feb 112013

“New approaches to old issues: the application of predictive maps in archaeology.
A case study: modelling the location of Grosseto’s salt works from 900 BC to AD 1200.”
Medieval Settlement Research, 26.
Published in 2012

Carlo Citter, Antonia-Arnoldus-Huyzendveld (University of Siena – Italy)


As yet, we have no archaeological data about the salt works near Grosseto (Tuscany), but they must have been one of the main reasons for the town’s foundation and growth. However, the position of the salt works through time, and even their chronology, is still a matter of conjectures (see also the page Le saline tirreniche).
Grosseto was a small village around AD 700, that became a bishop-town (AD 1138) and, later, a Comune (13th century AD). The development of the Etruscan town of Rusellae in the 6th century BC, which is very close by on the hills to the north, could have some relationship to the exploitation of this precious resource.

The first unquestionable mention of salt works is in a chart of 1152 (terraticum salinarum). However, the main document is the charta libertatis of 1204, where the Aldobrandeschi are forced to grant the community of Grosseto half of all the salt revenues. This document informs us that the production of 1203 was 840 tons of salt. The 13th century seems a crucial period of intensive production. The salt of Grosseto was sold in Siena, Florence and Genua, and it was so famous to deserve a literary mention by medieval poets. Well known is the interest of Pisa in the salt revenues of the lagoon of Grosseto.
The salt masters of Siena declared in 1386 that the former salt works near Grosseto could not be used anymore, because the lagoonal environment had changed to freshwater. From the 15th century on, the new salt works were shifted south-west of Grosseto, along the Ombrone river, in a place close to La Trappola. Despite the small extension (1 ha), more than 800 tons of salt were produced here each year, until its abandonment in 1758.


Detail of the salt basins of La Trappola, and an overview of the tools in use.

The Grosseto plain has been reclaimed in the 19th and early 20th century by elevating the topsoil of the lower areas in the order of meters, making it impossible to field walk with success. We chose to evaluate the most promising location of the salt-works from the Roman period, or even earlier, until the high Middle Ages, through GIS spatial analysis with the use of hydrology tools. These can give us some indications for reducing a vast plain to small areas (no more than a few hectares each) whose potential is higher than anywhere else. These can be surveyed with geophysics, trenches and, in case of success, extended excavations.

The whole data set and the modeling procedures are explained in the publication. In order to model the possible location of the salt works, as was the goal of these operations, we had to consider the altitudes and the extension of the former lagoon, and moreover the feasibility of creating a channel to the sea, since salt water must flow into the area. The final results for the Roman and late medieval periods are shown in the figures.


The modeled extension and position of Grosseto’s salt works in Roman times (the cross hatched surface).

According to the modeled results, for the Roman period the effective potential extension for salt winning is around 5 hectares, whereas for the late medieval period it is ca. 3 hectares. According to our calculations, this implies for the Roman period a maximal production of about 460 tons of salt per production cycle, and for the Middle Ages of about 240 tons. We don’t know how much production cycles there were in a year, since we don’t know the salt winning technique that was used at the time, but presumably there were several.


Results of the GIS modeling: the inferred position of the historical salt works.

ott 082012


As the Albano lake and Monte Cavo were linked to the sun and to Jupiter, lake Nemi was related to the moon and to the triple goddess Diana. Still now during the summer, the full moon as seen from the town of Nemi is reflected in the lake, and about an hour later in the Tyrrhenian sea (that is the moon three times !).
During the “wake” of 21 august 2002, we observed that around 4.0 h. am, the image of the moon reflected in the water started to be visible close to Diana’s temple along the lake, under the steep wall of the town of Nemi. From that point on, the reflection has crossed the water in about an hour, reaching the opposite shore in a point below the town of Genzano. That night the clouds have hampered the observation of the moon reflected in the sea.

Lake Nemi WP_nemi_lake_from_town.jpg

The lake seen from the town of Nemi, with in the background a strip of the Tyrrhenian sea (photograph Caroline Lawrence).


Northern border of the Nemi lake; the remains of Diana’s sanctuary are ( just) visible in the lower right part of the photograph taken from Nemi town (photograph Caroline Lawrence).

Two painting of the Lake Nemi, one with the crescent moon reflected in the lake, the second with the sun reflected in the lake and the sea.

Enrico Coleman: Speculum Dianae – Lake Nemi Oil painting  - 1909

Enrico Coleman: Speculum Dianae – Lake Nemi
Oil painting, 1909

Verde e violaceo, cupo, muto, in mezzo al grande stormire dei boschi [...] Secondo le vicende della luce, il lago varia. Il suo verde si fa talvolta splendido e limpido come lo smeraldo; il suo violaceo si fa oscuro e vellutato come la foglia della viola tricolore”
G. D’Annunzio, Taccuini, 1897.

Sanford Robinson Gifford: Il lago di Nemi (1856-57) Toledo (Ohio), Museum of Art

Sanford Robinson Gifford: Lake Nemi (1856-57)
Toledo (Ohio), Museum of Art

Lake Nemi (1856-57), a work that Gifford painted for exhibit in New York while in Italy, is the first of his paintings to have the sun as a focal point of the painting using light and tone to unifying and simply the landscape. This was to become a trademark of his work. We can trace his fascination with the transfiguring effects of light on the natural landscape throughout the exhibits in such works as ‘A Gorge in the Mountains’ (1859) ‘Mansfield Mountain’ (1859) and ‘The Wilderness’ (1860).

Diana’s temple on Google Maps

See also the page on Alba Longa.

See also Caroline Lawrence‘s blogspot on a day around Albano lake, the 17th of september 2008.

set 152012

Andrea Locatelli (Rome, 1695 – 1741): “View of the Salt Pans near Ostia“, 89 x 137 cm.

salt pans WP_Locatelli_salt_pans

Recently this painting was sold to a private collector by the Matthiesen Gallery in London. From their website:

(..) In 1833 most of Ponte Galeria, formerly Campo Saline, was acquired by the Genoese Pallavicini family. Since this painting came originally from the collections of the Rospigliosi family, which from the end of the seventeenth century was closely allied with the Pallavicini, it is not improbable that the painting entered their collection in the nineteenth century when the latter acquired this property (..).
This Marine Landscape retains many obvious topographical features rare in Locatelli’s oeuvre which, for the most part, are fantasy classical landscapes. In the foreground we observe a few shepherds with animals grazing and, in the centre, the salt works with fishermen intent on their task. On the land there is a small warehouse used to store salt deposits. In front of this, a few figures are loading mules and horses with goods. This painting represents one of the finest examples of Locatelli’s view paintings, much rarer than his idealized landscapes.

The location must effectively be near Ostia, since at the time the Maccarese salt pans where not active any more. In the background one observes the unmistakable outline of the Colli Albano volcano, which is well visible from Ostia. The relief to the right could be that of Castel Porziano.
The view is to the east, so the sun is rising, probably in the summer (the tree might be a deciduous oak), the right season for salt extraction.
There are evident wooden structures to catch and conserve fish (the zigzag lines, like the lavorieri of the lagoon of Venice or the acconci of Puglia), and towards the little building there seem to be salt pans and mounds. The two functions often went together in the same plant, as until recently was the case in Comacchio (FE), which can clearly be seen on an image of Google Earth of 2005.


acconcio fishing system of Puglia


“lavoriero” of the lagoon of Comacchio (FE); foto Sargentini.


The salt works of Comacchio on an image of Google Earth of 2005: salt pans to the east and south, fishing ponds and “lavorieri” to the west and north.

See also the pages Ostia & Portus and Le saline tirreniche, and the article The quest for Grosseto’s original saltworks.