Australian Archaeology

Stone Artefacts: Procurement and Manufacture

Australian archaeology – Stone is regarded as the most visible surviving trace of prehistoric societies or human activity. This is due to the relative indestructibility of lithics compared to organic material in the archaeological record.

Unless preserved in anaerobic (oxygen-reduced), oxygen-reduced nic material deteriorates rapidly, leaving no trace for the archaeologist. The oldest surviving wooden artefacts in Australia come from the Wyrie swamp in southeast Australia and are about 10 000 years old.

While there is one site with wooden implements from the terminal Pleistocene, billions of stone artefacts are scattered around Australia, stretching back to the initial colonisation period. Undoubtedly, stone artefacts are important, but they only represent a fraction of cultural material, and wooden implements were heavily utilised.

We know this because many of the stone tools found are woodworking tools, whether they are hatchets, adzes or wood-shaving implements. The abundance of stone artefacts can present a lop-sided view of an ancient culture, especially when stone artefacts abound. This makes the stone appear to be the only form of material culture. However, the stone is a permeable record, and much can be gleaned from the study of lithics. For instance, Peter Hiscock, in a paper titled, Technological Responses To Risk in Holocene Australia, considers the development of new stone technologies as a response to environmental changes.

In Australian archaeology, as in other parts of the world, stone artefacts also contribute to developing a broad chronology for occupation simply because they span the total period. In an excavation, stone artefacts are often found in association with fireplaces. Fragments of charcoal in hearths associated with stone artefacts are dated, providing a radiocarbon date for each stratified layer. Using the Law of Superposition, a premise stating that the bottom layer is the oldest and that each successive layer above is younger, a site chronology can be developed. This, in turn, is combined with information from other sites and a general chronology at local, regional, and continent levels can be created.

Australian Archaeology Raw Materials

The function of a stone tool often decides what raw material is to be used, although if a particular material is not available, a second choice may be necessary. Stone implements form two broad groups: those used for cutting or scraping (flaked tools) and those used to grind or pound.

Flaked Tools: The raw material or core stone must have specific inherent properties when making a flaked tool. Otherwise, the flakes will not flake off properly, or the flakes may be malformed and useless. The first criterion is the hardness of the raw material, and the second is how isotropic the material is. Essentially this means the piece (core) selected to make the flake should be hard and brittle to provide a sharp working edge and homogenous enough not to fracture into pieces when struck by the hammer stone (Figure 1).

Figure 1. Freehand knapping from Cotterell & Kamminga 1990

The most common raw materials in Australian archaeology suitable for flaked stone tools are quartz, quartzite, silcrete, chert, chalcedony and mudstone. Quartz and silcrete are abundant throughout the vast interior of Australia, and not surprisingly, many flaked artefacts are made from these two materials. Quartz is milky white, made up of many hexagonal crystals, and when struck, tends to fracture along internal faults, breaking into many pieces.

While this provides sharp shards useful for cutting, it is not a homogenous material, and it is difficult to predict the outcome. Silcrete is generally grey-brown, relatively coarse-grained, speckled throughout with quartz grains, and quite homogenous. This means a predictable outcome is possible, and a proficient knapper can control the design of the flake.

Chert and chalcedony are in various colours, both homogenous and fine-grained in texture. An experienced knapper can control the design of the flake, resulting in a hardwearing functional tool. On a regional scale, other siliceous raw materials are found locally, such as obsidian, tektites and Darwin glass.

Figure 2. Silcrete outcrop in Western Queensland. Ewings 2002

Obsidian is found in northern Australia and was traded over long distances. Flakes from obsidian were highly valued and renowned for an extremely fine cutting edge. Tektite nodules originate from meteorite showers and are generally only found in small quantities. Small fragments of Darwin glass are scattered over a localised area in southern Tasmania, originating from the impact of a single meteorite.

A knapper must decide which raw material to use in manufacturing a flake. Often this is dictated by the proximity, availability and suitability of the material to the task. Most raw materials are sourced from outcrops in hills, ranges, or large pebbles along river courses.

Silcrete is abundant throughout the arid region, the remnants of Tertiary duricrust, now eroded into boulders of various sizes. The silcrete boulder pictured below (Figure 2) is from the Merton Escarpment in western Queensland. The boulder has been broken apart, creating smaller manageable pieces, and a suitable piece would be selected to serve as a core. A discarded flake is shown in the inset, possibly due to knapper sampling.

Grindstones

Figure 3. Grindstone (sandstone) Ewings 2002

Most grinding stones in Australian archaeology are sandstone slabs (Figure 3), often rounded at the edges for easy handling. Seeds were placed on the grindstone, and another stone (muller) was used to grind seeds into flour. Sandstone is granular, relatively soft, containing quartz grains that provide sharp edges to shred the seeds. The surface of the grindstone is continually being renewed as grains are ground off the slab, exposing sharp edges. The resultant flour would have grains of quartz mixed in, contributing to a high rate of dental wear. The muller stone is generally a hard granite-like material, and after years of use, a muller develops a flat working surface and becomes polished. You can see how flat and polished a stone becomes in the broken muller below (Figure 4.).

Figure 4. Muller Stone (granite) Ewings 200

The grindstone picture above (Figure 3) was utilised in seed grinding; however, other grindstone uses have been observed in ethnoarchaeology. The services include; nut cracking, pounding meat, crushing ochre for pigment, and grinding plants for food. Some polished grindstone fragments were found at Cuddie Springs (lesson 4 Map 1), suggestive of seed grinding and are tentatively dated to 30 000 BP.

However, evidence for the widespread use of seed grinding in Australian archaeology only dates to the Holocene. At Malakunanja II, an ochre-stained grindstone fragment, dating to 18 000 BP, was excavated, confirming the Pleistocene use of grindstones for ochre preparation. Ochre was ground to provide pigments for rock art and body decorations.

Hatchets

Figure 5.1 Edge ground hatchet

Some of Australia’s earliest dated stone artefacts are edge ground hatchet heads. Whilst some people refer to these artefacts as axes, the size and weight mean they were used with one hand like a hatchet and not two hands like contemporary axes. Figure 5.1 shows a waisted edge ground hatchet head excavated from Nawamoyn rock shelter dating back 20 thousand years. The similarity is striking to a hatchet head from the 1900s made in southern Australia (Figure 5.2)

Figure 5.2 Hatchet (greenstone) AD 1900s

Other hatchet heads older than 40 000 BP have been excavated from the Huon of New Guinea and ca 32 00 BP in Queensland. Hatchet heads appear early in the archaeological record throughout northern Australia. However, they are found in southern Australia in the mid-late Holocene. The waisted part of the hatchet head is the ground groove (Fig 5.1), enabling it to be hafted onto a handle as seen in the AD 1900s example. The cutting edges were shaped and ground on large sandstone blocks like the one below. (Figure 6).

Figure 6. Grooves in sandstone from grinding hatchets. from Mulvanney & Kamminga 1999

Australian Archaeology Flake Manufacture

Figure 7.1 Minnie Creek Rockhole, West Australia

Before we begin on the techniques and mechanics of flake production, a small side note on where stone flakes are found, many flakes (billions Australia-wide) are located on the surface, called background lithic scatters. These can be isolated flakes discarded after usage or lost while travelling. Often larger scatters indicate places where people camped, and these lithic scatters are around waterholes, along rivers or other obvious watering points (Fig 7.1).

Figure 7.2 Osborne Mine, Queensland

In other places, knapping floors (where people knapped flakes) occur in what appears to be unlikely surroundings. For instance, Figure 7.2 shows an exposed campsite that is perhaps thousands of years old. Whilst it initially appears an unlikely camp area, it is within a few kilometres of an extensive quarry where high-quality raw materials were quarried to make stone artefacts. The small flags dotted through Figure 6.2 denote the position of surveyed flakes.

Figure 7.3 Yamarna Rockshelter, West Australia

Flakes found in stratigraphic sequences within a rock shelter (Fig 7.3) provide a better opportunity to date a site securely. This is because a rock shelter offers less chance of disturbance than does an open-air site, permitting artefacts to remain in situ while the sands of time slowly cover the deposit.

Naming the Parts

Whilst working in Australia s arid region and conducting archaeology ecotours, one of the first things people asked was, how do you know this is a flake? Firstly, to identify a knapped flake or a core stone, you must know what to look for and be able to isolate specific features. Therefore, these features need a name, so let s start with the illustration, Figure 8.

Figure 8. Flake and Core attributes modified Davidson, 2001

1. The point where the flake is struck with the hammer stone is called the point of force application or PFA.
2. The top part of the flake, where it is struck off the core, is the proximal end. (The distal end is the bottom of the flake, where it terminates.

Figure 9. Flake, with a step termination

3. As mechanical force radiates down from the PFA, it creates a very distinctive bulb of percussion. Look at the bulb of percussion on the proximal end of the flake in Figure 9. A flake with a bulb of percussion is called a conchoidal flake.
4. The ring crack is the tiny protruding circle above the bulb.
5. Undulations are often seen on the ventral surface (surface inside the core before flaking). They are formed as mechanical energy travels down, striking irregularities in the core and causing the downward force to deviate slightly.
6. Looking at the Core in illustration 8, you will notice the reverse shape of the flake. The overall reverse shape of the flake in the core is referred to as a negative scar.
7. Also, notice the negative bulb of percussion.

Figure 10. Chert core Ewings, 2003

In Figure 10, the relatively large core stone still has some cortex attached or outside rind on the core. In this case, the core has been discarded as the core is considered exhausted, and the knapper has decided no more flakes could be struck off.

The core was found within a few kilometres of a chert outcrop, and no doubt a better piece could easily be acquired. However, in other areas where this high-quality raw material is less readily available, heavily reduced cores are more likely to be found. Studies have shown a correlation between core sizes and distance to raw material.

Many core stones are one-tenth this size, presenting no cortex, with every possible flake removed. Sometimes a core is found along with flakes and other debitage, constituting a knapping floor. It is possible to refit the flakes; a process called conjoining gives insight into the reduction sequence. By studying a reduction sequence, archaeologists can retrace the steps of an ancient knapper, understanding their approach to stone tool manufacture.

The method of flake manufacture referred to so far is primarily one of freehand knapping. Freehand knapping is the earliest known method of flaking, a practice dating back 2 million years ago to the Oldowan Industry of Africa. In Australia and other parts of the world, many more methods developed over time, such as; indirect percussion, bipolar, pressure flaking (see Kimberly Point Figure 11), chimbling and anvil techniques. Here is a brief outline of each method described by Professor Iain Davidson (2001).

Bipolar reduction: If a core becomes so small that contact with the hammerstone results in the core moving rather than detachment of a flake, its reduction can be continued by bipolar reduction. Bipolar is also a useful technique for knapping rounded pebbles, which were either too small or did not present angles suitable for freehand percussion. In bipolar reduction, the core is placed on an anvil, generally with its longest axis perpendicular to the anvil. The core is then struck at an angle of 90 degrees. The Term bipolar is derived from the fact that each core reduced by this method will have two polarised (directly opposite)striking platforms or zones of percussion (Binford 1972b:356). One of these zones is the point where the hammerstone comes into contact with the core; the other is formed by the core coming into contact with the anvil.

Indirect percussion: Indirect percussion involved using an intermediate percussor, such as a piece of stone with a rounded point, bone, wood or antler, between the hammer stone and the core. Indirect percussion is often termed the punch technique. The flakes are removed by indirect percussion and frequently have tiny platforms.

Pressure flaking: When the knapper requires precise control over the location of flake removal, size, and shape, this was achieved by pressure flaking. In the pressure flaking technique, a pointed instrument of stone, copper, bone, wood, or antler was used to exert pressure to push the flakes from the implement being produced. In Australia, Aboriginal groups still undertake pressure flaking this century.

The Rolling Pressure Technique: In the rolling pressure technique, the flake is held in the palm with the ventral surface uppermost and the edge to be worked resting on the pad at the base of the thumb. A rounded, generally smooth flat pebble is laid on the bulbar surface, rolled towards the margin and exerted pressure. This removed tiny, semi-circular, equal-sized flakes.

The Chimbling Pressure Technique: Chimbling was first described by Dickson (1973:12-13) as a method to retouch the edge of blades or flakes to produce Bondi Points. In chimbling, the flake is not held in hand but placed on a piece of bark or wood, which will give a little under pressure. This allows the full force of the arm to be used to remove the flake rather than just the fingers, as in the rolling technique discussed above.

Anvil Technique: In the anvil technique, the core is brought down directly on the anvil with enough force to initiate fracture. The result of this action will depend on the type and size of the core and the amount of pressure with which it contacts the anvil.

Larger pieces of raw material can be reduced by throwing them down on the anvil. This is quite a useful technique for producing smaller cores, which may be reduced by one of the standard techniques discussed above.

Figure 11. Kimberley Point, a bifacially flaked point

Stone tool manufacturing is a large field, and we have only touched on the subject. Many artefacts are only found in specific regions within certain time frames (e.g. Tula adze in the arid region), sequence and distribution.

References

Davidson, I. 2001, Archaeology of Stone Artefacts: Background notes, Archaeology and Palaeoanthropology, School of Human and Environmental Studies, University of New England, Armidale, Australia.
Flood, J. 1997, Rock Art of the Dreamtime, Angus & Robertson, Australia.
Lourandos, H. 1997, Continent of Hunter-Gatherers, Cambridge Uni Press, United Kingdom.
Morwood, M. 2002, Visions from the Past: The Archaeology of Australian Aboriginal Art, Allen & Unwin, Australia.
Mulvaney, J. & Kamminga J. 1999, Prehistory of Australia, Allen and Unwin, Australia.