0353 - Segments

For some time now I have been stressing the fact that some Portuguese ditched enclosures present evidences that the ditches are built by segments and/or are filled by segments. In this year campaign at Perdigões another situation was recorded, but for the first time to the early period of enclosure building in South Portugal (around 3500 BC).

Here is a section of Ditch 13 where a clear segmented filling can be appreciated. 

That tell us several things:

a) we cannot generalize to a ditch perimeter the observation done in one small section;

b) ditches have a complex biography of excavation, fillings, re-excavation and re-fillings;

c) those processes are mainly anthropic, intentional and meaningful;

d) as any other complex context, the excavation of ditches requires adequate inquiries, theoretical tools and methodological approaches.

0320 - Issues from Porto Torrão

In 2002 two sections in two ditches of Porto Torrão were excavated by Era Arqueologia (Valera, Filipe, 2004; Valera, 2013). In that area the ditches are just 8 meters apart. For the inner one (ditch 1), material culture and radiocarbon dating say that it was open and filled almost to the top during Late Neolithic (end of the 4^th millennium BC/transition to the 3rd). The last filling deposits, though, are from Late Chalcolithic. The outside one (ditch 2) was open by the middle of the 3^rd millennium BC and the filling went on until the end of the millennium (according to radiocarbon dating). That means that when the outside ditch (ditch 2) was opened the inner one (ditch 1) was visible and not completely filled, what just happened in simultaneity with the later filling of ditch 2. So, why opening a new ditch just 8 meters apart, having to excavate bedrock, when a previous ditch was just there, visible and easier to re-excavate? Well prehistoric communities do not respond to modern principles of effort-profit and this particular situation (together with many others in other ditched enclosures) should make people, at least, wondering.

References:

Valera, António Carlos e Filipe, Iola (2004), "O povoado do Porto Torrão (Ferreira do Alentejo): novos dados e novas problemáticas no contexto da calcolitização do Sudoeste peninsular", Era Arqueologia, 6, Lisboa, ERA Arqueologia/Colibri, p.28-61.

Valera, A.C. (2013), “Cronologia absoluta dos fossos 1 e 2 do Porto Torrão e o problema da datação de estruturas negativas tipo fossos”, Apontamentos de Arqueologia e Património, 9, Lisboa, Nia-Era, p.7-11.

0315 - Perdigões ditch 7 is dated.

 

Perdigões ditch 7, another one with structured depositions and human remains, is now also dated by three radiocarbon dates that put its filling and re-cuttings between 2600 and 2200 BC. This ditch has one of the most interesting sequences of filling of Perdigões ditches, for it has a sequence of depositions that seem to have been deliberately closed by a stone “cairn”. After that the process of filling changed. That sequence is well dated by these three dates. But some more are needed.

0309 – Back to Perdigões

Next week I will be back to Perdigões to finish the section in ditch 7. In this section the ditch is already 3 meters deep and, although it is quite narrow down there, the walls are still quite vertical. So it is not easy to estimate how much deeper it will go.

Note that the section is in the area where ditch 7 is starting to overlap ditch 8 (a previous Neolithic one). So the inner wall of the ditch (right in the image) is, in this area, constituted by the sediments that were filling the previous ditch. This filling, that goes until about 2 meters deep (ditch 8 was less deep), is constituted by deposits of earth with faunal remains and pottery shards. But this wall of earth was not eroded and it would have been easily if exposed to winter rains. This means that ditch 7, at least in this section, had to have been opened and rapidly filled.

And as you can see in the section, after it was filled (with a sequence of layers of stones, faunal – and human – remains and pottery shards) it was reopened through a recutting, then filled with layers of stones.

This is a stratigraphic sequence of openings and deliberate fillings that shows the nature of this ditch. A ditch that defines a inner enclosure that I now think that can be related to a later, complex and highly symbolic occupation of the central area of the natural theatre where Perdigões stands.

0269 – Processes of ditch filling

A paper about the processes of filling of the Late Neolithic ditches of Perdigões enclosures will be presented by the end of the month at the VIII Iberian Southwest Archaeology meeting.

Late Neolithic ditches (yellow) in the central area of Perdigões.

The goal is to confront theoretical interpretations in dispute regarding the nature of these type of contexts with empirical data, arguing that the processes of filling and what we find inside ditches are important criteria to the interpretation of functionalities. It seems obvious, and yet still needs to be stressed. 

Bottom depositon in Ditch 12.

0146 – Ditches 8 and 12 of Perdigões

Ditch 8

Ditch 8 is still in excavation (it will be finished this summer). It is interesting to notice that the already excavated part has a sequence of deposits that concentrate large amounts of pottery shards and faunal remains (once again almost just pottery a fauna), in a horizontal surface at the centre of the ditch. There were at least three of those layers, separated by deposits with less and more disperse material.

This is a situation that reminds the cover of pottery shards that ended the filling of ditch 12 (the one with the “Almeriense Idols” deposited at the bottom (see here).

 Ditch 12 and 6. Red dot in ditch 12 are pottery shards.

These kinds of depositions inside ditches keep repeating at Perdigões enclosure. 

0127 - Bit by bit

This is the way the outside ditch of Bela Vista 5 was done. Not at once, but by a sequence of short ditches, that were overlapped and are different in depth and thickness, as we can see from the different profiles obtained in several areas (an image from the archaeological report in preparation) and from the distribution of stone concentration in the surface of the sequence.

In some of them we can see evidences of re-cutting.

 

Naturally this delimitation has no functionality for defence or water circulation or other more practical goal. The sections were made to be filled (and some were filled before the next section was opened). And they are filled with stones and pottery shards: no faunal or human remains, no stone tools, no loom waits were recovered in the surveyed areas of this “ditch”. Just pottery, showing a clear selection of a particular category of material.

Faunal remains appear in some of the inside pits. The inside small ditch, on the contrary has some faunal remains associated to the pottery shards, and enclosures an area with just a pit grave. All the data from this enclosure points to a place of highly ritualized practices.

After the report is complete we intend to publish a monographic paper on this important site.

0111 - Re-excavating ditches

Sections of the outside ditch at Bela Vista 5:a previous layer was excavated in the centre and after refilled with other deposits.

This is, in a certain way, another version of overlapped ditches problem. In fact, it is frequent to record evidences of ditches that were reopened, by the re-excavation of part of its previous fillings. It is important to notice that only when the reopening is partial is it

detectable by archaeology. The total remove of previous filling deposits leaves no evidence, and if they occurred, then these activities would have been even more common.

This creates problems to ditch dating, because there might be a significant time between the initial excavation of a ditch and its last filling sequence. Only with several sections and good dating sequences we can evaluate these problems.

But another problem is why they reopened some ditches? And why frequently just a central part of the ditch, leaving a ditch with “walls of sediment”? Is it because they want to rapidly fill it again with new deposits and materials? They must have done so, otherwise those “walls of sediment” would have been eroded (and we can clearly see them in some sections, like the one presented here).

This kind of stratigraphic sequences points to human intentionality in the formation of the deposits inside ditches, not just because of the materials or the structured organization they might present. The structure of the deposits itself may be an argument to that intentionality.

0106 - “Idols” in ditches

Is the second situation in Perdigões, separated from the first one by more the 500 hundred years: the depositions of idols in the bottom of ditches.

The first situation was detected in ditch 1 (Mata et al., 2011), dated from de second half of the 3rd millennium BC. A schist idol, with lateral cuts, was found deposited just at the bottom of the ditch, associated to a complete pot and some faunal remains.

 

 

Idol in Ditch 1 (After Mata et al. 2011)

 

The second situation was recorded this year, in ditch 12, dated from Late Neolithic. An assemblage of 5 Almeriense Idols was recovered at the bottom of the ditch. I am just finishing a paper on this context that will be published next October.

 

Idols in ditch 12.

These situations, although apart in time, document a same general fact: the filling of the ditches was, frequently, the result of intentional human action and they might document a ritualization of the beginning of those processes. Unless we admit they were just lost by someone passing by.

More and more evidences are appearing every year to create problems to the “erosion” and “garbage” explanations of ditch fillings and to support other interpretations that take into account human activity and intentionality.  

References:

Mata, E., Fernández, J. e Caro, J.L. (2011), "Figurinha en xisto procedente del relleno del foso 1 del complexo arqueológico dos Perdigões (Reguengos de Monsaraz", Apontamentos de Arqueologia e Património, 7, NIA-ERA, p.19-21.

0098 - Dating ditch fillings

Dates from ditches 3 and 4 from Perdigões. They are Chalcolithic ditches, dated from the 2^nd quarter and middle 3th millennium BC. But in a top layer of ditch 4 we got a Late Neolithic date (a ditch that has to middle 3^rd millennium dates for bottom deposits). A typical situation of incorporation of earlier material. In fact, just 3 meters away there was a Late Neolithic pit burial that was disturbed in Chalcolithic times. Taken from Valera & Silva, 2011.

Dating the fillings of ditches and interpret the results is a tricky issue.

First, we must be aware that we never date the opening of a ditch, only the beginning of its filling. And we do not know the time between the opening and the beginning of the last filling process of the ditch (I say last because we must considerer the possibilities of re-openings).

Second, what is integrated in the ditch filling may be older than the filling process or even older than the excavation of the ditch. In fact, especially in sites with long living periods (like Perdigões, for instance), where earlier materials can be about or the excavation activity is so intense that earlier deposits are constantly being remobilized, it is natural that some of the material that integrates a filling deposit inside a ditch is actually from earlier occupations. By dating this material we will not date what we intent to. We will be dating earlier material that has nothing to do with the time the ditch building or its filling moments. That is why sometimes we have earlier dates in top deposits and later ones in the bottom deposits.

So, how can we avoid these problems?

Dating ditch fillings implies dating series of samples, where outliers can be detected. It is not just the need of dating the sequence of deposits to determine the filling rhythm (which is, of course, important). Even if there are just one or two deposits, we must have more than just one date, precisely because of the problems raised by the typical dynamics and activities that take place in this kind of sites.

It is more expensive, I know. But one date in a ditch, except if you have a well defined and closed context (like a burial, for instance), is far from enough. And every date or series of dates need a serious critique, regarding the dating procedures, dated material, relation to context, nature of the context formation, post depositional events, and so on. Or we will just adding smoke to an already foggy area.

Bibliographic References:

Valera, A. C. & Silva, A. M. (2011), “Datações de radiocarbono para os Perdigões (1): contextos com restos humanos nos Sectores I e Q”, Apontamentos de Arqueologia e Património, 7, Lisboa, NIA-ERA, p.7-14.

0094 – The irregularity of ditches.

The inner ditch of the enclosure in excavation process: 1,5m deep in first plan survey (back of the dich); 1,3m deep in the next one; 0,8 at the gate. Notice the presence of a layer of geological material at middle depth.

The irregularity of ditches, not in plan, but in depth, is another issue that is very important to question functionality and meaning.

It is expectable that a ditch to accomplish the function of defence or infrastructure of a palisade presents a general regularity in terms of depth. The problem is that for almost all Portuguese ditched enclosures only small parts of ditches were surveyed. But recently to exceptions to this “rule” allow treating this problem.

At Senhora da Alegria, a small enclosure (about 10 meters diameter) at the top of the site presented a circular plan with one gate and only a pit inside. The pit had inside large fragments of burned wood and the ditch revealed a interesting depth profile: it grows deeper from the back towards the gate, with a significant slide percentage.

At the enclosure in process of excavation in Alentejo the inside ditch presents a similar size and also just one gate. But the depth of the ditch reveals the opposite behaviour: it grows deeper from the gate sides to the back: 0.8 / 0.4 at both sides of the gate and 1,5 at the back of the circle. So it presents also a significant slide. Inside, also just one pit, still in excavation (sealed with stones and with complete pots underneath).

What the strange behaviour of the depth of these ditches suggests is that they cannot be associated to any kind of palisade or regular barrier: were they built to be walked inside, from the surface to a deeper area? It has something to do with water circulation and accumulation in a specific area of the ditch? I recall that at least one of the ditches of the enclosure of Águas Frias the structure also ended in a sort of ramp. Let us see what this new enclosure has to reveal in the next days. For the moment the fillings of the ditches are as heterogeneous as their depths.

The back of the ditch: note the absence of geological material layer just one meter away from the other profile.

0075 – Processes of ditch filling

Dog skull inside ditch 3 of Perdigões.

The nature and the processes of ditch fillings are central to ditched enclosures interpretation. Several elements can be analysed to try to understand those processes. One of them is fauna.

Usually, faunal remains are approached in terms of levels of articulated bones, present and missing bones, structure of the deposition of the bones, animals represented and other associated elements.

Recently, a study of faunal remains from ditches 3 and 4 of Perdigões enclosure done by Cláudia Costa (“Problem of filling the ditches 3 and 4 (Sector I) of Perdigões (Reguengos de Monsaraz”, Estudos do Quaternário, 6, APEQ, Porto, 2099/2010) based on stratigraphic analysis of faunal remains”) showed that the taphonomical approach is also quite relevant and that, together with the analysis of other present elements, can be a precious help to interpret the formation process of the fillings.

Here is what she says in the papers abstract:

“During archaeological intervention on sector I of Perdigões ditch enclosure (Southern Portugal), dated from the IIIrd mil¬lennium B C, a section of Ditch 3 and 4 were excavated. The ditches are parallel “V” shaped structures, excavated on local bed rock, of 1,70 m (Ditch 3) to 2 m (Ditch 4) deep.

The ditches were filled with a sequence of anthropic sediments with archaeological artefacts, mostly potsherds, and vertebrate fauna. The species present in both ditches are suids, the most numerous, followed by bovids (domestic, and an element of an auroch), ovi¬caprids, red deer, horse, dog/wolf, rabbit and hare. The anatomical representation is the opposite in each ditch: in Ditch 3 the most common elements are from cranial and appendicular skeleton, whereas Ditch 4 is filled mostly with elements from axial skeleton. This aspect linked with the specific spatial association of bones and other elements, as pottery or pebbles, with an unequivocal intentional organization, doesn’t seems to fit on the pattern of secondary refuse. The faunal remains seem to integrate the “intentional depositions” at least on some points of the sequence.

On both structures, faunal assemblages are more fragmented on top of the sequence, and on the base, faunal remains tend to be more complete. The transition of more fragmented to less fragmented bones is materialized by intentional depositions layers, unit 58 on Ditch 3 and unit 34 on Ditch 4. On the other hand, in some stratigraphic units, root etching was identified on bone surfaces. Root etching is linked to vegetation that settles on soil profiles top, on the early stages of pedogenic developments. The existence of this phenomena point to a discontinuous filling process of the two ditches, where stratigraphic units remain stable and exposed long enough to pedo¬genetic process begin. On Ditch 3, the assemblage from unit 58, interpreted as “structured depositions”, is one of the most affected assemblages by root etching, which means that after sedimentary formation and installation of “depositional structures”, the unit was exposed. The same unit was affected as well by a natural water channel that mutilates the unit’s surface.
The other natural taphonomical signatures are manganese oxide, which affects continuously all remains from Ditch 3, and in a low percentage Ditch 4, and carbonate calcium that particularly affects the base assemblages in both ditches. This aspect reveals the strati¬graphic stability of the sequence.”

0064 – A (fragmented) sequence of ditch 4 of Perdigões

Horizontal and localized depositions of stones, pottery shards and faunal remains, separated by clay deposits. At the bottom, some stone agglomeration, before a layer with calcite precipitation.

0042 – Where have all the flowers gone?

Carrascal (Porto Torrão) ditch excavated by ERA Arqueologia (responsibility of Helena Santos)

I frequently remember the name of this song when I think about all of the geological material that was extracted in the processes of building ditches. Where have all the tons of geological material gone?

As I’ve said before, we completed this year a cross section in Ditch 6 of Perdigões, dated from Late Neolithic. This, combined with the plan obtain by geophysics, allows us to estimate the volume of bedrock extracted. Assuming similar shape and measures (sometimes they change along the ditches) of Ditch 6, that has almost a two hundred meters perimeter, the building process implied the excavation and removing of about 745 m3 of geological material (I will also calculate the weight).

I will deal later with the questions of logistics, labour and technical problems. For now I just renew the question: where is it?

Traditionally is assumed, I repeat assumed, that bank walls were built with that material, later eroded. The problem is that there are no evidences of that erosion in any of the already surveyed ditches at Perdigões (as in other Portuguese enclosures). They simply are filled with different materials (with exceptions for small erosion of ditch walls, as we can observe in a specific point of Ditch 6).

But the geological is also not outside the ditches, not even in Perdigões, that is topographically an amphitheatre, with the pendent orientated to the inside and East. Ditch 6 is in the centre of the natural amphitheatre. If there was a bank by the inside of the ditch built with the geological material there should be evidences of it. There are not.

If we think that at Perdigões are at least 11 ditches, progressively bigger than Ditch 6, we start to have an idea of the quantity of geological material removed there over time. Thousands of cubic meters; thousands of tons (it is now possible to also estimate the volumes for ditches 1, 3 and 4).

Where is it?

0041 – Late Neolithic ditch at Perdigões enclosure

In this year campaign we reach the base of Ditch 6 (the inner one) of the complex of ditched enclosures of Perdigões. It is 3 meters wide at the top, 2 meters deep and has a “u” section.
From bottom to top provide mainly faunal remains and pottery, addressed to Late Neolithic (second half of the 3rd millennium BC).
















The processes of ditch filling of this section is different from the ones observed in Sector I, in Ditches 3 and 4, dated from plane Chalcolithic. As in Ditch 3 a significant change has been observe in the first half of the ditch, regarding the second (upper) half, separated by a moment of local erosion of the western wall of the ditch (not extendable to the entire surveyed area). In the lower part we have basically horizontal layers, with a moment of organized depositions of stones. After the wall erosion period, we have diagonal sedimentation pending from west (from the outside of the enclosure), including moments of formation of stone layers with the same pending.




















The interpretation of this filling is still yet to be done (excavation just finished). But it is clear that the process had different phases (with different conditions) and doesn´t present clear structured depositions as can be observed in Ditches 3 and 4 (Mind that we are talking about small section of long ditches). Nevertheless, is a big ditch by Late Neolithic standards, only overcame in Portugal by one of the ditches excavated at Porto Torrão (Valera & Filipe, 2004).

0027 - Drying the enclosures

Lots of things can happen inside a ditch, like discussions between archaeologists, for instance.

The data coming out of ditches, when conveniently published, ravels that many actions took place inside, some of natural origin, most of human initiative. Along the filling layers we can detect organized depositions, pits dug in previous layers, stone structures, human burials, etc. In Portuguese enclosures, we can observe this in several sites where excavations are larger than a small section: Perdigões, Santa Vitória, Porto Torrão are some examples.

Structured deposition inside ditch 3 of Perdigões.

This is not very consistence with the idea that those ditches were built to be water canals or drains, a justification that continues to be too easily adopted in some discourses. And another inconsistence is the topography (which I already classified as very important in enclosures interpretation). Most of those enclosures are in slopes, with significant differences of altitude between the several sections of the ditches. Because of the water levelling, this topographical situation implied that water would concentrate in lower sections, living large parts of the ditches dry when the water was less, overflowing the ditches when the water was too much.

But of course water run inside ditches in rainy days. That is inherent. And when it rained hard, erosion took place, just like ditch 3 of Perdigões shows at middle depth. This could be an argument for the drainage theory. But in sites with the topography of Perdigões, an amphitheatre, the water would run rapidly to East and concentrate in the upper side of the entrances that interrupt the ditch, generating a pull and overflow the entrance. At Xancra and Monte do Olival, located in slops orientated to East and with their entrances also in the eastern parts of the enclosure, this would mean a permanent flooding of the doors and of the low parts of the enclosures. This would be very inconvenient and, mostly, would have left evidences in the strata sequence that was not yet recorded in the excavated sites.

A drain should not be interrupted and should be proportional to the draining needs. So why built drains of 7 meters wide and 3,5 meters deep? That’s a canal of the Industrial Revolution. Why built wavy drains of 2,5 meters wide and 1,5 deep to drain an area of 20m diameter at Santa Vitória or Outeiro Alto 2?

For all those reasons, water canals and reservoirs or draining structures are not very consistent primary functions to explain the building of the most part of ditched enclosures. Water flows inside them. But as intrinsic circumstance that comes along with this kind of structures. Not as an intended one for the building decision. And if there are exceptions, they must be empirically demonstrated by evidence from strata sequences inside ditches and by topography consistence and not simply assumed.

Reconstruction of the set of enclosures of Los Marroquiés Bajos (Jaén, Spain), assuming the ditches as water canals

0025 - Dogs, depositions and ditched enclosures

Dog skulls in Ditch 3 of Perdigões

Dog skulls in ditch 3 of Perdigões. This situation drives us to the classic problem of “is it ritual or rubbish? (Question asked by Hill, 1996). The question is, in fact, a version of the much larger problem of identifying and interpreting human intention in Archaeology (especially Prehistoric). The debate developed a concept, structured depositions, which have been used to fulfill the semantic emptiness that emerged with the criticism to the use of the modern notion of rubbish (a meaningless discard with no value and no importance).

The criticism lays in the perception that what is unsacred today and understood as waste and without value, could, in different social contexts, correspond to meaningful and symbolic actions. Therefore, we would be in presence of “structured depositions” and not chaotic and unorganized rubbish.

So, “structured depositions” emerge as a designation that “saves us” from precipitated projection of social practices anchored in modern systems of references, allowing the emergence of different intentions and different contextual social meanings.

Nevertheless, as Olsen (2000) puts it, the designation in itself doesn’t offer any explanations or interpretations regarding the nature of the depositions. Therefore, context and pattern play a decisive role in defining that nature and ultimately in distinguish rubbish from other intentional depositions.

And the context of this ditch in Perdigões is one of horizontal deposition of layers of stones, pottery shards, and faunal remains (but no other dog bones except from the skull parts). They are selected materials that are not representative of the totality of materials that circulate at the site at the time nor of dog skeleton. On the other hand, depositions of dog skulls (or heads) seem to define a practice all over Europe in the period. In Iberia, the case of Camino de las Yeseras (Liesau et al. 2008) is a reference: a ditch enclosure where in a pit several dog heads were deposited in a organized way after being cut off. In a lot of other places, the presence of dog remains corresponds only to parts of the skull (inclusively in Perdigões ditches 3 and 4): San Juan Ante Portam Latinam, Mas d’en Bixos, Pou Nou 2 and 3, Marroquiés Bajos, Picarcho, Quinta do Anjo or Alcalar 7.

And when is not the skull, are the paws in anatomical connection. In fact, the problem of structured depositions is quite linked to another one, and both should be address in the context of the same mental framework: the problem of body segmentation, shared by animal and human treatment of remains. Segmentation and valorisation of parts seems to have played an important role in the social fabrics of those societies. In fact, we are talking about segmentary societies. Segmentation is strategic and structural (Valera, 2010b). And ditch enclosures are a major context to address this problem.

(in Valera, 2010a, adapted)

References:

HILL, James D. (1996), “The identification of ritual deposits of animals: a general perspective froam a specific study of ‘special animal deposits’ from the Southern English Iron Age”, (S.Anderson e K. Boyle, Eds.) Ritual treatment of human and animal remains, Oxford, Oxbow Books, p.17-32.
HILL, James D. (2000), "Can we recognise a different european past? A constrastive archaeology of Later Prehistoric Settlements in Southern England", Interprettive Archaeology. A reader., (J. Thomas ed.), London, Leicester University Press, p.431-444.
LIESAU, C., BLASCO, C., RIOS, P., VEGA, J., MENDUIÑA, R., FRANCISCO BLASCO, J., BAENA, J., HERRERA, T., PETRI, A. e GÓMEZ, J. L. (2008), "Un espacio compartido por vivos y muertos: el poblado calcolítico de fosos de Camino de las Yeseras (San Fernando de Henares, Madrid)", Complutum, 19(1), Madrid, p:97-120.
OLSEN, Sandra L. (2000), "The secular and sacred roles of dogs at Botai, North Kazakhstan", (Crockford, S. ed.), Dogs through time: an archaeological perspective, Bar International Series, Oxford, p.71-92.
VALERA, A.C., NUNES, T. & Costa, C. (2010a), “Enterramentos de canídeos no Neolítico: a Fossa 5 de Corça 1 (Brinches, Serpa)”, Apontamentos de Arqueologia e Património, 5, Lisboa, Nia-Era, p.7-17.
VALERA, António Carlos (2010b), "Marfim no recinto calcolítico dos Perdigões (1): "Lúnukas, fragmentação e ontologia dos artefactos", Apontamentos de Arqueologia e Património, 5, Lisboa, NIA-ERA Arqueologia, p. 31-42.

0018 - Filling ditches

Ditch 3 at Perdigões set of enclosures

One of the main questions on ditched enclosures is the nature of the filling processes of the ditches. Natural courses, usually surface erosion; human activity associated to discarded rubbish; human activity related to structured and meaningful depositions. These are the most debated origins to explain the deposits inside ditches. But, once again, theoretical debate and empirical evidence kept missing each other, resulting in axiomatic disputes.

In Perdigões enclosure, ideas are being tested. Different ones. Competing ones. Ideas that may be conciliated. Ideas that cannot.

Regarding the filling processes, the wavy ditch 3 revealed an interesting situation (Valera, 2008). A first dynamic of clear human origin, characterized by horizontal depositions of layers of stones, pottery shards and faunal remains (also with some human remains) was in course until the middle filling of the ditch. This process was dated by radiocarbon from the first half of the 3rd millennium, with equal dates from the bottom and the top of this first sequence, suggesting a relatively "rapid" filling (Valera & Silva, 2011).

Then, an episode of hydro erosion occurs inside the ditch, excavating a canal and generating sedimentation of silt layers, with little archaeological material.

Section of Ditch 3 and calibrated radiocarbon dates (two sigma)

The filling of the upper half of the ditch corresponded to a different dynamic. Structured depositions of human origin continued, but were much more restricted and of different nature. The archaeological material is now of smaller size and more disperse. Stones are rare. And the radiocarbon date for the beginning of this phase points to the middle of the millennia, statistically representing a latter moment.

The sequence was also independently detectable in the faunal analysis (Costa, in print), confirming the stratigraphic observations and radiocarbon dates.

So, we can conclude:

a)The ditch had a initial phase of filling where human horizontal and structure depositions took place, choosing particular elements: stones, pottery shards and faunal remains (with some human bones also);

b)This process, apparently rapid, stopped at middle ditch depth, and a hydro erosion process dug a small canal on the surface of the filling deposits.

c)After some time (which means the ditch half full was open for some time) a new process of filling begun, with different characteristics, where human and natural processes seem to conjugate.

d)No evidence of bank erosion was detected inside the ditch, and another one (Ditch 4) was excavated just 2,5 m distance by the inside. Radiocarbon dating shows that this opening was contemporary of the 2nd phase of the filling of Ditch 3, that definitively didn´t have an associated bank.

This process reveals that there is a decisive human intervention on the filling that, at list in the first phase, is much more important than natural processes. It also shows that the association of ditches with banks must be demonstrate and not simply presumed. Finally, it demands theoretical explanation of the nature of the human depositions, also empirically tested in honest ways and not axiomatically (or devotedly) assumed.

Why was this ditch opened and filled partially with selected materials that don´t represent a natural assemblage of the artefact universe of the communities? Why that process stopped at a certain stage and another ditch was open just a couple meters way? Why the ditch was softly waved? Why there are no evidence (on the contrary) of palisades or banks associated to it? Why are there human remains inside the ditch? Why is the ditch section profoundly asymmetric? Why...

In fact, before answer, and instead of assume, we must ask.

References:
Costa, Cláudia (in print), "Problemática do enchimento dos Fossos 3 e 4 (Sector I) dos Perdigões (Reguengos de Monsaraz) com base na análise estratigráfica dos restos faunísticos", III Jornadas do Quaternário. Evolução Paleoambiental e Povoamento no Quaternário do Ocidente Peninsular, Universidade do Minho, Braga.

Valera, António Carlos (2008), “O recinto calcolítico dos Perdigões: fossos e fossas do Sector I.”, Apontamentos de Arqueologia e Património, 3, Lisboa, NIA-ERA, p.19-27.

Valera, A. C. & Silva, A. M. (2011), “Datações de radiocarbono para os Perdigões (1): contextos com restos humanos nos Sectores I e Q”, Apontamentos de Arqueologia e Património, 7, Lisboa, NIA-ERA, p.7-14.