, was executed by the removal of some large percussion flakes, left image. The edges were turned, then a dome was created and planed on Face B (right image). The D&P flake overshot and the preform was lost. Click here for a different image of this artifact.Folsom-3
Folsom point manufacture appears to have employed the D&P process for only two cycles, the result being that each face was planed only once. There is evidence that the D&P cycle was repeated more than two cycles on certain occasions. A third cycle would cause the same face to be planed a second time. This second planing is sometime visible on the D&P flakes. In this image, notice the prior D&P scars on the dorsal face of the D&P flake. D&P Flakes

In summary, D&P reduction was employed by both the New Clovis and Folsom peoples. In both groups the objective was to produce a straight, flat biface as quickly as possible. New Clovis routinely planed the faces more than once, while Folsom only occasionally resorted to a second face planing. The other difference between the two groups is Folsom was performing D&P on smaller artifacts.

Proceed to:
Planing versus Fluting,
Old Clovis, New Clovis, and Folsom -- Theory and Summary,

or return to:
Introduction -- The Clovis/Folsom Transition,
Paleoindian & Other... Home Page


1 Bifaces from sites:
Adams: #2 & 8
Boyd-Ledford: #6, 7, 10, 11 & 14
Ezell #1, 3, 5, 9, 12, 13, 15 & 16
unknown #4

2 The collection that Sanders analyzed consisted of 1333 artifacts and belong to the Kentucky Heritage Commission. All but 84 of those artifacts were collected by the Commission in 1977. The 84 were donated by Carl Yahnig when he introduced the Commission to the Site. The artifacts I viewed were from the Adams, Boyd-Ledford, Roeder and Ezell sites and were separate from the Commission's collection. According to Carl Yahnig (2000: pers. com.) the artifacts I viewed were very similar to the ones Sanders studied from the Adams site.