491

Remote Sensing and Ground-Truthing of a Medieval Mound

(Tuscany - Italy)

S. Campana,1 R. Francovich,

2L. Marasco

3

1 University of Siena, Department of Archaeology and History of Arts, Landscape Archaeology, (LAP&T)

campana@unisi.it2 University of Siena, Department of Archaeology and History of Arts, Medieval Archaeology

francovich@unisi.it3 University of Siena, Department of Archaeology and History of Arts, PhD Student, (LAP&T)

marasco@unisi.it

1 Introduction

The site which we propose to discuss in this paper was

‘discovered’ from the air in the summer of 2005 during

the University of Siena’s XIVth International Summer

School in Archaeology. It lies close to the castle of

Scarlino, facing the sea on the west coast in the province

of Grosseto.

The landscape of this area has been studied by the

University of Siena’s Department of Archaeology since

1979, when Riccardo Francovich started archaeological

excavations at the castle of Scarlino (Francovich 1985).

Shortly after the start of the excavations, work also began

on a programme of field-walking survey that has helped

to make this one of the best-studied landscapes in the

province of Grosseto (Cucini 1985).

The site had already been identified at an earlier stage

through the air photo interpretation of vertical historical

coverage (Cosci 2005). Unfortunately the absence of a

detailed map of the features and the unavailability at the

time of these earlier studies of GPS navigation made the

identification of the evidence in the field extremely

difficult. Field-walking survey and ground-truthing

variously suggested a positioning either one side or other

of the apparent air photo location, without ever revealing

its true position or scale (Chapman 2001; Campana

2005). Although analysis of the aerial photographs

allowed the site to be interpreted as a triple enclosure, the

lack of its correspondence on the ground with any

artefactual evidence prevented us from obtaining any

understanding of its chronology or of its potential

contribution to the development of new settlement

patterns in the area. In this context we should perhaps

Figure 1 Overview of the landscape

FROM SPACE TO PLACE

492

note the difference in familiarity with this kind of site in

Italy as compared with other parts of Continental Europe

or the United Kingdom. In Germany or England, for

instance, archaeologists would find it quite easy to

interpret this kind of feature without the need for ground-

truthing, but in Tuscany this kind of evidence has no

immediate parallels or comparisons.

In this paper we will show how the quality and the

quantity of the information was supplements by more

recent studies. Using this new evidence we will then

discuss the new perspective which this opens up for

archaeological research in the surrounding landscape.

2 The local landscape and historical

background

The site, whose placename Castellina indicates its

possible relationship with a castle, is set at the centre of a

large area of lowland fronting onto the Gulf of Follonica.

The area may have been characterised in the past by a

wide brackish lake. Attempts at reconstruction of the

ancient lake boundary would set our site close to the

ancient coastline (Bartolini et al 1977).

The shoreline extended approximately from our site to

the base of the hill on which stands the castle of Scarlino.

The navigability of this salty lake is still documented in

the late Middle Ages but was impeded in the following

centuries by a progressive dessication of the area,

creating an un-navigable swamp. The archaeological

study of the site is still in its early stages but there

appears at first glance to be a clear relationship with the

surrounding landscape context and with the development

of economic activity in the area. Past researches have

concentrated on interpretation of the medieval landscape

as being focused, from the early Middle Ages, around the

hilltop village of Scarlino. Here the archaeological

excavations, above settlement evidence from the Bronze

Age to the days of imperial Rome, revealed firstly the

remains of an open village, later converted into a curtis in

the ninth century AD and finally transformed into a castle

settlement from the end of the tenth century onwards

(Francovich 1985).

More recently a new study of the archaeological data

from the Scarlino excavation has furnished interesting

comparisons for the pottery recovered from the site

(Marasco forthcoming). Furthermore, the archaeological

evidence has been supplemented by a rich archive of

early medieval documentary sources relating to the

Bishopric of Lucca. The integration of the various

information sources has allowed us to recognise that,

after the crisis of the Late Roman period, the rural

landscape of this area was characterised between the

seventh and eighth centuries by the presence of villages.

The development of the settlement pattern at the

beginning of the early Middle Ages followed two main

paths: the concentration of population centres and the

beginnings of hilltop villages.

Figure 2 Oblique air photograph of the cropmark features and their relationship to the central place of

Scarlino

The archaeological excavations at the castle of Scarlino –

and at many other excavations – allow us to describe

some aspects of these villages during the seven to eighth

and ninth centuries AD. They consist mainly of wooden

huts, organised into a central nucleus and sometimes

defended by palisades or other forms of enclosure.

During the eighth century the documentary sources attest

to the growth of a new form of resource-management and

exploitation, the curtis system. The archaeological

investigations show the overlap between these new

system and the preceding settlement pattern. In the same

century the archaeological sources show the

transformation of the villages and it is now possible to

recognize evidence of spatial organisation related to the

exercise of management and power.

However, many hilltop villages did not succeed in taking

on the role of centres of human aggregation, perhaps

because of the weakness of the local aristocracy or

because of competition with other developing centres.

The site that we discuss in this paper is one of these latter

cases – a failure site. The site evidence represents an

early Middle Age survival – not necessarily a direct one –

S. CAMPANA, R. FRANCOVICH, L. MARASCO: REMOTE SENSING AND GROUND-TRUTHING OF A MEDIEVAL MOUND

493

of the lowland population pattern, probably related to

specific natural or man-made features – swamp-land or

road systems etc.

Lorenzo Marasco

3 Air photo survey to study the site

The new episode of research in this area started with the

XIVth International School in Archaeology, organised in

collaboration with the Culture 2000 project Europeanlandscapes: past, present and future (www.e-

landscapes.com). Within this project, in the spring of

2005, the University of Siena, in collaboration with

English Heritage and the international Aerial

Archaeology Research Group (AARG), conducted an

Aerial Archaeology Research School at Grosseto

Figure 3 Detail of the features, from an oblique air photograph taken in the summer of 2005.

During the School, through repeated flights in light

aircraft, oblique air-photo records were made of a

distinctive group of archaeological cropmarks, illustrated

in Fig.3 above. The features consisted of a triple

concentric circular enclosure with a fourth mark in the

centre and a fifth on the left-hand side of the second

enclosure. In addition, there were traces of a number of

parallel linear cropmarks, overlapping the enclosures.

Mapping of the new air-photo evidence against the

historical and technical national cartography (IGM

1:25.000 and CTR 1:10.000) revealed the that the closest

placename (less than 500 m away) was Podere Castellina,

now attached to an old agricultural building but possibly

preserving the memory of a former medieval castle

somewhere in the area. This interpretation could be in

keeping with the reading of the air photo data. The

circular enclosures – encompassing an area of almost one

hectare – could be interpreted as concentric ditches

and/or palisades. The marks inside and outside the

smallest enclosure could be related to buildings. The

linear features – visible also on the IGM 1:25.000

historical maps – are probably related to an ancient road

system.

Figure 4 GIS based interpretation (polygon) and hypothesis (line)

The mapping process permitted a better understanding of

the site and overcame the problem pointed out at the

beginning of this article – the absence of evidence on the

ground. Earlier examination of vertical air photographs

from 1954 had been successful in detecting the site but

the absence then of appropriate mapping procedures,

along with the use of a base-map at the relatively small

scale of 1:25.000, had shifted the site-positioning 150

metres to the north-east of the true location revealed by

the more recent studies.

4 Field-walking and DGPD survey

Ground-examination in 2005 brought an immediate

understanding of the high archaeological and historical

value of the site. The survey was carried out in the month

of September, immediately after ploughing and in good

lighting conditions, creating excellent archaeological

visibility and allowing the recovery of a large quantity of

artefacts. The first survey results showed that some of the

pottery could be dated to the early Middle Ages. But

bearing in mind the poor understanding of the material

culture of this period we felt the need for caution and

therefore organised a more intensive grid-collection

within 10 m by 10 m squares (Fig.5).

FROM SPACE TO PLACE

494

The investigation allowed us to confirm the first

evaluation regarding the chronological period and helped

in the general interpretation of the site. The pottery

studies permitted identification of the first phase of the

site as starting from the eighth century AD, with an

apparent cessation of occupation in the eleventh century.

Furthermore, ground survey was very helpful in revealing

the site’s distinctive morphology. On the ground it is

quite easy to recognise, in correspondence with the area

of the features seen on the air photographs, a slightly

higher area, roughly circular, rising up to a metre above

the surrounding terrain.

Figure 5 The grid layout for field-walking (within 10 m squares)

Following this we decided to make a full survey of the

area using a DGPS system to collect precise information

on the local morphology. The data was collected using a

Leica 500 device as the base station and a Leica 1200 as

the rover device, with sampling rate of 1 second. The

post-processing of the data was carried out by the

Geophysics Laboratory of the University of Bologna. The

result is a very detailed cloud-point representation,

interpolated using the circular krieging algorithm and

then imported into the GIS to facilitate data integration

and interpretation. The resulting DEM (Fig.7) shows

clearly the presence of a slightly raised area cut by a

number of deep plough-furrows.

5 Magnetic survey

The magnetic survey was carried out immediately after

the field-walking and artefact-collection from the

ploughed surface. These conditions are not inherently

favourable to this technique because they introduce noise

into the data, making the post-processing significantly

more complicated (Fig.6). The measurements have a

resolution of 1 m between the profiles and between 30

and 50 cm along the traverses. The surveyed area was 2

hectares in extent and corresponded to the main area of

the features visible on the oblique aerial photographs and

to the general extent of the artefact scatter.

Interpretation of the magnetic plot allowed us to

recognise a number of features, with a degree of detail

roughly similar to that of the oblique air photograph. The

magnetic map shows three concentric enclosures and

slightly below and to the left of the centre of the inner

enclosure in the centre a smaller circular one that can

probably be interpreted as a building.

Figure 6 Above, map of 2 hectares of magnetic data, clearly showing three enclosures and many other features. Below, detail of the central part of the magnetic map, showing the higher strength of the signal of the smaller enclosure and the large number of dipoles in this area.

Other potential features are represented by small dipoles,

higher in density inside and immediately outside the

smallest enclosure (Fig.6). These latter features are

difficult to interpret, mainly because of the low resolution

of the survey. Bearing in mind the particular nature of the

site – hypothetically that of a medieval castle mound –

this type of evidence could find parallels in other case

studies, perhaps relating to the existence of post holes in

the underlying deposits (Gaffney, Gater 2003; Tipper

S. CAMPANA, R. FRANCOVICH, L. MARASCO: REMOTE SENSING AND GROUND-TRUTHING OF A MEDIEVAL MOUND

495

Figure 7 Integrated analysis of the site

2004). To obtain a better understanding of the site it

would be useful, in the near future, to repeat the magnetic

survey, increasing the resolution between profiles to

between 50 to 20 cm.

Stefano Campana

6 Data integration and conclusion

On the evidence so far collected we feel confident about

our general interpretation. We have probably located the

first known lowland castle-mound in Tuscany.

The chronology suggested by the finds – from the eighth

to ninth centuries through to the eleventh century – is also

consistent with the data drawn from the air photographs,

magnetic mapping and DGPS survey (Fig.7). Taken

together, the various kinds of evidence point to features

that it is possible to interpret as a lowland timber castle

characterised by at least three concentric defensive

features, presumably ditches or palisades.

As is well-known from other parts of Europe, a mound or

motte of this kind is a typical form of medieval

fortification, consisting of a raised earthen mound,

resembling a small hill, usually artificial or at least

artificially enhanced and topped with a wooden or stone

structure. The earth for the mound would be taken from

the ditch around the motte itself and perhaps from other

ditches around the castle as a whole. The outer surface of

the mound might in some instances have been covered

with clay or strengthened with wooden supports

(Hingham, Barker 2004). This kind of castle, however,

can exhibit a wide range of variability.

In our case the aerial photographs show evidence that,

even without other information, we can interpret with

some confidence as ditches. The magnetic map is

superficially similar in appearance to the aerial

photograph, showing three circular traces. But we should

be carefully in drawing conclusions from this similarity –

aerial reconnaissance relies on phenomena that are quite

different from those involved in the interpretation of

magnetic data. Archaeologists are mainly used to

interpreting features through their shape and size. We

should bear in mind, however, that there is a significant

difference between the meaning of the two soil

measurements, the first related to the growth and colour

of the overlying crop, the second to the magneticproperties of the underlying deposits. While

acknowledging this difference there is a remarkable

degree of similarity between the air photo evidence and

the magnetic map. The magnetic measurements for the

smaller enclosure show a very high and consistent signal,

probably indicating the presence of a higher

concentration of organic material, perhaps related to the

former presence of a timber palisade or to a concentration

of organic or other rubbish thrown out from the central

enclosure.

The air-photo evidence in the central part of the mound,

possibly indicating a masonry building, is also reflected

in the magnetic map and even more so in the results of

FROM SPACE TO PLACE

496

the field survey – artefact collection in the central area

showed a high density of stones and mortar.

The available evidence allows us to interpret the site as

an early medieval fortified settlement – perhaps in

relationship to a curtis – starting from at least the ninth

century AD. Its main peculiarity is its fortress typology

and its lowland siting. Such a location should probably be

linked with lake of Scarlino and with the ancient road

system of the Aurelia. The settlement does not appear to

have lasted beyond the eleventh century, to judge by the

pottery and the absence of building materials that indicate

any kind of Romanesque stylistic tradition.

In conclusion, we should emphasise that without an

integrated approach it would never have been possible to

present such a rich and articulated interpretation of the

site. The isolated application of each prospection method

on its own would have revealed only some aspects of the

site, limiting our overall understanding of the evidence.

For instance the field-walking survey would have shown

a clear pottery concentration no more than 20 by 20 m

across. That evidence, on its own, could have been

interpreted as the remains of a very small settlement – a

completely different picture from the one-hectare timber

castle revealed by the several techniques in partnership.

Stefano Campana, Lorenzo Marasco

Acknowledgments

The authors are indebted to Dr. Salvatore Piro (ITABC –

CNR) and Dr. Iacopo Nicolosi (National Institute of

Geophysics and Vulcanology) for their invaluable

comments and criticisms on geophysical survey

techniques and data processing. Special thanks are also

due to Chris Musson for help with the translation into

English and for his valuable comments on the practice of

archaeological research, both in the air and on the ground.

Many researchers and students have collaborated, and are

still collaborating, in the Siena and Grosseto

archaeological mapping projects. Special thanks are due

to the team of the Landscapes Archaeology and Remote

Sensing Laboratories of the University of Siena at

Grosseto: C.Felici, A.Caprasecca, M.Corsi, B.Frezza,

M.Ghisleni, F.Pericci and E.Vaccaro.

References

BARTOLINI, E. PRANZINI, E. LUPIA PALMIERI, C.

CAPUTO 1977 C., Studi di geomorfologia costiera: IV L’erosione del litorale di Follonica, «BS Geol.I»,

96.pp.87-116.

CAMPANA S., 2005, Tecnologie GPS e Personal Data

Assistant applicate all’archeologia dei paesaggi,

“Archeologia e Calcolatori”, 16, , Firenze.

COSCI 2005, Ricerche aeree in Toscana, in MUSSON

C., PALMER R., CAMPANA S.

CHAPMAN H. 2001, Understanding and Using Archaeological Topographic Surveys – The “Error Conspirancy”, in Computing Archaeology for

understanding the past, Proceedings of CAA 2000,

BAR International Series 931, Oxford, pp.19-23.

CUCINI C., 1985, Topografia del territorio delle valli del Pecora e dell'Alma, in FRANCOVICH R. 1985, pp.

147-335.

FRANCOVICH R. (ed.) 1985a, Scarlino. I. Storia e territorio, “Ricerche di Archeologia Altomedievale e

Medievale”, 9/10, Firenze.

FRANCOVICH R., HODGES R. 2003 Villa to village. The transformation of the Roman Countryside in Italy, c.400-1000, Duckworth, London.

GAFFNEY C., GATER J. 2003, Revealing the buried

past. Geophysics for Archaeologists, Tempus

HINGHAM R., BARKER P. 2004, Timber castle, Exeter.

MARASCO L. forthcoming, Scarlino. Nascita e sviluppo di un castello medievale. L’indagine archeologica,

Firenze.

MUSSON C., PALMER R., CAMPANA S. 2005 In volo nel passato. Ricognizioni aeree e aerofotografia obliqua, Firenze, pp.328.

TIPPER J. 2004, The Grubenhaus in Anglo-Saxon England, Oxford