Miller Margaret-Louise. Archaeological Approaches to Technology

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48 Heather M.-L. Miller: Archaeological Approaches to Technology

Shaping of

Hard Hammer

(if needed)

Collection

of Materials

for Polishing

Collection of

Hammer-stones

Stone Raw Material

COLLECTION

(including MINING)

Collection of

Soft Hammer

Materials

RAW MATERIAL

PROCUREMENT

MATERIALS

PREPARATION

‘PRIMARY’

PRODUCTION

Possible

REMOVAL of CORTEX

for Transport

(‘finishing’)

Possible

FORMATION of BLANKS

Possible

HEAT TREATMENT

FINISHING

Processes include: Abrasion, Knapping,

Transformation by Heat (usually earlier)

or Chemicals

Heather M.-L. Miller

2006

Shaping of Soft

Hammer

(Cutting, Carving)

Creation of

Abrasive

(If stone, crushing,

sorting, sieving)

SHAPING of OBJECT

Processes include:

Knapping, Cutting, Pulverizing, Abrasion

alone or combined

PRODUCTION PROCESS DIAGRAM FOR STONE

FIGURE 3.1 Generalized production process diagram for stone (greatly simplified).

Researchers have used both macroscopic and chemical analytical techniques

to source or provenience stone, to determine the location from which raw

materials were collected, especially for flints/cherts and obsidians (e.g., Ericson

and Purdy 1984; Luedtke 1992; Shackley 1997, and numerous articles in

Archaeometry and Journal of Archaeological Science).

Extractive-Reductive Crafts 49

Functional (physical use) characteristics affect the choice of stone used

to make an object, depending on the requirements of the end-product. The

different mineral characteristics of different types of stone, such as mineral

composition, grain size and structure, affect their texture, hardness and tough-

ness (resiliency or durability). For different sorts of stone objects, different

functional requirements will be desired. Cutting or piercing tools requiring

a sharp edge are preferentially made out of stones whose mineral structure

allows easy formation of sharp edges, such as obsidian, chert and chalcedony

(agate or jasper). Less brittle (tougher) stones like quartzite can also be used

for cutting, but it is more difficult to flake these stones due to their more

blocky mineral structure, so if formation of a sharp edge is the main crite-

ria, these stone types will only be used if the easier-to-flake stone types are

not available. Other tools for which toughness is the primary criteria, such

as pounding implements, hoes, adzes, and often axes, will be formed from

stones which do not flake easily on impact, such as basalt, granite, or jade.

Grain size (coarseness or texture) can be as important a factor as toughness in

choosing materials to make effective grinding implements (Adams 2002). For

small sculptures or vessels, stones that do not shatter when shaped yet which

are relatively soft and fine-grained are often preferred, such as soapstones and

related minerals.

The choice of stone type is affected not only by the intended physical

function of the end product, however, but also by desired colors, patterns,

and reflective characteristics, and by any cultural symbolism associated with

particular stone types. This is obviously the case for stone used to make

jewelry, decorative items, or religious objects, but it may also be important

for tools in some cases. For example, a hunter might consider a projectile

point made from petrified wood to be a far more effective weapon for killing

particular animals than any other type of stone, due to its special symbolic

powers. He would thus go to great lengths to acquire this stone, even though its

flaking and penetrating properties might not be any more physically efficient

than more easily available lithic materials. Similarly, minimum standards of

strength and workability are necessary for architectural or sculptural stone,

but beyond those requirements particular types are often chosen with specific

cultural associations in mind, especially for public buildings.

The collection of stone can be as simple as picking up cobbles in a stream

bed, a physical task requiring few tools but one that can entail considerable

expertise to choose the correct materials. However, in many cases, preferred

types of stone had to be quarried; that is, dug, chipped or broken out of

sedimentary or block deposits. Cobbles deposited by water or glaciers are

found buried in sediments from which they can be collected by digging with

digging sticks if deposits are shallow, or more elaborate tools if deposits

are deep. Stone is also found in block deposits from which smaller portions

50 Heather M.-L. Miller: Archaeological Approaches to Technology

must be extracted, again using a variety of tools. The degree to which fire-

setting was used to quarry stone in the past is much debated; it certainly

did occur, but the prevalence and extent of its use is not clear. However,

for quarrying large blocks of architectural or sculptural stone, more precise

methods of splitting than fire-setting would have been used. Hodges (1989

[1976]: 108–111) discusses the tools and processes employed in splitting and

working stone used for architecture and sculpture. Stone quarrying could also

involve extraction techniques similar to those used for the quarrying of metal

ore, as discussed in Chapter 4.

Frequently, the stone collected by all of these methods was reduced to

smaller pieces at or near the collection site. The weathered outer skin or

cortex of the stone as well as any flaws or unwanted mineral deposits would

be removed to decrease weight for transport. Therefore, collection sites often

contain large quantities of primary flakes, flakes with cortex covering a large

proportion of their surface, as well as generalized blocky and jagged waste

material. Blanks might even be produced near the collection site, a block of

stone of the approximate size and shape needed for producing the planned

stone object or architectural piece. Bradley (1989) beautifully illustrates the

production of blanks for early North American stone tools, as well as the

potential versatility and transport advantages of blanks. Biagi and Cremaschi

(1991) provide an example of industrial-scale blank production of chert cores

for distribution to towns and cities across the Indus Valley, where the final

blades and drills were produced.

However, as archaeologists know all too well, people had to balance various

requirements in making choices, so that there were times when it was a

disadvantage to remove the cortex of stones at the collection site, even though

this greatly increased transport costs. For example, archaeologists conducting

ethnographic and experimental studies of stone bead production in the town

of Khambhat (Cambay) in India, found that entire agate nodules were typically

brought back to Khambhat from the source area (Kenoyer,etal.1991, 1994;

Roux 2000). Only a small window would be chipped in a nodule at the quarry

site, to determine its likely quality (Figure 3.2, left side). This was done for a

number of reasons. Most of the nodules were carefully heat-treated, to improve

working qualities and change the color of the agate, and this was done by

each workshop group prior to any knapping of the stone. Presumably each

craftsman preferred to oversee this stage of the process himself. In addition, it

was said that the practice of doing all work in the town, and transporting the

agate in nodule form from the mines, developed because of the long history

of banditry in the region (Kenoyer,etal.1994). Bandits preying on travelers

and traders were less likely to steal bags of raw nodules than valuable stone

beads or even semi-finished blanks.

Extractive-Reductive Crafts 51

FIGURE 3.2 Products and some debris from stages of production for agate/carnelian beads;

progression of production stages is from left to right.

This is a relatively recent case, where we have ethnographic accounts

to alert us to these unusual choices made in the location of this prepara-

tory stage of production. We seldom have this sort of information for the

past, but such information provides essential information about the nature

of economic and possibly political situations affecting the production of

these objects. This does not mean that the same thing did happen in the

past. But it does mean that archaeologists need to consider such possibili-

ties by checking the archaeological data for additional information. In this

case, archaeologists need to check both collection sites as well as other

settlement-based production sites for the presence or absence of primary

flakes and other sorts of debitage (debris from stone working), before they

assume that cortex removal primarily took place near the collection site.

This is why it is so important that source areas for raw materials are well-

documented by archaeologists, and why avocational flintknappers are encour-

aged to remove their own debitage and generally avoid disturbing old quarry

sites (Whittaker 1994).

In the Khambhat example, the heating of agate nodules is an important

stage of production, done prior to any shaping of the stone, or even the

removal of cortex (Figure 3.3). For some types of stone and some purposes,

ancient craftspeople used heat or chemicals to transform the stone, changing

its working properties and/or its color. The most widely known transformative

technique for stone is the heat treatment of chert or flint, thought to have been

used to decrease the number of tiny flaws in the material and thus improve its

52 Heather M.-L. Miller: Archaeological Approaches to Technology

FIGURE 3.3 Heat treatment of agate nodules inside pottery vessels, using rice husks as fuel in

a reducing atmosphere. Photo courtesy of Lisa Ferin.

working properties (Grifiths, et al. 1987; Luedtke 1992; Purdy 1982). In these

circumstances, heat treatment would obviously take place prior to the shap-

ing stage (Figures 3.4 and 3.1). As in the Khambhat example, color change

or enhancement may have been an additional or even the primary goal of

heat treatment. Heat treatment would still be done prior to working of the

stone, to improve the working quality of the stone as well as change the color.

Heat treatment might also be done again after the object was finished, to

deepen the color (Matarasso and Roux 2000). Color change or design enhance-

ment was the goal of most chemical methods of transformation, such as the

(a)

FIGURE 3.4 Experimental heat treatment of chert fragments: (a) placed on sand.

Extractive-Reductive Crafts 53

(b)

(c)

FIGURE 3.4 (Continued) Experimental heat treatment of chert fragments: (b) covered in more

sand; (c) buried under dirt and a fire set.

54 Heather M.-L. Miller: Archaeological Approaches to Technology

chemical dyeing of semiprecious stones like lapis, or the chemical etching

of designs on stone. However, these chemical transformative stages typically

took place after the shaping stage, often as one of the last stages of produc-

tion, as they were focused on the appearance of the final surface (Figure 3.1,

bottom).

SHAPING AND FINISHING METHODS

The shaping methods employed depend largely on the type of stone being

worked, particularly the hardness and the toughness (resilience) of the stone.

Obsidian and chert are very hard, but are very brittle, not tough or resilient.

Therefore, they are best shaped by the rapid process of knapping; other shaping

techniques are much slower and can cause them to shatter. Basalts and granites

are also hard but are relatively resilient, so that while they can be shaped with

difficulty by knapping, they can also be formed by abrading or by pulverizing

techniques such as pecking. Jades are similarly very hard and very tough,

and so are best formed by pulverizing and abrading. Soapstones are soft

and resilient, not brittle, so they are easily formed by cutting, but do not

knap well.

Once the type of stone is chosen, this largely dictates the methods of

shaping and finishing the material: knapping, cutting, pulverizing, and/or

abrading. Lithics are noteworthy for the degree to which physical constraints

imposed by the properties of the stone restrict choices in production methods.

Lithic specialists are especially interested in the physical constraints restricting

choice, as the restriction of possible production processes allows researchers

to identify production techniques, sequences, and even end-product shapes

on the basis of the debris left behind (Kardulias and Yerkes 2003). Innu-

merable experimental and ethnographic projects have been dedicated to this

end, including the ethnographic and experimental work done in Khambhat

(Cambay), India, described above.

Knapping

Knapped (or flaked) lithics are shaped by hitting the stone (percussion) and by

applying pressure. To briefly introduce the extensive terminology for knapped

lithics, the term core refers to the main block of stone, from which flakes

are struck off. Percussion techniques include hitting the core directly with

a hard object (stone, metal) or a soft object (wood, bone, antler) to detach

flakes (Figures 3.5a and 3.6). These are called hard hammer direct percus-

sion and soft hammer direct percussion, respectively. Indirect percussion occurs

when an object is used to strike a wooden or bone punch placed against

Extractive-Reductive Crafts 55

(a)

(e) (f)

(b)

H. Miller 2006

FIGURE 3.5 Illustrations of various percussive techniques for knapping: (a) direct percussion

with hard hammer; (b) indirect percussion; (c) block and anvil technique; (d) bipolar tech-

nique; (e) inverse indirect percussion; (f) pressure flaking. (Redrawn after Kenoyer n.d. and

Odell 2004.)

the core, detaching flakes from the core (Figure 3.5b). Although typically

thought of as a Paleolithic method, the use of hammers striking metal spikes

to quarry building stone or mine minerals is also a form of indirect percus-

sion. Even more complex systems exist, such as inverse indirect percussion

(Figures 3.5e and 3.7a & b) (Kenoyer, et al. 1991, 1994; Pelegrin 2000;

short videos of this technique are shown on the CD in Roux 2000). Anvil or

block and anvil techniques are also percussive, but in this case the core is hit

against a stationary stone called the anvil (Figure 3.5c). A similar process is

employed in the bipolar technique, used for small pebbles, where the pebble is

placed on an anvil (sometimes held with the fingers), and hit with a hammer-

stone (Figure 3.5d). This can create orange-segment-shaped primary flakes,

but the technique is especially characterized by the presence of two points

of percussion, one on each end of the flake; hence “bipolar” (Figure 3.8).

56 Heather M.-L. Miller: Archaeological Approaches to Technology

FIGURE 3.6 Creation of building stone blocks by knapping, using direct percussion with iron

hammers.

(a) (b)

FIGURE 3.7 Creation of agate beads by knapping using inverse indirect percussion: (a) Inayat

Hussain, mastercraftsman, and (b) workman in the Keseri Singh workshop. Photos courtesy of

Lisa Ferin.

This technique is typically used in areas where knappable stone is scarce, as

seen in the use of small river pebbles of obsidian in the areas around the

Columbia River of the Northwest Coast of North America (Liz Sobel, per-

sonal communication). For additional terminology, Odell (2004), Inizan et al.

(1992), Whittaker (1994), and Andrefsky (1998) contain extensive details

Extractive-Reductive Crafts 57

FIGURE 3.8 Flake of obsidian created by bipolar technique; note the two points of percussion.

of various production processes for knapped lithics, as well as illustrations of

tool and debris types.

These percussive techniques are used to shape stone objects. Pressure tech-

niques may then be used to refine the shape, sharpen edges, or smooth surfaces

(Figure 3.5f ). In pressure flaking, a small tool (usually an antler, bone, metal,

or wooden rounded point) is laid against the knapped edge and pushed gently

to remove a small flake—the flake comes off of the underside of the knapped

edge. By varying the angle at which the tool is held, the flintknapper can

take off flakes of varying thickness and length. A skilled flintknapper can

remove very long thin flakes which extend a great distance across the knapped

object, as is seen in projectile points and knives of the Paleoindian and Upper

Paleolithic periods in North America, Eurasia, and Africa. Pressure flaking is

generally used to reduce the thickness and refine the shape of such points

and knives, to make a serrated edge, or to sharpen a dull edge. Many of these

effects can also be achieved with percussive techniques as well, so care must

be taken when analyzing knapped artifacts. Knapped stone objects can also

be smoothed by grinding techniques after they are shaped; many agate and

jasper beads, bowls, and other objects produced in South Asia today are still

shaped by knapping, although no traces remain on their final highly polished

surfaces (e.g., Figure 3.2, right side).

Cutting (Sawing, Drilling, Groove-and-Snapping)

Some types of stone will not flake well, due to their mineral structure. The

softer varieties of such stones, including soapstone (talc or steatite), alabaster,

turquoise, and lapis lazuli, were and still are shaped primarily by cutting

methods (Figure 3.9). Cutting is the shaping of a stone using a tool that is much