Hammerstone

In archaeology, a hammerstone is a hard cobble
used to strike off lithic flakes from a lump of tool stone during the process of lithic reduction. The hammerstone is a rather universal stone tool which appeared early in most regions of the world including Europe, India and North America. This technology was of major importance to prehistoric cultures before the development of metalworking.

Materials

A hammerstone is made of a material such as sandstone, limestone or quartzite, is often ovoid in shape, and develops telltale battering marks on one or both ends. In archaeological recovery, hammerstones are often found in association with other stone tool artifacts, debitage and/or objects of the hammer such as ore. The modern use of hammerstones is now mostly limited to flintknappers and others who wish to develop a better understanding of how stone tools were made.

Usage

Hammerstones are or were used to produce flakes and hand axes as well as more specialist tools from materials such as flint and chert. They were applied to the edges of such stones so that the impact forces caused brittle fractures, and loss of flakes for example. They were also widely used to reduce the bulk of other hard stones such as jade, jadeite and hornstone to make polished stone tools. A good example is the hornstone found in the English Lake District used to make polished axes during the early Neolithic period, and known as the Langdale axe industry.
Hammerstones were used widely in crushing mineral ores such as malachite during the Chalcolithic period, the earliest part of the Bronze Age, and cassiterite prior to smelting of tin. Iron ores would have been crushed to powder in a similar way during the Iron Age. Such crushing was needed to hasten and encourage reduction in the furnaces where charcoal was the main reducing agent.
Other examples of their use include reducing minerals like haematite to powder, for pigment, and crushing of hard nuts, such as hazel nuts, to extract the edible kernels.

Types of hammerstone

Throughout the period of time in which humans have made stone tools, different techniques and different types of hammerstone have been used. The following are the basic types; Certain sophisticated procedures requires more specialized tools.

Direct percussion

Sleeping (passive) hammer

A large stone set in the ground or firmly mounted. The stone being worked is hit against this anvil, resulting in large flakes that are further processed into tools. This technique is not well known, though there is evidence of it being used during the Lower Paleolithic. The problem with the anvil stone is that the user handles large stones, which can be difficult to control with precision.
Another way of using the sleeping hammer as an anvil is more typical of advanced periods. Although it is based on the use of an anchored stone, the technical concept is completely different: it is about resting stone chips or sheets on the anvil and carrying out an abrupt retouching due to impact on one side or extremity thus obtaining retouched orthogonal fractures. It is also possible to retouch stone tools on the anvil by means of pressure flaking, thus obtaining a regular and monofacial retouched edge.

Active hard hammer

A simple stone with a worked edge held directly in the hand as a hammer. The hard hammer is and has been the most used throughout human history, because although other types of hammer are used as main tools for carving, stone hammers are the tools that prepared the way for the more advanced techniques. Hard percussion is the first to appear and the only one known for at least two million years ; it was used to manufacture tools throughout the entire operational sequence until lithic technology improved. Then, the hard hammer was relegated to the first stages of making an artifact: the initial roughing, the primary workmanship, the attack of percussion planes inaccessible to the soft hammer, the preparation of percussion platforms in certain nuclei, etc.
Despite indirect evidence of its long persistence, archeology has revealed very few hammers. Among the oldest are those cited by Jean and Nicole Chavaillon in both Gomboré 1B, Melka Kunturé and even Olduvai : Active hard hammers are distinguished by their oblong shape with one or two active edges with numerous shock marks and often small flakes, as well as some cracks. These are recognized by the numerous traces of blows they have.
It is possible that in the old and unsystematic excavations they went unnoticed, but it has also been said that the good stone hammers were so appreciated that the craftsman only abandoned them when they were useless. Semenov speaks of a deposit rich in hammering, but, like the rest of the sites, they are almost all from the Neolithic period onwards. The size of hard hammers depends on their function: there are very large ones for roughing, medium ones are used for the main work, small ones are auxiliary tools to prepare percussion platforms, or retouch flakes. As for the shape, there are circular, oval, rectangular, etc... In fact, the shape depends a lot on the style of the craftsman.
Despite the fact that stone hammers are more typical of the manufacture of wide and short flakes, used with mastery they can achieve very precise control of rock chipping. In fact, cases of blades manufacture with a hard hammer have been witnessed, mainly in the Middle European Paleolithic, but also in the Upper and Epipaleolithic. While the extraction of blades is more effective with other techniques, there are enough indications to affirm that it can also be done with a hard hammer. There are even exceptional cases of obsidian blade of more than 30 centimeters manufactured in pre-Columbian Mexico and ancient Ethiopia and greater examples in excess of 70 centimeters found in present-day California. Modern experimental carvers have not been able to recreate these methods.

Soft hammer

A soft hammer is a fragment of deer antler or hardwood that is used to hit the rock and extract flakes. Soft hammers are usually about 30 or 40 cm long and the ideal size to hold in the hand. The material from which they are made is very varied, since throughout their history humans have hunted many species of deer throughout the globe, but experimental carvers particularly appreciate those of reindeer or caribou. The bovine horn is not as suitable as the cervid antler, as it has an external keratin coating separate from the bone core, however they can be used as retouchers. In the case of wood, only especially hard species serve, such as boxwood, holly, and perhaps oak. In any case, the soft hammer wears out with its use relatively quickly. Each blow eats a little from the hammer. Wood hammers wear down especially fast. The antler hammers last a little longer, but in the end they break due to fatigue. Observation with the naked eye reveals that the flint leaves small splinters and stone chips embedded in the hammer.
In archaeological excavations, soft hammers are even rarer than hard ones, as they are organic and therefore perishable. François Bordes and Denise de Sonneville-Bordes exhumed one from the most recent Solutrean strata in the Laugerie-Haute cave. The piece was broken into several fragments and incomplete, but retained the functional end, where the marks of the blows could be seen and microscopic embedded flint bits were visible. The petrological analysis additionally determined that it was the same type of flint as the carved pieces extracted from the same archaeological layer.
Despite this brittleness, soft hammers have a series of advantages derived from their elasticity and resistance to stress-deformation. The soft hammer has a lower yield than the rock, that would make a layman think that it is impossible to carve flint or quartzite with a piece of wood or antler. However, its elastic limit is much higher, which makes it bear more tension and it is the rock that breaks, instead of the hammer. This does not happen, however, with the bone. Bone strikers are often unsuitable for carving, in fact bone is more of a carved raw material than rocks.
During the percussion itself, which lasts thousandths of a second, the soft hammer, being a non-isotropic linear elastic, varies its tension state and increases its internal energy in the form of elastic potential energy. The moment the rock reaches its elastic limit and breaks, the potential energy is released and the hammer returns to its original shape. Also due to its elasticity, the contact surface between hammer and rock is greater, since the hammer adapts to the percussion plane. The percussive area is larger, so the fracture is more diffuse than if one were to use a hard hammer, so the conchoid is also less pronounced. It is a process so fast that it is invisible to the human eye, but its consequences have been exploited for more than a million years. In practice, these elements give the craftsman greater control over carving, in easier-to-direct results, and in more precise and defined varnishing; in short, the carving is more efficient and its results more effective: Artifacts carved with a soft hammer have a much finer finish than those where only the hard hammer has been used.
The soft hammer appeared during the Lower Paleolithic, specifically in the Acheulean, 700,000 years ago in Africa and half a million years ago in Eurasia. However, the soft hammer does not replace the hard hammer, on the contrary, it complements it. Typically, the roughing or preparation of the piece is done with a hard hammer, and the finish with a soft hammer. Carved objects have scars from both types of hammer. Often the finished and used tools were recycled, re-sharpened, possibly with hard hammer, so there would be several alternate phases of hard and soft hammer. Other times, in the case of the cores, although the extraction of flakes or sheets was done with a soft or pressure hammer, the hard hammer was necessary to prepare the percussion platform and eliminate protrusions that could disrupt the operation.
The carving experiments of Professor Luis Benito del Rey, tenured professor of Prehistory at the University of Salamanca, serve to distinguish, with a certain degree of acceptable precision, carving scars by direct percussion with a hard hammer. and those of the soft hammer compared to each other.

Direct percussion with a hard hammer	Direct percussion with a soft hammer

Generates thick pieces, with irregular edges and slightly sharp edges	Generates thinner and more regular pieces, with much sharper edges
Seen in profile, the edges are sinuous because the negatives of the flakes are marked and quite deep	The edge, seen in profile, is relatively rectilinear or a little wavy, but without marked irregularities
Sometimes, the sinuosities produced by the more marked counter-conchoids can be rectified by a detailing tool or hard hammer; in this way, the profile edge is zigzagging	The counter-conchoids are diffuse and shallow, which does not prevent the edge from being often refined with a much more careful detail that, in fact, reinforces the edge
The marks left by the flakes extracted by means of direct carving with a hard hammer are larger and less numerous	The flakes of the direct soft hammer are longer than they are wide, invasive, shallow, and sometimes less than a millimeter thick
The flakes obtained by this procedure are wider than they are long, and they are narrower in the proximal than in the distal part, with a thick heel and a very marked percussion cone and conchoid. The veins that separate the flakes from each other are easy to see.	It is difficult to distinguish the veins that separate the flakes from the soft percussion because their edges are extremely thin and overlap imprecisely. The flakes have edges so fine that they are translucent. Their heel is linear or pointed and sometimes they have a cornice over the conchoid, instead of a percussion cone.
Whether the flakes are a by-product of the carving of a utensil, for example a hand axe, or if they are flakes extracted from a bifacial nucleus, there is no way to distinguish them, so there is no certainty as to whether they are waste.	The flakes of the carving or the retouching of utensils are, almost always, very characteristic by-products. Those extracted from nuclei prepared for the soft hammer, on the other hand, are specific flakes that would never be confused with carving debris.
When making bifaces by this technique, its section is polygonal, prismatic, quite irregular and asymmetrical.	The section of a bifacial artifact carved with a soft hammer tends to be lenticular, with very sharp angles.
The marks derived from direct percussion with an active hard hammer are impossible to discern from those obtained with a sleeping or passive hard hammer	The marks of a soft hammer usually overlap with other previous ones typical of the hard hammer, since it was common to start a piece with a hard hammer until obtaining an outline or preform, and finish it with a soft hammer.
The piece has a heavy, rough, primitive appearance, although such circumstance cannot be taken as a chronological or evolutionary indicator, since there are numerous circumstances that may have influenced it.	The result is an elegant, fairly regular, symmetrical, very well finished and more delicate looking artifact. These elements cannot be considered chronological features either.

The direct soft hammer was used throughout the Upper Paleolithic of Eurasia to obtain blades and flakes, by means of a specific preparation. Prehistoric carvers were able to obtain blades of over half a meter in length. Although the experiments have been able to recreate the methods used, they are still poorly known and the results are often subject to size accidents and fortuitous behavior of the material.