2015: Making an Island World: Neolithic Shetland. Felsite polished axeheads/adzes and Shetland...

North Roe Felsite Project

Report 2, January 2015

Making an Island World:

Neolithic Shetland

Felsite polished axeheads/adzes and

Shetland knives in Shetland Museum

– recording, characterization, and

interpretation of the collection

UCD School of Archaeology North Roe Felsite Project Report 2

www.ucd.ie/archaeology 2

METHODOLOGY

A database format for polished stone axeheads/adzes was then defined (Fig. 1), combining the attributes recorded by Nielsen (1977b) and Cooney & Mandal (1998).

Figure 1. Database format for the recording and characterization of felsite and other polished stone axeheads in Shetland Museum.

Figure 2. Database format for the recording and characterization of Shetland knives in Shetland Museum.



The Danish and the Irish axeheads/adzes differ considerably in morphological terms, with the former predominantly being four-sided and the latter two-sided. The basic principles followed by the two groups of analysts also differ substantially, with the former aiming to metrically quantify axehead attributes, whereas the latter aims to verbally/visually characterize the axehead/adze attributes by the application of pro forma descriptive categories.

At the time of recording, it was decided to assess which approach would prove most useful, as the application of predefined formal categories should be fastest, whereas the quantitative approach might allow the production of metrically based diagrams through which it should be possible to define formal and size-based axehead/adze types. For this reason, both sets of attributes were recorded and subsequently test which individual attributes and descriptive principles might prove most productive.

Attributes for the Shetland knife database format (Fig. 2) were selected/defined by the author in collaboration with Gabriel Cooney (University College Dublin) during inspection of the felsite axeheads/adzes and knives in National Museums Scotland in 2012.

Axehead/adze attributes, general

The first group of fields in the axehead/adze database form (Fig. 1) relates to the individual identification of the pieces, such as unique catalogue number, museum, museum reference number, site, parish, national grid reference (NGR) and main axehead/adze type (ie, whether the individual piece is an axehead or an adze, an advanced rough-out, a partially polished specimen, possibly not an axehead [for example in cases where a piece has originally been erroneously classified in connection with museum accessioning], or uncertain). It was decided to exclude early-stage axehead rough-outs, as they are usually not

morphologically definable in the same manner as finished axeheads/adzes are (due to their incomplete state), and they are almost exclusively found within the North Roe quarry areas.

The following group of fields deals with the characterization of the raw material of the individual axeheads/adzes, and it was chosen to only refer the implements to a small number of general raw material types which would be relatively easily recognizable when dealing with hand specimens.

The defined raw material categories are:

Very dark with pink and/or white feldspar crystals

Very dark with small quartz prisms and elongated feldspar crystals

With small spherulites (<2mm)

With medium spherulites (2-5mm)

With large spherulites (5-15mm)

With very large spherulites (>15mm)

With parallel bands

With wavy bands

Homogeneous/no patterning

Some pieces are characterized by combinations of the above raw material attributes (for example including spherulites as well as banding). Another database field describes the axeheads’/adzes’ main (original) colour (black; dark blue, blue/white; blue/green; green; dove-grey; and uncertain), whereas secondary colours (due to weathering, peat bleaching, etc.) are defined in a separate field (white; brown; slightly faded; none).

Axehead/adze attributes (Nielsen 1977b)

Nielsen’s attributes are all quantified expressions. The primary axehead/adze attributes applied by Nielsen (1977b) are identified in Fig. 3, and they cover: 1) length; 2) width of butt (measured 2 cm from the end); 3) thickness of butt (measured 2 cm from the end); 4) greatest thickness; 5) distance from butt to greatest thickness; 6)

Figure 3. The nine primary proportions of a Danish

Neolithic axehead/adze (Nielsen 1977b, 11).

Axes and knives from the collections at the Shetland Muse-

um (Photo courtesy of Jenny Murray, Shetland Museum).



width of lateral sides at the point of greatest thickness; 7) width of edge; 8); greatest width (not incl. in Nielsen’s original system); 9) curvature of the edge (radius of the circle defined by the curved edge); and 10) angle of the lateral sides.

Greatest width was not included in Nielsen’s original system, as the greatest width of a Danish Neolithic polished flint axehead/adze almost always corresponds to its edge width. This attribute was added to the system to allow it to cover the Shetland axeheads/adzes, where the broadest point of the implement tends to be somewhere between the edge and the butt, usually near the object’s centre. It was decided to measure the curvature of the edge in a simpler manner than that suggested by Nielsen, and instead of measuring this feature as the radius of the circle defined by the curved edge, it was measured as the depth of the edge as a percentage (ratio) of the width of the edge (Fig. 4) – following this approach, the ratio of a highly curved edge would approach 50%, whereas an almost straight edge would approach 0%.

Due to the frequently convex lateral sides of the commonly ovate Shetland axeheads/adzes, it was occasionally difficult to measure the angle of the lateral sides, and these measurements should be perceived as approximations. It was also frequently difficult to measure the width of the edge (and as a consequence also the curvature of the edge), if the edge was not

clearly demarcated against the lateral sides through the presence of more or less pronounced cutting-edge corners/junctions. The measurement of these attributes are therefore also occasionally approximations.

In addition to these primary ‘proportional elements’, Nielsen also recorded a number of secondary and tertiary elements, namely: 11) the butt index (thickness of the butt as percentage of the width of the butt); 12) the distance from the implement’s butt to its greatest thickness in per cent of total length (Fig. 5); and 12) broadside (face) convexity. Nielsen defined broadside convexity as the difference between greatest thickness and the width of the lateral facets as a percentage of greatest thickness, but as most of the Shetland axeheads/adzes are two-sided pieces

without lateral facets, it was chosen instead to measure this attribute in a manner similar to that applied to measure the curvature of the cutting-edge: depth of face (greatest thickness : 2) as a percentage of greatest thickness (Fig. 6).

Axehead/adze attributes (Cooney & Mandal 1998)

Figure 4. The measurement of the curvature of the axeheads’ cutting-edges, ie. the depth of the edge as a percentage (ratio) of the width of the edge.

Figure 5. The distance from the butt to the greatest thickness in per cent of total length.



The choices presented in the raw material and colour fields correspond to the choices given in the axehead/adze form’s raw material and colour fields.

The form’s ‘Individual formal elements ’ section describe 1) whether (or to which degree) the individual face is flat, convex, or concave; 2) whether the individual blank could be identified as a core (dorsal/dorsal faces) or a flake (ventral/dorsal faces); 3) whether the individual piece is single - or double-edged; 4) the delineation of the individual cutting -edge (Delin 1) and back (Delin 2); 5) the delineation of the individual end; 6) and whether the individual piece has corners, and if so, the character of these corners.

The following section deals with fragmentation and secondary modification of cutting -edges and backs, as well as with the question as to whether the individual knife may have been rejuvenated, repaired or recycled. The final section presents the three main dimensions of the knives, as well as their weights, followed by a general comments field for any relevant characterization not covered by the sections and fields listed above.

AXEHEADS/ADZES AND SHETLAND KNIVES – THE CHOICE OF RAW MATERIAL

Where the axeheads/adzes and knives differ fundamentally in terms of function (chopping vs cutting) and, as a consequence, morphology, they share one attribute – both implement forms were predominantly manufactured in North Roe felsite. However, a choice seems to have been made as to which specific type of felsite was selected for each implement form and it was the author’s impression (eg, Ballin 2011d; 2011b) that axeheads/adzes were mainly made in relatively plain felsite, whereas the knives were made in more highly coloured and patterned felsite.

Tables 1-3 were produced in an attempt to test this impression. Table 1 gives an overview of the many different types of raw material used to manufacture the Shetland axeheads/adzes and knives; Table 2 is a summary of Table 1, showing the four main categories of raw material (non-spherulitic and spherulitic felsite; serpentinite; and other raw materials); and Table 3 shows the relative proportions of non-spherulitic and spherulitic felsite.

Table 2 demonstrates how the Shetland stone axeheads/adzes are mainly based on felsite (74.1%), with 12.6% of the axeheads/adzes being in serpentinite and 13.3% in other raw materials. The Shetland knives include a considerably larger proportion of felsite (95%), with no knives being in serpentinite, but with 5% of the knives probably being based on other raw materials. Table 3 confirms the impression of felsite axeheads/adzes being fairly plain and knives more spectacular – where the felsite knives are distributed almost evenly across non-spherulitic and spherulitic felsite, the vast majority (85%) of the felsite axeheads/adzes are non-spherulitic.

This impression is further confirmed by Table 1, which shows that where spherulitic felsite axeheads/adzes are mainly based on felsite with small spherulites, the spherulitic knives include considerably higher numbers of pieces with larger and more spectacular spherulites and/or with notable banding. Although Table 1 confirms the impression that spherulitic felsite was rarely used for axeheads/adzes, approximately one-tenth of the felsite axeheads/adzes are characterized by banding.

The selection of different types of raw material/felsite for the two implement forms probably mainly relates to the different functions of the axeheads/adzes and knives. As both implement forms probably include pieces intended for everyday use as well as for use as ceremonial/prestige objects, both forms should be expected to include plain as well as more spectacular specimens. However, the axeheads/adzes and knives were used differently in mechanical terms, with the former mainly processing hard materials in a chopping mode, whereas the latter mainly processed softer materials (although it is presently uncertain exactly which) in a cutting mode. For axeheads/adzes this probably meant that any decorative effects could represent weaknesses, and during chopping the axeheads/adzes would be most likely to break along the banding, or along the edges of large spherulites. Hence a plain axehead/adze is probably considerably stronger and more durable than a decorative one.

Figure 6. The measurement of broadside convexity, ie. the depth of one face (greatest thickness : 2) as a percentage (ratio) of greatest thickness.



Quantity Per cent

Group Raw material Polished

axeheads and adzes

Shetland knives

Total Polished

axeheads and adzes

Shetland knives

Total

1

Homogeneous/no patterning, or faint banding or a few inclusions

19 2 21 15 3.3 11.2

Small quartz prisms and elongated feldspar crystals 15 10 25 11.8 16.7 13.4

Small quartz prisms and elongated feldspar crystals/some banding

3 1 4 2.4 1.7 2.1

V. dark w pink or white feldspar crystals 21 5 26 16.5 8.3 13.9

V. dark w pink or white feldspar crystals/some banding or quartz

7 5 12 5.5 8.3 6.4

Parallel or wavy banding 15 3 18 11.8 5 9.7

2

Small spherulites (<2mm) 2 2 4 1.6 3.3 2.1

Small spherulites (<2mm)/some banding or inclu-sions

6 8 14 4.7 13.3 7.5

Medium spherulites (-5mm) 3 1 4 2.4 1.7 2.1

Medium spherulites (-5mm)/some banding or inclu-sions

1 5 6 0.8 8.3 3.2

Large spherulites (-15mm)/occasionally some band-ing

7 7 11.7 3.8

V. large spherulites (-25mm)/occasionally some banding

2 4 6 1.6 6.7 3.2

V. large spherulites (-50mm)/occasionally some banding

4 4 6.7 2.1

3 Serpentinite 13 13 10.2 7

Possibly serpentinite 3 3 2.4 1.6

4 Most likely not felsite or serpentinite 16 2 18 12.5 3.3 9.6

Uncertain 1 1 2 0.8 1.7 1.1

TOTAL 127 60 187 100 100 100

Table 1. The different raw materials selected for the production of axeheads/adzes and Shetland knives.

Quantity Percent


axeheads and adzes

Shetland knives

Total Polished

axeheads and adzes

Shetland knives

Total

1 Non-spherulitic felsites 80 26 106 63 43.3 56.7

2 Spherulitic felsites 14 31 45 11.1 51.7 24

3 Serpentinite 16 16 12.6 8.6

4 Non-felsite/-serpentinite or uncertain 17 3 20 13.3 5 10.7

TOTAL 127 60 187 100 100 100

Table 2. The different raw materials selected for the production of axeheads/adzes and Shetland knives – non-spherulitic/

spherulitic felsites, serpentinite, and other raw materials.

Quantity Percent


axeheads and adzes

Shetland knives

Total Polished

axeheads and adzes

Shetland knives

Total

1 Non-spherulitic felsites 80 26 106 85.1 45.6 70.2

2 Spherulitic felsites 14 31 45 14.9 54.4 29.8

TOTAL 94 57 151 100 100 100

Table 3. The different raw materials selected for the production of axeheads/adzes and Shetland knives – the main types of

felsite.



CHARACTERIZATION OF THE AXEHEADS/ADZES

Fragmentation and main dimensions of intact pieces

As shown in Table 4, almost 70% of the axeheads/adzes in Shetland Museum are intact, with the remainder representing various forms of butt, medial, and edge fragments.

The main dimensions were calculated for the three most important axehead/adze categories (intact and chipped pieces), namely axeheads (42 pieces), adzes (40 pieces) and advanced rough-outs (4 pieces). The axeheads and adzes have roughly the same average dimensions, with the former having mean values of 166 x 63 x 34mm and the latter 170mm x 63 x 29mm. Rough-outs ought to be slightly larger than finished specimens, as they still need to be reduced somewhat to obtain their final shape and then to be polished. This may be reflected by the average dimensions of the four intact advanced rough-outs examined in the museum stores (av. dim.: 238 x 80 x 51mm), which are roughly 70mm longer than the polished axeheads and adzes. The two rough-outs from the Grut Wells hoard (see forthcoming report by Ballin & Topping 2015) have lengths of 421mm and 306mm, defining them as unusually large and ‘special’ pieces. The serpentinite axeheads/adzes form a separate group of generally small pieces, with intact specimens (safely identified as serpentinite) measuring on average 82 x 41 x 19mm.

General typology

An overview (Table 5) of axehead/adze typology was produced by combining information in Fig. 1’s ‘Main axe type’ field, the ISAP ‘Butt shape field’, and notes in the form’s ‘Comments’ field. Table 5 is based entirely on information stored in the former of these three database fields.

As shown in Table 5, 4% of the assemblage represents advanced rough-outs (ie, pieces which are well beyond what one might expect to find at the North Roe workshops, but not yet fully polished); 47% are axeheads; 43% are adzes;

and 6% are uncertain. Most adzes (25% of the total) have straight edges (seen from the front), whereas 14% have more or less hollow edges. One adze (1%) is an expedient piece (ARC 65267). ARC 66196 was defined as having a convex edge (1%), as the hollow of its cutting-edge is orientated towards the upper face of this asymmetrical adze, whereas pieces defined as hollow-edged adzes have the hollow of their cutting-edges orientated towards their lower faces.

The low number of recovered advanced rough-outs is

probably due to these pieces generally having been

transformed into finished axeheads/adzes by polish. It is

interesting to note, that one of these was found in Brae,

Delting parish (ARC 06810), and the other in South Setter,

Tingwall parish (ARC 07517), supporting the suggestion that

the transformation of ‘raw’ rough-outs (like those recovered

from the workshops in North Roe), through ‘advanced’

rough-outs, into finished axeheads/adzes, took place at sites

‘off the mountain’ and away from the felsite quarries (Ballin

2013).

Two pieces (ARC 00655, 65236) have twisted or oblique

edges (corresponding to 2%), which is usually a sign that the

adzes were reduced by following Reduction Method 3 in Fig.

7. Cursory examination of early-stage rough-outs from the

North Roe workshops suggests that, most likely, roughly

equal numbers of rough-outs were shaped following each of

the three different approaches, depending entirely on the

shape of the available felsite blocks and the presence or

absence of fault-planes. This means that, probably, a

considerably higher proportion than 2% of the assemblage

was reduced in this manner (not all adzes reduced by

adhering to Method 3 acquired twisted edges). This view is

supported by the location of the many unpolished flake

scars across the broadsides (below), which are frequently

positioned diagonally (pers comm. Brendan O’Neill). ARC

1991.403 has a distinctly rhomboid cross-section.

Quantity Per cent

Intact 80 64

Chipped 5 4

Corner of edge broken off 3 2

Butt broken off 13 11

Edge broken off 3 2

Edge half 5 4

Butt fragment 1 1

Medial fragment 3 2

Edge fragment 1 1

Various other damage 3 2

Recycled, reworked, re-used 9 7

TOTAL 126 100

Table 4. Fragmentation of all stone axeheads/adzes in

Shetland Museum.

An example of an axe roughout from Shetland Museum

(Photo by UCD)



The distinction between axeheads and adzes subdivides the assemblage functionally, but it is also possible to subdivide it in stylistic terms, for example according to cross-section and butt-shape. Practically all axeheads/adzes from Shetland are two-sided pieces with somewhat domed broadsides and, occasionally, discrete lateral facets, but a number of small serpentinite axeheads/adzes stand out, having flat broadsides/faces and square cross-sections.

Following Danish distinctions (eg, Vang Petersen 1993), the pieces were also subdivided according to a number of general butt shapes, such as, pointed-butted, thin-butted, round-butted and thick-butted. Most likely, felsite axeheads/adzes were generally made as pointed-butted implements, but in some cases these butts became slightly broader (approaching the thin-butted type), and in some cases they turned out slightly thicker (approaching the round-butted type) – or in other words, these three types probably represent a continuum. Only seven thick -butted axeheads stand out as a distinct other type. Most of these are very small serpentinite axeheads, with lengths between 60mm and 70mm.

Two other formal groups were defined, namely chisels and pieces with splayed edges. Two pieces (ARC 65241, 65457) were characterized as chisels (length = 129mm and 151mm) with narrow cutting-edges (edge-width = 39mm and 44mm). Although these two pieces stand out, due to their narrow cutting-edges, they are not numerous enough to be seen as a specific functional sub-type. In contrast, metric analysis of Danish polished axeheads from the Neolithic Single Grave Culture allowed the separation of axeheads into two distinct sub-types, namely traditional (larger) axeheads and chisel s(Højlund 1974, fig. 3).

A small group of pieces have splayed edges. Two of these (ARC 65226, 65554) are exceptional, very large axeheads (L = 275mm, 258mm), characterized by their splayed edges, as well as by their almost round cross-section and highly regular, all-over polished faces. These two pieces are most likely ceremonial or prestige objects. As ARC 65226 and ARC 65554 are almost morphologically identical, there is little doubt that they represent a stylistic type, but whether they represent a late type (formally inspired by splayed metal axeheads), as some analysts suggest, should probably be considered an as yet unresolved question. After all, this group still only includes two surface-collected pieces. It is also possible that they represent an idiosyncratic form – that is, they may have been manufactured by the same person for deposition together – but this interpretation is not supported by the find

Figure 8. The weight of all intact axeheads/adzes.

Types Quantity Per cent Main types

(%)

Advanced rough-outs 5 5 4

Axeheads 59 47 47

Adzes, expedient 1 1

43

Adzes w hollow edge 7 5

Adzes w slightly hollow edge

11 9

Adzes w convex edge 1 1

Adzes w straight edge 32 25

Adzes w twisted/oblique edge

2 2

Uncertain 8 6 6

TOTAL 126 100 100

Table 5. The distribution of axeheads/adzes across rough-

outs, axeheads and adzes.

Figure 7. Three different ways of transforming a felsite blank into a rough-out.

Example of a polished felsite axe from Shetland Museum

(Photo UCD)



locations of the two splayed axeheads: ARC 65226 was recovered from a field near Virdiefield, Dunrossness parish (southernmost Mainland Shetland), and ARC 65554 was found in Walls parish (West Mainland).

Figure 9 is a ‘raw’ diagram of the length and width of all

axeheads/adzes. The immediate impression given by this

diagram is that, if a small group of ‘outsiders’ towards the

diagram’s right side is disregarded, the main swarm of

points appears to cluster around a curving, rather than a

straight, trendline. This is discussed further below.

In Fig. 10, the undivided swarm of Fig. 9 has been

subdivided into a number of categories, including

advanced rough-outs, axeheads, adzes, and other forms. A

small group of very small axeheads/adzes towards the

lower end of Fig. 10 consists entirely of serpentinite

specimens, whereas rough-outs are generally found

towards the top of the diagram (still needing to be

reduced somewhat to gain their final form). Most

axeheads/adzes occur in the diagram’s central part,

where the two types overlap.

To explain the apparently curved nature of the swarm of

points in Fig. 9, the author experimented with a number of

different trendlines. In Fig. 11, two trendlines were inserted,

one taking the shape of a straight line and the other forming

an exponential curve. The latter is associated with a higher

correlation coefficient (R2) than the latter, supporting the

perceived curvilinear nature of Fig. 9’s point swarm (R2=0.60

and 0.64, respectively).

Figure 9. The length and width of all intact axeheads/adzes .

Figure 10. the length and width of advanced rough-outs

(green), axeheads (blue), adzes (red) and uncertain types

(black) adzes .

Figure 11. The length and width of all axeheads/adzes –

experiments with different forms of trendlines



The points were then split into axeheads and adzes, but

where the trendline of the axeheads maintained its

curvilinear shape and a high R2 (c. 0.7), that of the adzes

was less obviously curvilinear and characterized by a low R2

(c. 0.4). Is it possible that a higher proportion of the adzes

were produced for everyday use (ie, not for use as

ceremonial or prestige objects), and that their specific

shape was therefore less important?

Fig. 12 therefore only includes axeheads, and in this diagram large and small axeheads were separated into two groups, namely pieces larger and smaller than 175mm. The diagram shows that the impression of a curvilinear distribution may have been an illusion based on two axehead populations with different LW ratios, but with straight trendlines. The average LW ratio of the smaller axeheads is approximately 2:1, whereas that of the larger specimens is between 3:1 and 4:1. In other words, the smaller axeheads are relatively squat, robust pieces, whereas the larger ones are considerably more elegant, slender pieces. The division at L=175mm corresponds roughly to a division between pieces large and smaller than c. 600gr, and thereby supports the division by weight suggested by Fig. 8.

Width and thickness

The relative thickness (thickness-width ratio) of the axeheads/adzes from Shetland (Fig. 13) form a relatively loose linear cluster with well-defined directionality (R2 = 0.56). Apart from a poorly defined sub-cluster of small specimens (Th:W = c. 20:40mm) and some large outsiders, the points in Fig. 13 form one single cluster. The sub-cluster of small axeheads/adzes towards the diagram’s lower left corner are predominantly pieces made in serpentinite.

Width of edge

The felsite knappers of North Roe clearly made an effort to manufacture axeheads/adzes with a standardized edge-width. Fig. 14 has a clear main peak around edge-width 60-65mm ± 15mm. However, some pieces (for example functionally specialized pieces like chisels) have particularly narrow edges, whereas a small number of specimens (probably ceremonial/prestige pieces) have very broad

Figure 12. The separation of small and large axeheads and

the trendlines of the two clusters.

Figure 13. The width and thickness of all intact axeheads/

adzes.

A leached polished felsite adze from the Shetland Museum

(Photo UCD).



edges. A minor secondary peak around edge-width 40-45mm is dominated by 10 serpentinite axeheads/adzes and five pieces which are in other raw materials than felsite or serpentinite.

Cutting-edge corners (Junctions)

As shown in Table 6, c. 70% of all axeheads/adzes have obvious or discrete corners/junctions between cutting edge and sides, with the remainder either having none, or being uncertain.

It is possible that the axeheads/adzes were generally manufactured without cutting-edge corners, but gained

corners with use and repeated re-sharpening. To test this, the edge curvature was calculated for all axeheads/adzes with obvious corners and all pieces with no corners. Notably, axeheads/adzes without corners had almost twice as curved (deep) edges (curved edge ratio 33) as pieces with obvious corners, which had flatter edges (curved edge ratio 19).

Edge curvature

The curve produced in Fig. 15 is interesting, as it may (like Table 6) show the effects of use. The curve has a very broad, flattened peak between ratios 20-40, and as ‘factory-new’ pieces probably had a uniform, fairly convex edge (possibly with a curvature centred around ratio 33-35), the ‘flat-topped’ curve in Fig. 15 probably signifies varying degrees of

use. Through use, the originally symmetrical and convex edge became increasingly flat and occasionally asymmetrical.

Above, it was suggested that the development of corners may, to a degree, be linked to use, which also lowered the curvature of the edges. If this is indeed the case, intact, or almost, intact, larger axes (which may have been produced predominantly for use as ceremonial or prestige objects; Fig. 12) should generally be characterized by a more distinct edge curvature than smaller pieces. This turned out to be the case, with axeheads/adzes longer than 175mm having an average edge curvature of just below 30, whereas the average edge curvature of specimens smaller than 175mm is just above 20.

The recording of the shape of the edges, following ISAP’s

predefined edge shapes (Cooney & Mandal 1998, fig. 2.7)

showed that 9% of the specimens have slightly to notably

asymmetrical cutting-edges.

Broadside (face) convexity

Broadside convexity – that is, whether the axeheads/

adzes have more or less domed main faces – produced a

diagram (Fig. 16) which appears almost identical to Fig. 14.

The higher the broadside convexity ratio, the more domed

the broadsides. Fig. 16 shows that the axeheads/adzes

may be subdivided into two groups, namely pieces with

ratios centred around ratio 25-27 ± 3 (domed specimens),

whereas a small secondary peak is centred around ratio 16

-18 (flat specimens). Most serpentinite axeheads/adzes

are rather flat pieces, with a ratio between 12-25 (the

diagram’s secondary peak).

Angle of the lateral sides

As the initial diagram constructed to show the angles of

the axeheads’/adzes’ lateral sides was multi-peaked and

complex, a diagram was produced (Fig. 17) in which one

curve showed the angles of all axeheads and one the

angles of all adzes. This second diagram did not make the

situation less complex, but it did show interesting

differences between the general shapes of the two main

Figure 14. The edge-width of all intact axeheads/adzes.

Corners/Junctions Quantity Per cent

Obvious corners 36 30

Obvious/discrete corners 2 2

Discrete corners 43 36

Very discrete corners 2 2

No obvious/discrete corners 2 2

No obvious corners 26 22

Uncertain 8 6

TOTAL 119 100

Table 6. Presence/absence of cutting-edge corners. Only

pieces with intact cutting-edges are included

Figure 15. Edge curvature of all intact axeheads/adzes



implement categories, axeheads and adzes: both

categories have two main peaks – one with angles around

4-7 degrees and one with angles between 12-13 degrees.

The adzes then include a third group with angles around

16-17 degrees. The small group of axeheads and adzes

with angles between 22-25 degrees includes several pieces

in serpentinite which (see above) appear to form a distinct

separate group of axeheads/adzes.

It is not possible at present to determine whether the

three groups of axeheads/adzes represent pieces with

different dates or pieces with different functions.

Distance from butt to greatest thickness

The distance from the implements’ butt to their greatest thickness as a ratio of the total length is a measure of the weight distribution within the individual axeheads/adzes (Fig. 5). Fig. 18 shows that the axeheads generally have their thickest point near the middle or towards the edge (the axehead curve peaks at ratio 56-60), whereas the adzes form two sub-groups – one with the thickest point located slightly below the centre (ratio c. 41-45) and one with the thickest point slightly above the centre point (ratio c. 56-60) like the axeheads. The weight distribution within the implements may have had a bearing on function.

Polish

Lithics specialists frequently distinguish between grinding and polish, where the former is less smooth and commonly characterized by the presence of parallel striations from the grinding process, and the latter entirely smooth. In the present case, ground and polished pieces seem to form a continuum, with most pieces having striated, less smooth broadsides. As it was not possible to distinguish between the two forms of surface treatment in a meaningful manner, it was decided to refer to all ground or polished implements as polished. Only the small serpentinite axeheads are characterized by generally highly polished, mirror-like surfaces.

Most of the axeheads/adzes have all-over polish (85%), whereas 9% have partial or sporadic polish (Table 7). Approximately one-quarter of the all-over polished pieces have remaining unpolished flake scars (or flake scars which survive as polished hollows or ‘dimples’), which were simply too deep to be removed by grinding. Four per cent have edge-polish only, and 2% are entirely unpolished. The two unpolished pieces, as well as some of the edge-polished pieces, are almost finished, ready-to-polish rough-outs. In addition, some of the rough-outs were partially shaped by pecking, which has (so far) not been noted in connection with simpler rough-outs collected at the workshops in North Roe.

The ISAP attributes

Some of the sets of pro forma attributes used by the ISAP adds to the information provided by the metric characterization (above) of the axeheads/adzes in Shetland Museum, whereas others provide the same information, but in a different format. The ISAP attributes relating to edge shape, for example, overlaps almost entirely with the data provided by the measurements of edge curvature, although adding relevant information on the symmetry/asymmetry of the edges (touched upon above); and the ISAP attributes relating to butt shape overlaps with the definition of axehead typology presented combined in the form’s (Fig. 1) type field and comments field (above).

Figure 17. Angle of the lateral sides of all intact axeheads/

adzes: axeheads (blue), adzes (red).

Figure 16. The broadside convexity of all intact axeheads/adzes

Polish Quantity Per cent

All-over polish 108 85

Partial polish 10 8

Sporadic polish 1 1

Edge polish 5 4

Unpolished 2 2

TOTAL 126 100

Table 7. Presence and location of polish (all intact axe-

heads/adzes).



Face shape (outline of the axehead blade): As shown in Table 8, most of the museum’s axeheads/adzes are ovates (59%), with some having straight diverging lateral sides (13%), and some are asymmetrical (9%). The remainder includes a variation of other less common outlines.

Cross section: The information in Table 9 shows how the

Shetland axeheads/adzes differ from the Danish pieces

dealt with by Nielsen (1977a; 1977b). Where the Neolithic

Danish pieces are, as a rule, four-sided (cf. Vang Petersen

1993), the Shetland ones are more akin to the Irish pieces

dealt with by the ISAP (cf. Cooney & Mandal 1998), that is,

they generally have oval to pointed-oval cross-sections.

Probably around one-fifth of the collection has narrow,

relatively discrete side-facets (that is, without sharp edges

between the lateral facets and the broadsides), whereas the

vast majority of the pieces are two-sided axeheads/adzes

with the lateral seam where the broadsides meet being

rounded. A total of 12% of the pieces have plano-convex

cross-sections, identifying them as adzes.

Profile (section along long axis): The ISAP profile pro

formas include examples of symmetrical and asymmetrical

pieces, as well as examples of pieces with varying thickness.

The information on thickness overlaps with the metrical

information in Fig. 13, for which reason Table 10 was

simplified to only deal with the question of symmetry. Table

10 shows how the axeheads/adzes are distributed across

symmetrical/asymmetrical profiles at a ratio of c. 6:4. In

reality, axeheads and adzes are roughly equally common in

the collection (Table 5), but adzes were frequently defined

by other factors than their profile symmetry/asymmetry,

such as the character of the edge (it may for example be

hollow), or cross-section (eg, plano-convex).

Blade profile (section of cutting-edge and presence/

absence of cutting-edge facets): The ISAP blade profile pro

formas include examples of symmetrical and asymmetrical

pieces, as well as examples of pieces with unifacial and

bifacial edge facets. The information on symmetry/

asymmetry overlaps with the information presented in

Table 10, for which reason Table 8 was simplified to only

deal with edge facets. In Mahler (2010, 16), it is suggested

that the presence of edge facets indicates re-sharpening of

the axeheads/adzes, and thereby use, and it is noted that

such facets never occur on larger ceremonial or prestige

axeheads/adzes. As shown in Table 11, 18 pieces have edge

facets (14% of the total), and the vast majority of these

(83%) have unifacial facets.

Additional information

Only two pieces have longitudinal facets (ARC 65430, ARC

1990.218), and no implements appear to have been burnt. The

database form’s comments field was used to store information

which could not be fitted into any of the fields dealt with

above. These comments include notes on adaptation for use,

potential use, rejuvenation, repairs and recycling.

Adaptation for use includes preparation for hafting, which

mostly involves some flaking, chipping or pecking at the butt

end (eg, ARC 65303); as mentioned in Ballin (2013), axeheads/

adzes were usually polished first and then fitted into a shaft.

Actual axehead/adze use-wear is difficult to identify, but

Mahler (2010, 16) noticed gloss on some smaller pieces,

particularly at the edge (chopping) and near the butt (from

hafting) (possibly ARC 2001.126). Rejuvenation takes different

forms, but re-flaking (eg, ARC 65264) and re-polishing the

cutting-edge are the two main forms. Re-polishing the edge

would frequently result in the piece acquiring unifacial (most

common) or bifacial edge facets, as well as developing a more

distinct cutting-edge (edge facets and corners discussed in

separate sections above). Repairs are usually experienced in

connection with damage to butts and cutting-edge corners,

mostly in the form of flaking (eg, ARC 65452).

The most obvious signs of use are found on recycled specimens. The larger felsite axeheads/adzes were

Table 9. ISAP attributes: cross section.

Face shape Quantity Per cent

01 (ovate) 58 46

01/02; 01/03; 01/06; 01/? 16 13

02 (asymmetrical) 11 9

03 (straight diverging lateral sides) 14 11

03/04; 03/05; 03/06 3 2

04 (straight parallel lateral sides) 2 2

05 (oblique butt) 3 2

06 (other shapes) 19 15

TOTAL 126 100

Table 8. ISAP attributes: face shape (outline of the axehead

blade).

Cross section Quanti-

ty Per cent

01 (round/oval) 3 2

01/02; 01/05; 01/06 10 8

02/06; 02/15 (round/oval/discrete lateral 2 2

05 (oval) 10 8

05/06; 05/09; 05/13 33 26

06; 06/07; 06/10 (oval/discrete lateral 4 3

07; 07/11 (oval/lateral facets) 5 4

09 (flat oval) 11 9

09-Oct 7 5

10; 10/11 (flat oval/discrete lateral facets) 11 9

11; 12 (flat oval/lateral facets) 5 4

13 (pointed oval) 1 1

14 (flat pointed oval) 4 3

15 (irregular oval) 3 2

16 (plano-convex) 15 12

19 (indeterminate) 2 2

TOTAL 126 100



Profile Quantity Per cent

01; 02; 03 (symmetrical profiles) 71 56

Borderline profiles 7 6

04; 05; 06 (asymmetrical profiles) 43 34

7 (uncertain or fragmented) 5 4

TOTAL 126 100

Table 10. ISAP attributes: profile.

occasionally used secondarily as pounders, with their butts and, more rarely, their edges showing extensive crush-marks and rounding (eg, ARC 65453). On occasion, pieces were used more extensively, and the butt might have been used for pounding and the lateral sides for hammering (eg, ARC 65262). ARC 65543 has a pecked area at the centre of one broadside, suggesting use as an anvil. The bipolar

technique does not seem to have formed part of felsite reduction in general, but some large ‘bipolar cores’ have been recovered from the Grut Wells workshops, where they may have had a function other than producing small bipolar flakes (relating to the axehead production?).

The small serpentinite implements (more commonly axeheads than adzes) form a distinctive separate group, typologically as well as in terms of secondary use. As many as eight of 16 serpentinite pieces display signs of having been used secondarily as a pecking or pounding tool, with obvious rounding of butts and cutting-edges. ARC 65581 has had a deep groove cut into one lateral side, and may have been used as a line sinker.

Axeheads/adzes – summary

Although some polished axeheads/adzes from Shetland are in other raw materials than felsite (eg, basalt, gabbro, and schist), felsite was clearly the preferred raw material (almost three-quarters of the entire assemblage). Serpentinite pieces form the second most common group, making up 13% of all axeheads/adzes. Most of the felsite axeheads/adzes are in relatively plain forms of felsite, with a small number of these displaying discrete banding or small spherulites.

The axeheads/adzes were subdivided functionally and stylistically. Functionally, they were subdivided into advanced rough-outs (several characterized by a degree of polish or pre-polish pecking), axeheads, adzes, and uncertain pieces. The rough-outs are relatively uncommon (most were probably fully polished in prehistory). Axeheads and adzes are approximately equally numerous, with 47% of the category being axeheads and 43% adzes. Two axeheads with particularly narrow cutting-edges were defined as chisels.

In stylistic terms, the felsite specimens are generally pointed-butted pieces (or in the ISAP terminology: ovate forms), whereas the serpentinite specimens are mostly thick-butted pieces, supplemented by a small number of pointed-butted/ovate axeheads/adzes. Two almost identical pieces with splayed edges were recovered from contexts in Walls and in Dunrossness, but whether their unusual shape defines them as late (as suggested by some analysts), cannot be decided at the present time, as they are, after all, a very small statistical group associated with sparse contextual information.

Almost 70% of the axeheads/adzes are intact, with axeheads and adzes having roughly the same average dimensions, namely 168 x 63 x 32mm. The rough-outs are somewhat larger, as expected, as they need to be reduced further in connection with fine-trimming and polishing. Securely identified serpentinite specimens are considerably smaller, measuring on average 82 x 41 x 19mm. In terms of weight, c. 70% of the axeheads/adzes are relatively light (<600gr), whereas the remaining c. 30% weigh more than 600gr. Figure 8 indicates that the smaller pieces may form two groups, and it is possible that this split is caused by the presence of the diminutive serpentinite axeheads/adzes.

The analysis of the pieces’ length and width showed that, although some of the collection’s most spectacular specimens are indeed adzes, the adzes as a group are less strictly bound by formal demands than the axeheads, with the length:width of the pieces producing a fairly unimpressive correlation coefficient (R2) of only 0.4. More care was taken when the axeheads were manufactured with different forms of trendlines producing correlation coefficients of between 0.6 and 0.8. This probably suggests that more adzes than axeheads were intended for use, and that a higher proportion of the axeheads were intended to become ceremonial/prestige objects. The focus on the larger axeheads as ceremonial/prestige pieces is most clearly demonstrated by the fact that the smaller axeheads are characterized by a trendline with an R2 of 0.80 and an average L:W ratio of c. 2:1, whereas the larger ones are characterized by a trendline with an R2 of 0.64 and an average L:W ratio of (impressively!) between 3:1 and 4:1.

The width of the edge divides the axeheads/adzes into two groups, namely felsite pieces centred around an edge of roughly 60-65mm, whereas the serpentinite specimens generally have much narrower edges (c. 40-45mm). Approximately two-thirds of the axeheads/adzes have obvious or discrete corners where the cutting-edge and the lateral sides meet, but the fact that most pieces with corners have considerably flatter edges than those without corners indicates that most axeheads/adzes probably had no corners

Figure 18. Distance from butt to the point of greatest thick-

ness as percentage of total length (all intact axeheads/

adzes): axeheads (blue), adzes (red).



when they left the workshop. This is further confirmed by the fact that the diagrammatical curve (Fig. 15) describing edge-curvature is shaped like a ‘table mountain’ rather than a standard bell-shaped curve, with the ‘flat-topped’ character of the curve probably signifying varying degrees of use. Calculations of broadside convexity showed that the felsite axeheads/adzes generally have fairly domed broadsides, whereas the serpentinite pieces tend to be considerably flatter.

The angles of the lateral sides of the axeheads/adzes suggest the existence of possibly three formal sub-groups, namely axeheads/adzes with angles of 4-7 degrees and 12-13 degrees, and adzes with angles of 16-17 degrees. It is presently not possible to determine whether these groups are mainly chronological, functional or stylistic. Measurements of the distance from butt to greatest thickness produced one group of axeheads (peak at ratio 56-60) and two groups of adzes (peaks at ratios 41-45 and 56-60), respectively. It is thought that the weight distribution within the implements is likely to have a bearing on function.

The final element of the axehead/adze reduction process was polishing the objects. The vast majority of the pieces (85%) are polished all-over, with a small number of advanced rough-outs having no, or very little, polish. In addition, a group of axeheads/adzes have partial/sporadic polish or edge-polish, probably defining them as expedient pieces. Where most felsite axeheads display well-executed, but striated, broadsides (basically, what would usually be referred to as grinding rather than polish), many serpentinite pieces are characterized by high-gloss, mirror-like polish. This is unlikely to reflect on the different ways the two raw material groups were perceived in the past, as many of the low-gloss felsite pieces were produced as ceremonial/prestige objects, the

more high-gloss serpentinite pieces seem to be more generally functional pieces which were in many, if not most, cases recycled and used as ‘pecking tools’ (although it is presently uncertain exactly what they were used to peck).

Some of the ISAP attributes overlap entirely with individual quantified attributes, whereas others add additional aspects. Cross-section is an important ISAP attribute, as it shows quite clearly how the Shetland axeheads/adzes are mostly two-sided (with oval to pointed-oval cross-sections), and only approximately one-fifth of the pieces have narrow, relatively discrete side-facets. Pieces with plano-convex cross-sections were clearly intended to be used as adzes. The definition of the implements’ profiles (section along the long axis) also inform on function, with 56% being symmetrical pieces (probably axeheads) and 34% asymmetrical (probably adzes). A number of pieces have unifacial edge-facets, whereas others have bifacial edge-facets, probably indicating that these pieces were used and subsequently re-sharpened/re-polished.

Blade profile Quantity Per cent

Unifacial facets (01; 03; 05; 07) 15 83

Bifacial facets (02; 06; 09) 3 17

TOTAL 18 100

A substantial proportion of the axeheads/adzes display other signs of use-wear, informing on pre-use adaptation, actual use, rejuvenation, repair and recycling.

CHARACTERIZATION OF THE SHETLAND KNIVES

Fragmentation and main dimensions of intact pieces

As shown in Table 12, almost 80% of the Shetland knives are either intact or chipped, with the remainder representing various forms of end, edge, or medial fragments.

The main dimensions were calculated for the intact pieces of the five most distinct formal types of Shetland knives, namely 1) rectangular and sub-rectangular pieces (32 pieces); 2) oval and pointed-oval pieces (6 pieces); 3) drop-shaped pieces (4 pieces); 4) crescentic pieces (5 pieces); and 5) kidney-shaped pieces (2 pieces). The smallest and thinnest knives are the rectangular/sub-rectangular pieces (av. dim.: 146 x 98 x 7mm) and the oval/pointed-oval pieces (av. dim.: 157 x 105 x 8mm). The pieces belonging to the remaining three groups are all approximately twice as thick as those, with drop-shaped pieces measuring on average 160 x 89 x 14mm, crescentic pieces 173 x 95 x 15mm, and kidney-shaped pieces 244 x 131 x 14mm.

It should be borne in mind that these are average dimensions, and although some groups are dominated by thin or thick pieces, all five categories include delicate as well as more robust specimens. One sub-rectangular piece (ARC 1990.200) is only partially polished with undulating faces, and it is thought that this may be a half-finished rough-out or possibly an expedient specimen.

General typology

As noted above , it was possible to subdivide the knives into a number of formal types (Table 13), with sub-rectangular pieces being the most common type (54%), followed by oval/pointed-oval pieces (17%). Drop-shaped (7%) and crescentic pieces (13%) are characterized by having a point or rounded point at one end. Two kidney-shaped pieces form a heterogeneous group, with one piece

Table 13. The distribution of the Shetland knives across

formal types.

Outline Quantity Per cent

Rectangular 2 3

Sub-rectangular 18 30

Sub-rect., asymm. 11 19

Sub-rect./oval or drop 3 5

Oval 7 12

Pointed-oval 3 5

Drop-shaped 4 7

Crescentic 8 13

Kidney-shaped 2 3

Uncertain 2 3

TOTAL 60 100

Table 11. ISAP attributes: blade profile.



(ARC 65270) being roughly twice the size of the other (ARC 06583), and two rectangular pieces are both fairly irregular specimens (ARC 65281-2), which may owe their shapes to use and repeated re-sharpening. All knives from the Stourbrough Hill hoard are sub-rectangular or oval specimens.

As part of the typological assessment of the knives, the pieces were subdivided into two groups, namely those which are almost certainly based on flake-blanks, and those which are based on indeterminate blanks. A total of 42 knives were defines as being almost certainly based on flake-blanks. This assessment was based on a number of attributes, such as whether a specimen curved notably along one of its two main axes, or whether they were twisted along two axes or not. It turned out that some knives curved along one axis and others along the other, as shown in Fig. 19.

Seven knives, or 12%, were slightly twisted, which is a sign that these pieces were based on flakes which twisted along two axes, rather than curving along one (basically combining the two different forms of curvature shown in Fig. 19).

Weight

Figure 20 gives an impression of the distribution of intact Shetland knives across weight categories. Most of the knives form one concentration towards the diagram’s left side (101-175gr), indicating that most of these are relatively small. A number of small ‘bumps’ towards the diagram’s right side suggest that most larger pieces are individual specimens, and they do not form one well-defined category (this impression is supported in the following diagrams). The main concentration forms a number of small ‘sub-peaks’ and plateaux, which may suggest the existence of different categories.

One individual group of knives may have affected most of the diagrams and tables, namely the spectacular hoard from Stourbrough Hill on West Mainland, found and excavated by Dr Noel Fojut, Historic Scotland (Fojut forthcoming). With 19 almost complete pieces, this collection makes up just less of one-third of all the Shetland knives in Shetland Museum’s exhibitions and stores.

It is a well-known fact that some felsite knives were produced for everyday use (such as those from Modesty,

West Mainland; Sheridan 2012, fig. 2), whereas others were produced for ritual deposition (such as those from the Stourbrough Hill hoard). Fig. 20, as well as some of the following tables and diagrams, show that, most likely, separate production lines existed, with more delicate pieces being made for ritual use and deposition, and more robust pieces for everyday use.

Length and width

The existence of two separate categories of knives is clearly demonstrated in Fig. 21. The lengths and widths of knives from the Stourbrough Hill hoard form a linear cluster through the diagram, centred around a trendline with a fairly high correlation coefficient (X2 = 0.66), whereas all other probably mainly everyday knives have an extremely low correlation coefficient (X2 = 0.14), showing that their specific shape was of little consequence to the knappers, as long as the pieces had a useful cutting-edge.

Thickness

The thickness of the Shetland knives varies considerably – from 4mm to 24mm (Fig. 22). A difference of this magnitude must clearly indicate functional differences. Most pieces have a thickness between 4mm and 14mm. One highly distinct concentration of pieces with thicknesses between 4mm and 6mm stands out – the majority of these knives are pieces from the Stourbrough Hill hoard. Approximately half of the Storbourough knives have a thickness of 4mm, and the remainder 5mm. This supports the impression that well-executed, exceptionally thin pieces were produced specifically for ritual deposition.

The two faces

Most of the faces of the knives are flat, with flat/flat pieces making up more than half of the collection, and pieces with at least one flat face amount to almost four-fifth of the assemblage (Table 14). The second most common face shape is convex, with individual convex faces amounting to 28%. In addition there are small numbers of pieces with one or more concave or undulating faces. Six percent of the assemblage is made up of pieces with an undulating face, and it is thought that these pieces probably represent expedient knives, the faces of which were not

Figure 19. The bulbar position of the Shetland knives.

Figure 20. The weight of all intact Shetland knives.



polished as thoroughly as the better functional pieces, or the immaculate pieces which may have been produced for ritual use and deposition.

Single-/double-edged

Most of the knives have fairly thin edges, and at a first glance the pieces may generally seem to be double-edged implements. However, it is quite easy to feel with a finger whether an edge was intended to become a cutting-edge or a back (Table 15) – the cutting-edges have been polished quite sharp, whereas the backs have been neatly rounded by polish. A total of 90% of the knives have one edge, whereas 3% have two opposed edges (two crescentic pieces, ARC 65544, 65285), and 7% are indeterminate.

Although the cutting-edges are polished on either face, the actual final sharpening polish was generally carried out from one face only, resulting in cutting-edges with sections like that shown in Fig. 23. Occasionally, parts of the ends of the implements are also sharp, but this does not mean that the knives had additional terminal cutting-edges. The knives’ solitary cutting-edges simply have a tendency to continue a short stretch around the usually rounded corners of the pieces.

The two ends

The two ends, or terminals, are usually more or less convex (c. four-fifth), but in a small number of cases an end’s convexity is so slight that it appears straight (Table 16). Some of the drop-shaped and crescentic knives have either one or two pointed (sometimes rounded-pointed) ends. It is uncertain whether these latter types are intended forms or whether they may have reached their present form by repeated re-sharpening (re-flaking followed by re-polishing).

The delineation of the knives’ edges

The delineation of the the edges of the Shetland knives supports the identification of one edge (Delin 1) as a cutting-edge, and the other (Delin 2) as a back. As shown in Table 17, the cutting-edges tend to be slightly convex (53%), whereas the backs are more evenly distributed across a number of delineations, with a higher proportion of straight edges, or even concave or angled.

Figure 21. The length and width of all intact Shetland

knives.Red: The Stourbrough Hill hoard; blue: all other

knives.

Figure 22. The thickness of all intact Shetland knives

Face 1/Face 2 Quantity Per cent

Flat/flat 33 55

Flat/flat (twisted) 6 10

Flat/convex 9 15

Flat/convex (twisted) 1 2

Flat/concave 1 2

Flat/undulating 2 3

Convex/convex 4 6

Convex/concave 1 2

Convex/undulating 2 3

Concave/concave 1 2

TOTAL 60 100

Table 14. The faces of all Shetland knives.

An example of a typical felsite functional knife from Shet-

land Museum (Photo UCD)



Corners (Junctions)

The Shetland knives are generally fairly rounded forms, with most being sub-rectangular to oval – the form that would best describe that of most Shetland knives is the ‘super-ellipse’ as defined by the Danish artist-cum-philosopher Piet Hein (basically a hybrid between a rectangle and an oval; Fig. 24). The more this hybrid form approaches a rectangle, the more distinct corners the knife gets.

Table 18 shows the numbers of knives with and without corners. All corners of Shetland knives are more or less rounded, and the definition of this feature therefore involves a degree of subjectivity. Almost half of all knives (45%) have no corners at all, whereas 16% of the knives have a pointed end (drop-shaped and crescentic pieces) at one end and no corners at the other. A total of 14% of the implements have discrete corners, with one of these being a pointed specimen. Eighteen per cent of the implements have more obvious corners, and 7% are uncertain, mostly fragmented, specimens.

Secondary modification

As revealed by Table 19, half of the entire collection shows no signs of having been exposed to secondary modification. Approximately two-thirds of these pieces are made up of the 19 spectacular knives from the Stourbrough Hill hoard, which adds to the impression of Shetland knives embracing two production lines – delicate, well-executed pieces which may have been used for light work in special contexts, and which were subsequently ritually deposited, and more robust pieces for everyday use, which were rejuvenated, repaired, and finally discarded. A total of 6% of the Shetland knives have outlines indicating general re-working (e.g. the highly irregular rectangular specimens).

As many as 37% of the knives show signs of having had their cutting-edges rejuvenated – approximately two-thirds

of those have been re-sharpened by scale-flaking only, whereas c. one-third have been re-sharpened by polish (displaying a notable edge-facet), possibly after having first been scale-flaked. As described above, practically all cutting-edges were produced by final polish of one face only – in the same manner, they were re-sharpened unifacially, whether by the application of scale-flaking or polish. A total of 7% of the implements appear to have had their backs re-blunted, either by pecking, polish (displaying notable facets), or retouch.

Figure 23. Typical cutting-edge

of a polished Shetland knife.

No. edges Quantity Per cent

One edge/one back 54 90

Double-edged 2 3

Uncertain 4 7

TOTAL 60 100

Table 15. The distribution of all Shetland knives across

single- and double-edges forms.

Ends Quantity Per cent

Convex/convex 6 10

Convex/slightly convex 11 18

Convex/straight 3 5

Convex/pointed 6 10

Slightly convex/slightly convex 14 23

Slightly convex/straight 9 15

Straight/rounded point 1 2

Rounded point/rounded point 4 7

Uncertain/damaged 6 10

TOTAL 60 100

Table 16. The shape of the two ends of the Shetland knives.

Quantity Per cent

Delineation Delin 1 Delin 2 Delin 1 Delin 2

Convex 10 12 17 20

Slightly convex 32 16 53 26

Slightly convex to straight

12 15 20 25

Straight 5 9 8 15

Concave or slightly concave

4 7

Angled 1 2

Uncertain/damaged 1 3 2 5

TOTAL 60 60 100 100

Table 17. The delineation of the main cutting-edges (1) and

the backs/secondary cutting-edges of the Shetland knives.

One of the highly polished sub-rectangular ceremonial

knives from Stourbrough Hill on display in Shetland Muse-

um (Photo UCD)



Shetland knives – summary

As shown in Tables 1-3, the Shetland knives are almost exclusively in felsite (95%), with more than half of the felsite being spherulitic, highly patterned forms of this raw material. Following the distinctions made in connection with the characterization of the polished axeheads, only one knife may be an advanced rough-out, namely ARC 1990.200, which has one partially polished, undulating face. Being an unfinished piece, this specimen is also one of the collection’s heavier knives (539gr; cf. Fig. 20).

Most of the knives are sub-rectangular (54%) or oval (17%), and the fact that all the possibly made-for-deposition knives from the Stourbrough Hill hoard are either sub-rectangular or oval, it is thought that probably all new Shetland knives had these shapes, and that alternative shapes may generally be the result of use/wear and re-sharpening. More than two-thirds of the knives are certainly based on flake blanks, and it is suggested that flake blanks were preferred to naturally split felsite slabs.

Approximately four-fifths of the pieces are intact or chipped, with sub-rectangular and oval pieces being slightly smaller and more delicate than the remaining formal categories. They measure on average 150 x 100 x 7mm, whereas the various other knife types have length of 160-244mm, widths of 90-130mm, and thicknesses of c. 14mm. Most of the pieces weigh between 101-175gr, with individual ‘outsiders’ weighing up towards 1,600gr. The pieces from the Stourbrough Hill hoard form a distinct separate peak of light-weight knives, indicating the existence in the past of two production lines – one for delicate, well-executed pieces for ritual use and deposition, and one for general use with a potential for repeated re-sharpening. This suggestion is supported

further by the measurements of length, width and thickness, where the hoard’s specimens tend to form separate, tight peaks or clusters.

Almost all the faces are either flat or slightly convex, and it is thought that a small group of pieces with undulating faces may be expedient knives produced for everyday use. With the exception of two specimens, all Shetland knives are single-edged, with the two edges either polished sharp or blunt (rounded). The final sharpening polish was always carried out from one face. The ends are generally somewhat convex, although drop-shaped and crescentic pieces may have one or two pointed ends. Cutting-edges tend to be slightly convex, whereas blunted backs are usually straighter, or even slightly concave. Most of the knives have no corners at all, and the form of new pieces probably corresponded roughly to Piet Hein’s ‘super-ellipse’, that is, a hybrid form with elements borrowed from rectangles as well as ovals. A total of 32% of the specimens have discrete or more obvious corners.

Half of all Shetland knives show no signs of having been re-

worked, with two-thirds of these pieces deriving from the

Stourbrough Hill hoard. The other half of the knives show signs

of secondary modification, mostly in the form of re-sharpening,

although some backs have also been adjusted.

DISCUSSION

In connection with the examination of the felsite axeheads/

adzes and knives in Shetland Museum, 126 axeheads/adzes and

60 knives were characterized in detail, and all information was

subsequently stored in an Access database. The purpose of this

work was to allow discussion of formal variation within the two

artefact categories, focusing on raw material, typology and

technology. To determine whether axeheads/adzes and knives

in felsite may represent independent chronological or functional

groups, similar forms in other raw materials were also

examined. As shown below, the attributes selected for this

analysis did allow subdivision of the two categories, but to a

lesser degree than expected.

Axeheads/adzes

Raw material: The most notable formal subdivision of this category is that of felsite and serpentinite pieces. Although

some attributes produced a slight overlap of the two groups,

they generally form two relatively distinct categories, with the

felsite pieces mostly being ovate (pointed-butted), two-sided, and large and the serpentinite pieces thick-butted, four-sided,

and small. Both groups include axeheads and adzes, as well as

unused/little used and heavily used/recycled pieces. Although

during the analysis no distinction was made between ground and polished pieces (which in the case of felsite may form a

continuum), most felsite pieces clearly fall into the ground

category, displaying some striation of the broad-sides, whereas

the serpentinite pieces include several with polished, almost mirror-like broadsides.

Figure 24.

Piet Hein’s ‘super-

ellipse’ (courtesy of

Erik Vestergaard,

Haderslev

Grammar School;

Vestergaard 2005).

Table 18. Shetland knives with and without corners.

Corners Quantity Per cent

No obvious corners 27 45

No obvious corners/pointed 10 16

One to four discrete corners 7 12

One to four discrete corners/pointed

1 2

One to four obvious corners 11 18

Uncertain 4 7

TOTAL 60 100



On Shetland, only the axeheads/adzes from Modesty, West Mainland (Sheridan 2012) have been dated securely (although dates are expected from the analysis of felsite assemblages at Hill of Crooksetter and Firths Voe, just south of North Roe; Ballin 2011c; 2012b; Reay in prep.). The distinct differences in terms of general shape (ovate and thick-butted), sided-ness (two-sided and thick-butted) and size (large and small) raises the question of the chronological and functional relationships of the two groups.

In Britain, most work on axehead/adze variability has focused on raw material (eg, the different volumes produces by the Implement Petrology Group, such as the three Stone Axe Studies monographs; Clough & Cummins 1979; 1988; Davis & Edmonds 2011) rather than typological variation. However, in Denmark, where practically all stone axeheads/adzes are in flint, focus has been on the construction of chronologically and regionally diagnostic implement groups through typological variation (eg, Vang Petersen 1993). Analysis of the vast number of axeheads/adzes available in Denmark showed that pointed-butted, thin-butted and thick-butted axeheads were produced and used in different periods.

A number of implements in other raw materials (eg, basalt, gabbro, and schist) are thought to be individual expedient pieces.

Axeheads/adzes: Some attributes – such as, cross-section, profile along the long-axis, and edge-shape – allowed the implements to be subdivided into axeheads and adzes, that is, two functionally different groups of chopping tools. Both categories include felsite and serpentinite pieces, large and small pieces, as well as plain and exceptional pieces.

Functional vs ceremonial/prestige objects: Distinction between these categories was not immediately obvious. As also noted by Mahler (2010), the larger axeheads/adzes tend not to display any use-wear, indicating that they may have been produced for other than functional purposes, but

use-wear on its own was not enough to allow this question to be dealt with in an unequivocal manner.

However, the lengths and widths of the axeheads (Fig. 12) produced a clear distinction between two formal categories, namely smaller robust pieces with an average LW ratio of c. 2:1, and larger, slender pieces with an average LW ratio of between 3:1 and 4:1 (divide at 175mm). It is thought that the former category may be functional pieces, whereas the latter pieces may mainly have been manufactured to be used as ceremonial or prestige objects. Although other attributes did not produce two unequivocal groups, weight as an attribute suggested a likely distinction along these lines at 600gr; cutting-edge corners and edge curvature indicate that smaller and larger pieces may have been used to a higher and lesser degree (as also suggested by Mahler (2010, 18-19), with smaller pieces having more distinct corners and lower edge curvature ratios than larger ones, due to the effect of use on the edges.

Other categories: Four pieces have splayed edges, and two of these (ARC 65226, 65554) are so distinct and identical that they clearly represent a formal ‘type’. However, as they are both undated stray finds, and as they form a numerically/statistically very small group, it is uncertain what they represent. It has been suggested in the archaeological literature (eg, Mahler 2010, 23), that – due to superficial similarities to metal axeheads with splayed edges - they may be late, but at present (given the numerical size of the group) this is no more than a ‘guestimate’.

As, in formal terms, they are not just similar but identical (apart from minor size differences), it is possible that they simply represent the output of one workshop and from one exceptionally skilled knapper. Should this be the case, it is interesting to note that this workshop (whereever it might have been) serviced settlements as far apart as West Mainland and the southern tip of Shetland.

Shetland knives

Almost all knives are in felsite, and although some of the larger pieces are so notably larger than the majority of the group that they must have been used in a different way, or to process different materials, it is thought that most knives left the workshops as either sub-rectangular or oval pieces (Table 13), and that most differences in terms of outline represent varying degrees of use (Table 19). It was, however, possible to distinguish between pieces likely to have been produced for general use, and pieces produced as ceremonial/prestige objects and possibly intended for ritual deposition.

The 19 knives from the Stourbrough Hill hoard are all formally similar, although the highly patterned felsite on which they are based may have been procured from a relatively large number of different outcrops in North Roe. They are generally sub-rectangular/oval, relatively small (considerably thinner than most other knives), and unused.

Secondary modification Quantity Per cent

No apparent re-working 30 50

Outline indicates general re-working

4 6

Edge: Re-sharpened by polish (facet)

6 10

Edge: Re-sharpened by scale-flaking

16 27

Back: Re-blunted by pecking 1 2

Back: Re-blunted by polish (facets) 1 2

Back: Re-blunted by retouch 2 3

TOTAL 60 100

Table 19. Shetland knives with and without secondary

modification.



In comparison, other knives (which are most likely to be functional pieces) are based on relatively plain felsite, with varying shapes and sizes, and displaying signs of having been used and rejuvenated.

Comparison between the axeheads/adzes and the Shetland knives

As shown above, it is possible to define similarities as well as differences between the felsite axeheads/adzes and knives, some of which may inform on the prehistoric systemic context (Schiffer 1972), whereas others may be artificial constructs relating to the fact that the objects from Shetland Museum represent a relatively small statistical population, which is not entirely representative without the addition of the collections from the three large Central Belt museums.

As mentioned in the raw material section, there appears to be a notable difference between the way felsite was selected for axeheads/adzes and knives, with the former tending to be plain and the latter more spectacularly patterned. It is quite likely that this difference may be real, as the robust way a chopping implement is used, as compared to a cutting implement, may make patterning undesirable in the former case – if an exehead/adze had banding or large spherulites, it would be quite likely to break along these bands, or along the edges of any spherulites present, during use.

However, considering the fact that some axeheads/adzes are characterized by discrete banding or the presence of small spherulites, in conjunction with the fact that close to half of all intact knives form part of the unique Stourbrough Hill hoard, it is possible that the perceived raw material differences between axeheads/adzes and knives has been exaggerated. This needs to be tested by examination of the collections of felsite artefacts in National Museums Scotland, the Hunterian Museum and Kelvingrove Museum.

The analysis showed ‘beyond reasonable doubt’ that both categories include pieces for everyday use (‘functional tools’) as well as ceremonial/prestige objects (Figs 12, 21). Axeheads/adzes seem to have been perceived as particularly impressive/desirable if they were large and elegant (slender), whereas the latter were perceived as impressive/desirable if they were small and delicate (thin). Although the raw material differences between the two categories may have been exaggerated (above), there is little doubt that the large axeheads/adzes are considerably less spectacularly patterned than the small ceremonial knives (eg, the Stourborough Hill hoard). The axeheads/adzes, as well as the knives, produced as ceremonial/prestige objects have one thing in common, namely their exquisite execution.

Emic/etic types and the chronology of axeheads/adzes and Shetland knives

The definitions of emic and etic types were proposed by anthropologist Kenneth Pike (1954) and further elaborated on by, inter alia, Harris (1968) and Hayden (1984). Emic

refers to the way for example archaeological groups classified their objects or behaviour, whereas etic refers to the way for example archaeologists classify objects or behaviour to resolve specific research questions. Etic types do not necessarily have any relevance to the way archaeological groups perceived their world or classified its objects (including their own tools).

As shown above, it is possible to subdivide both implement categories into a large number of formal sub-types (eg, sub-rectangular, oval, drop-shaped, etc. knives), but it was also argued that most of these sub-categories may largely be products of repeated use and rejuvenation – that is, most groupings represent etic classification. That does not mean that these types are not relevant to our interpretation of the prehistoric systemic context, but their different shapes, sizes, etc. do not represent mental templates (emic types) deliberately produced by the prehistoric knappers. In terms of the felsite axeheads/adzes, only the distinct axeheads with splayed edges seem to represent an emic addition to the dominating ovate pieces.

This may have a bearing on the chronology of the felsite axeheads/adzes and knives, in the sense that production of these implements over a considerable time-span would have been likely to result in the formation of a sequence of

diagnostic types (like the Danish pointed-butted thin-

butted thick-butted sequence; eg, Vang Petersen 1993). As the axeheads/adzes are almost exclusively ovate forms and the knives sub-rectangular/oval forms, these felsite implements may have been manufactured over a relatively short span of time. However, this needs to be tested by the examination and recording of the pieces in the exhibitions and stores of the three main Central Belt museums, as well as by the examination of new pieces from well-dated, excavated (settlement, burial, or other) contexts.

A group of felsite knives from Shetland Museum

(Photo courtesy of Kirstine Møller, University of Copen-

hagen )



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Editor NRFP Report Series: Gabriel Cooney and Joanne Gaffrey

Published by School of Archaeology,

University College Dublin,

Belfield, Dublin 4, Ireland

Except where otherwise noted, this work is licensed under a Creative

Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

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Cover Image: Group of knives from Shetland Museum (Photo: Kirstine Møller, University of Copenhagen ) Background Image: Felsite knives and axes/adzes from Shetland Museum (Courtesy of Jenny Murray, Shetland Museum) Recommended citation: Ballin, T., 2015. Making an Island World: Neolithic Shetland. Felsite polished axeheads/adzes and Shetland knives in Shetland Muse-

um—recording, characterisation and interpretation of the collection . North Roe Felsite Project Report 2, UCD School of Ar-

chaeology.

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