Tonnie_Rocca

Tonnie_Rocca

set 092017
 

Ostia was founded along the Tiber river and close to the sea. Each of these strategic conditions was lost over the centuries: the position near the sea through the gradual growth of the dune belt (see www.ostia-foundation.org/coastline/), and the position along the Tiber on the 15th of September 1557, as the result of an exceptionally high flood, which shortened the river course by cutting off the narrow meander. On this occasion the castle of Ostia, constructed only 60 years earlier by pope Julius II, became suddenly isolated from the Tiber.

Fiume morto-2
Fiume morto-4The remains of the cut-off river curve is called the Dead River (Fiume Morto) and can still be seen on an aerial photograph of 1911, and – if you know where to look for it – even on modern Google Earth images. The event was somewhat predictable, given the sharp curve of the river course near the castle in the decades before the catastrophe.

Until the end of the 19th century the remains were still visible in the landscape as a small lake. It was later filled in with materials from the excavations. Nowadays it requires some imagination to envision in the grassy fields one of the major rivers of Italy flowing alongside the Castle and the excavations of Ostia.

Fiume morto-3

Tonnie Huijzendveld (Arnoldus)

dic 202016
 

Author: Tonnie Huijzendveld (Arnoldus)

The coastal plain of Rome is characterized by two wide depressions that were occupied originally by ponds, the Stagno di Maccarese and the Stagno Ostiensis, separated by the Tiber river (figure 1).
Historical salt works have been established in each of the marshes.

Fig. 1 - Simplified topography and geology of the coastal plain of Rome; C, harbour basin of Claudius; T, harbour basin of Trajan; F, “Fiume Morto”, the river course before 1557 A.D.; with a star are marked the known historical salt works.

Fig. 1 – Simplified topography and geology of the coastal plain of Rome; C, harbour basin of Claudius; T, harbour basin of Trajan; F, “Fiume Morto”, the river course before 1557 A.D.; with a star are marked the known historical salt works.

The salt works of Ostia
The Roman age salt works of the Stagno Ostiensis have not been located exactly nor excavated, so we don’t even know their layout. It is only possible to presume that the warehouses and wharfs of the harbour situated in the suburban zone of Ostia, along the later filled in meander of the Tiber, were the hubs from which the salt was transported to Rome.
One of the most ancient salt deposits is recognizable in the late medieval building called Casalone, now incorporated in the modern township and close to the abandoned river course. After the cut off of the meander in the sixteenth century, salt storage occurred in the Magazzino de Sali, which is now the Museum of Ostia Antica.
The exact size of the lagoon of Ostia was partly defined thanks to recent archaeological excavations, which pinpointed most of the banks of the lagoon in the Roman period (Pannuzi, 2013).

The Romans considered Ostia their first colony and they attributed its founding for the purpose of salt production to their fourth king, Ancus Marcius (second half of the 7th century B.C.), but no archaeological proofs have been found for this. In fact, the soil of Ostia (not even the Castrum, which is the first “urban” development), has so far delivered no findings dating back to the time of the Kings.

Fig. 2 The salt works of Ostia indicated on the map of Amenduni 1884; also visible is the oxbow lake, remnant of the river course abandoned during the flood of 1557.

Fig. 2 The salt works of Ostia indicated on the map of Amenduni 1884; also visible is the oxbow lake, remnant of the river course abandoned during the flood of 1557.

The paleo-environmental reconstruction of Bellotti et al. 2011 could clarify the discrepancy between archaeological and historical sources on the origin of Ostia. The Authors state that initially the coastal barrier belt separating the marsh of Ostia from the sea would have been too narrow and insecure against storms to support a permanent human occupation. Therefore, in the 7th century B.C. there would have been only an outpost, with the aim of controlling the strategic river mouth and, eventually, to set up the first salt works in the marsh. In fact, the data of pollen and molluscs of a drilling core indicate around 600 B.C. a sudden intrusion of sea water, which would have allowed salt extraction. It is not clear if this is a natural event or a man induced breakthrough of the barrier belt.

According to this hypothesis, only around 450 B.C., when the cusp had expanded more than 1 km into the sea following a progradation rate of about 5–6 m/year, the sandy substrate was supposedly large and safe enough to set up a fortified camp (the Castrum of Ostia) and to further develop the salt works.

The salt works of Ostia have continued to function until the nineteenth century, and are indicated on a map of 1884 (figure 2) and visible on an aerial photograph taken from a balloon in 1911 (figure 3).

Fig. 3 - Part of the salt works of Ostia visible on an aerial photograph taken from a balloon in 1911; to the left the abandoned river bend of the Fiume Morto; an arrow indicates the original stream direction; modified from Shepherd 2006.

Fig. 3 – Part of the salt works of Ostia visible on an aerial photograph taken from a balloon in 1911; to the left the abandoned river bend of the Fiume Morto; an arrow indicates the original stream direction; modified from Shepherd 2006.

At the time, the decay of the coastal plain was total: it is described in 1831 as an unhealthy marshy environment. The 19th century painting of Jean Baptist Adolphe Gibert sets this atmosphere rather well (figure 4).

Fig. 4 - Jean Baptiste Adolphe Gibert (1803-1889), painting of the salt marshes of Ostia.

Fig. 4 – Jean Baptiste Adolphe Gibert (1803-1889), painting of the salt marshes of Ostia.

It is evident from the images that, at least in later times, these salt works were structured in serial basins, as described by Georgius Agricola in 1556, who recommends to build salt pans by evaporation “near that part of the seashore where there is a quiet pool, and there are wide, level plains which the inundations of the sea do not overflow”.

According to the indications, the brine is collected into shallow ponds and allowed to evaporate in the sun. A stepped process along a series of interconnected basins separates the undesirable substances from the fine salt. The basin should be moderately deep depressions, surrounded by embankments and separated by ditches with adjustable openings. The gentle drop down applied to the complex would allow the water to flow from one basin to another. The low tidal range of only 30-40 cm, common to all coastal plans along the Tyrrhenian Sea, should make it impractical, but not impossible, to use the high tide for letting the marine waters enter the salt basins.

The Maccarese saltworks
An important environmental event that occurred, before or during the Etruscan period, with an almost stable sea level, is the transformation of the water of the Maccarese lagoon from fresh into salt/brackish (naturally and/or artificially promoted?), enough to allow the construction of salt works. This change is recorded to have occurred after 910-800 cal B.C. (calibrated 14C dating) by Giraudi 2004. The cause of this transformation should have been the re-opening of the connection with the sea.

Following this “environmental revolution”, the area of Maccarese became an important centre of salt production under both Etruscan and Roman domination. Although mentioned by the ancient sources, the Etruscan salt pans have never been found. After the conquest of Veio in 396 B.C., the salt works came under Roman control and were used under the name Campus salinarum romanarum throughout the Republican and Imperial period.

The salt pans of Maccarese were exploited at long, and are mentioned in several documents at least until the end of the fifteenth century, under the names Campus Maior, Campus salinarius or Campus Salinus Maior (Morelli & Forte 2014).
Recent trench prospection and excavation campaigns (Grossi et al. 2015) have brought to light Roman imperial salt works, composed of a complex of canals dug into the earth, used to channel and distribute salt water from the Maccarese Pond. Connected to the salt extraction systems was a structure composed of a one-kilometre string of 1439 amphorae inserted upright into the muddy substrate (fig. 5).

Fig. 5. Principal features of the Maccarese hydraulic system (1st century A.D.) overlain on the map of Amenduni 1884; a dotted line marks the historical lagoon shore. D, amphorae dam; W, ground canals departing eastward from the main walled channels; yellow squares mark the position of the masonry canals with sluices. Modified from Grossi et al. 2015.

Fig. 5. Principal features of the Maccarese hydraulic system (1st century A.D.) overlain on the map of Amenduni 1884; a dotted line marks the historical lagoon shore. D, amphorae dam; W, ground canals departing eastward from the main walled channels; yellow squares mark the position of the masonry canals with sluices. Modified from Grossi et al. 2015.

The row of amphorae, datable between the Augustan period and the middle of the first century A.D., composed the framework of an earthen dam and was crossed by two canals in cement with opus reticulatum facing, each about 25 m long and provided with a sequence of two sluices. These canals have a characteristic funnel shape, with the opening to the west, which confirms their function as collectors of water from the lagoon (figure 6).

Fig. 6 - Aerial view of one of the funnel-shaped masonry channels crossing the earthen dam with the string of amphorae. Standing out is the white travertine of the two sluices (from Morelli & Forte 2014).

Fig. 6 – Aerial view of one of the funnel-shaped masonry channels crossing the earthen dam with the string of amphorae. Standing out is the white travertine of the two sluices; West is on the right hand side of the image (from Morelli & Forte 2014).

From the brick channels branch off to the east two long canals dug into the earth. The system is completed by two ground channels or “basins” reinforced with rows of wooden poles (guaranteeing walkways), located parallel on both sides of the amphorae dam, and probably intended as water collectors. Their depth is shallow, max. 0,40-0,50 m, which coincides with the tidal range of these coastal plains.

The layout of the system suggests that the dam and the two masonry canals with sluices allowed to control the salt water flowing from the Maccarese Pond, which was then distributed over the vast territory behind the dam through canals dug into the earth. One or more times a year, from the start of the dry season, the salt water would have been let in during high tide. Then the sluices were closed, thus isolating, together with the amphorae dam, the system temporarily from the main body of the lagoon. Behind the dam, a shallow water surface would spread out over the flat areas between the canals, where salt concentrated and could be harvested.

Such a single-cycle process, without the use of interconnected basins to gradually purify the brine, would imply that these salt works produced unrefined marine salt. These salt works might be similar to the system is described by Rutilio Namaziano (I, 475-486) in the fifth century AD near Volterra.

For service and salt storage activities, two building complexes attributable to the late-Republican and Imperial age, have been identified along the Via Portuensis. In one of them an epigraph was found datable to 135 A.D., of a dedication to Neptune made by two men identified as conductores campi salinarum romanarum, i.e. Roman salt work contractors (Morelli & Forte 2014).


References

  • Agricola, Georgius, 1556, De Re Metallica, http://www.gutenberg.org/cache/epub/38015/pg38015.txt
  • Amenduni, G., 1884, Sulle Opere di Bonificazione della Plaga litoranea dell’Agro Romano. Roma, Tipografia Eredi Botta.
  • Bellotti, P., Calderoni, G., Di Rita, F., D’Orefice, M., D’Amico, C., Esu, D., Magri, D., Preite Martinez, M., Tortora, P., Valeri, P., 2011, The Tiber river delta plain (central Italy): Coastal evolution and implications for the ancient Ostia Roman settlement, The Holocene 2011, 21, pp. 1105-1116. DOI: 10.1177/0959683611400464.
  • Giraudi C., 2004, Evoluzione tardo-olocenica del delta del Tevere. Il Quaternario, Italian Journal of Quaternary Sciences, 17 (2/2), pp. 477-492.
  • Grossi M. C., Sivilli S., Arnoldus-Huyzendveld A., Facciolo A., Rinaldi M.L., Ruggeri D., Morelli C., 2015, A complex relationship between human and natural landscape: a multidisciplinary approach to the study of the ancient saltworks in “Le Vignole-Interporto” (Maccarese, Fiumicino – Rome); in Archaeology of Salt. Approaching an invisible past, Robin Brigand, Olivier Weller (eds), Sidestone Press, pp. 83 – 101.
  • Morelli, C., Forte, V., 2014, Il Campus Salinarum Romanarum e l’epigrafe dei conductores, Mélanges de l’École française de Rome – Antiquité, 126-1 | 2014, URL: http://mefra.revues.org/2059; DOI: 10.4000/mefra.2059
  • Rutilio Namaziano, De redito suo. http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Rutilius_Namatianus/text*.html
  • Pannuzi, S., 2013, La laguna di Ostia: produzione del sale e trasformazione del paesaggio dall’età antica all’età moderna. Mélanges de l’École française de Rome – Moyen Âge, 125-2, http://mefrm.revues.org/1507; DOI: 10.4000/mefrm.1507
  • Shepherd, E. J.,2006, Il rilievo topofotografico di Ostia dal pallone (1911), Archeologia aerea 2 (2006), pp. 15-38. (The Topographical Survey of Ostia from a Balloon, 1911, English translation by David Wilkinson, 2012; https://www.academia.edu/4314559/).

This text has been published under a Creative Commons License CC BY-NC-SA 4.0. Feel free to publish it on your websites, blogs… under the following conditions: You must give appropriate credit, mention the author and provide a link to this original publication and to the license indicated above. You may not use the material for commercial purposes.

dic 012016
 

Author: Tonnie Huijzendveld (Arnoldus)

The two breakwaters
Pope Pius II in his Commentarii (1614[1]) wrote:“Emperor Claudius built a harbour protected right and left by jetties, with a mole at the entrance where the sea is deep.”

The harbour basin of Claudius is located about 2 km north of Ostia, near the Roman town of Portus (Figure 1).

Fig. 1 - The extension of the harbour basin of Claudius, with in black the exposed part of the moles and in red the "hidden" parts; a dotted line indicates the Roman coast.

Fig. 1 – The extension of the harbour basin of Claudius, with in black the exposed part of the moles and in red the “hidden” parts; a dotted line indicates the Roman coast.

Fig. 2 - Nero’s coin showing the harbour basin of Claudius; from www.ancientportsantiques.com/a-few-ports/portus/#5. Source: Oleson, 2014 (British Museum); the sea is on top of the image, north is to the right.

Fig. 2 – Nero’s coin showing the harbour basin of Claudius; from www.ancientportsantiques.com/a-few-ports/portus/#5. Source: Oleson, 2014 (British Museum); the sea is on top of the image, north is to the right.

Construction commenced in A.D. 42 and was completed by Nero in the year 64. On the occasion of the inauguration, the emperor authorized the production of a series of bronze coins depicting details of the port on the reverse. The harbour of Claudius is depicted in great detail, with merchant ships floating in the sea, the two breakwaters curving on either side of the coin, and the sea entrance with a central lighthouse and statue (Figure 2).

Even today, part of the southern breakwater is preserved, but it is hidden under the Tiber embankment. The landside part of the northern pier, instead, is well exposed at the surface and visible over a length of ca. 750 meters along the Via dell’Aeroporto di Fiumicino and behind the Museo delle Navi (Figure 3). This stretch was excavated on the occasion of the construction of the new airport of Rome in the 1960’s.

ig. 3 - Part of the northern mole of the harbour of Claudius exposed behind the Museo delle Navi of Fiumicino.

Fig. 3 – Part of the northern mole of the harbour of Claudius exposed behind the Museo delle Navi of Fiumicino.

Further to the west no traces of the breakwater can be seen at the surface level. In fact, trenches excavated under the auspices of the Soprintendenza Archeologica di Ostia uncovered no remains of this breakwater, even at the depth of several meters. The disappearance of this breakwater is due to the strong growth of the dune belt in historical times, particularly in the last centuries. The moles of the harbour of Claudius were covered by sandy sediments (see contribution on the coastline of Ostia), and the real size and orientation of the harbour basin were forgotten for centuries.

A forgotten outline
Let’s get a short historical overview of how the basin of Claudius has been depicted. In the images of the 16th and 17th centuries the basin was always (correctly!) shown to be wide, delimited to the north and south by breakwaters curved toward the western entrance, where the lighthouse island was located (Figure 4).

Fig. 4 - Reconstruction of the harbour basins of Claudius and Trajan by Antonio Labacco 1552-67, tav. 29. Distances are indicated in “canne romane” (1 canna = ca. 2,234 m). The orientation is E-W inverted.

Fig. 4 – Reconstruction of the harbour basins of Claudius and Trajan by Antonio Labacco 1552-67, tav. 29. Distances are indicated in “canne romane” (1 canna = ca. 2,234 m). The orientation is E-W inverted.

But from the first half of the 19th century we begin to see plans of the harbour showing a much smaller basin, and with the central axis rotated 90 degrees towards an entrance in the north, and with the lighthouse to the left of that entrance. This mistaken reconstruction has been unfortunately preserved even in recent publications (see Figure 5[2]). The cause of this misinterpretation is almost certainly the sheer magnitude of deposits which covered the structures during the coastline advancement of the last centuries.

Fig. 5 - Erroneous reconstruction of the harbour basin of Claudius, with a reduced size and a northern main entrance; modified from Testaguzza 1970, p. 40.

Fig. 5 – Erroneous reconstruction of the harbour basin of Claudius, with a reduced size and a northern main entrance; modified from Testaguzza 1970, p. 40.

From the 19th through the first half of the 20th century, this wrong reconstruction was generally accepted. In the 1960s it was called into question specifically by Castagnoli and Giuliani[3]. Aerial photographs, among other things, led these scholars to return to the former hypothesis: a large E-W oriented basin. But even then the size of the harbour was underestimated, as was later discovered.

Return to a former idea.
Only in the last decade a series of deep drillings (Figure 6) have confirmed, without a doubt, that the basin is indeed east-west oriented and that it juts out farther into the sea than previously suspected: the distance between the inland margin (Monte Giulio) and the lighthouse island is about 2 km.

Fig. 6 - A deep drilling in action over the pier remains (2005).

Fig. 6 – A deep drilling in action over the pier remains (2005).

Fig. 7 - The drilling data collected until 2007 and their interpretation overlain on a photo mosaic of 1911; red diamonds indicate structures encountered in the drillings; the N-S road is the modern Viale Coccia di Morto.

Fig. 7 – The drilling data collected until 2007 and their interpretation overlain on a photo mosaic of 1911; red diamonds indicate structures encountered in the drillings; the N-S road is the modern Viale Coccia di Morto.

Remains of structures were encountered in the drillings executed between 2004 and 2007, only from a depth of several meters on, being covered by dune and marine sediments (Figure 7).

The buried remains of the lighthouse island and the final parts of both piers are located to the west of the Viale Coccia di Morto of Fiumicino. The extremity of the southern breakwater is under the Leonardo Da Vinci Rome Airport Hotel (a former glass factory) along the Via Portuense, and the lighthouse island is below the junkyard to the north of the Via della Foce Micina opposite the Via dei Capitoni.

Fig. 8 - Reconstruction of the outline of the piers, the lighthouse island and the entrances of the Claudian harbour, based upon drilling data collected between 2004 and 2007.

Fig. 8 – Reconstruction of the outline of the piers, the lighthouse island and the entrances of the Claudian harbour, based upon drilling data collected between 2004 and 2007.

The modern reconstruction shows two protruding moles and a lighthouse island, separated by evident entrances[4] (Figure 8). A third, narrower entrance (probably only a channel) was demonstrated to exist between the northern pier and Monte Giulio[5].

It is very interesting that the various distances indicated by Antonio Labacco[6] on a reconstructive map of the 16th century turned out to be approximately correct (see Figure 4). The collected data have also been overlain, as well as possible, on a (digitally stretched) image of a fresco of A. Danti of 1582 (Figure 9) which demonstrates not only the reliability of this fresco but also the visibility, at the time, of the remains of the lighthouse island and the mole extremities still in the sea, before their burial by the sediments of the advancing coast.

Fig. 9 - In red lines the outline of the Claudian harbour overlain on a digitally stretched image of the fresco of A. Danti of 1582 (Vatican Museum).

Fig. 9 – In red lines the outline of the Claudian harbour overlain on a digitally stretched image of the fresco of A. Danti of 1582 (Vatican Museum).

Contemporary writers confirm the visibility of the ruins of the lighthouse (Figure 10) in the sea. Giuliani mentions Biondo Flavio, who on that subject writes in 1558: “We still see a good part of this tower standing, although there is not much left of the marble with which it was covered[7]”. But it is Pio II, writing in 1614, who conveys the most useful information: “There are still traces of this tower which can be seen from far out at sea. Everything else has perished utterly.[8]

Fig. 10 - One of the over 20 images of the lighthouse known from Ostia and Portus (mosaic in statio 46 on the Square of the Corporations, Ostia)

Fig. 10 – One of the over 20 images of the lighthouse known from Ostia and Portus (mosaic in statio 46 on the Square of the Corporations, Ostia)

Two different stretches
In the drilling cores executed along the outer stretches of both piers, no hydraulic mortar was encountered, only large blocks of basalt and lithoid tuff embedded in coarse sand (Figure 11), forming a ridge-like rubble mound with a base width of at least 60 meters.

Fig. 11 – The main stone types composing the rubble mounds of the moles and lighthouse island: from left to right: basalt, red lithoid tuff and the same blackened from long immersion in sea water.

Fig. 11 – The main stone types composing the rubble mounds of the moles and lighthouse island: from left to right: basalt, red lithoid tuff and the same blackened from long immersion in sea water.

This suggests that the mole was constructed by piling stones on the seabed, which lines up with Pliny the Younger’s description of the construction of the harbour at Civitavecchia[9]: “The left arm of this port is defended by exceedingly strong works, while the right is in process of completion. An artificial island, which rises at the mouth of the harbour, breaks the force of the waves, and affords a safe passage to ships on either side. This island is formed by a process worth seeing: stones of a most enormous size are transported hither in a large sort of pontoons, and being piled one upon the other, are fixed by their own weight, gradually accumulating in the manner, as it were, of a natural mound. It already lifts its rocky back above the ocean, while the waves which beat upon it, being broken and tossed to an immense height, foam with a prodigious noise, and whiten all the surrounding sea.”

In the westernmost drillings the base of the northern breakwater has been found at a depth of 15-16 meter from the surface. Furthermore, it was found that the level of the sea bed directly beneath the structure is deeper than the surrounding area, with a difference of up to two meters. We may presume that this is due to the weight of the stones sinking into the soft sea bottom, a process that may have started from an early phase of the construction on. But there is more. De Graauw[10] shows how modern, loosely-piled-up breakwaters undergo a lowering of the top and a widening of the base due to wave action, transforming it from an emerging into a submerged mole. This usually happens in a later phase.

The gradual sinking of the base and lowering of the top of the rubble mounds, combined with the accumulation of sandy sediments due to the changing coastline, helps us to understand why the top of the remains are found several meters below the surface. We must also keep in mind that when the remains were first revealed in the waters close by the advancing coastline, people may have taken stones away from the moles for reuse elsewhere. As noted above, even today the inland part of the northern breakwater is well preserved. Testaguzza has given us an elaborate description of the structure. It is composed of several stretches made with different construction techniques: whole square blocks or mixed layers of concrete, tuff stones, brick fragments and mortar (Figure 12).

Fig. 12 - The western extremity of the exposed part of the northern mole, view to W; Testaguzza 1970 p. 85.

Fig. 12 – The western extremity of the exposed part of the northern mole, view to W; Testaguzza 1970 p. 85.

It has been shown that the western extremity of this construction rests upon a sea bed at a depth (in Roman times) of about 7.5 meters[11]. This inland stretch was probably constructed, according to the indications of Vitruvius, with wooden formworks filled with hydraulic mortar and stones (Figure 13), eventually resting on top of a rubble mound. It would have been built out from land, using lorries moving over the top of the pier above sea level[12].

Fig. 13 - Concrete reinforced with timber, a construction type possibly used for the exposed part of the northern breakwater; from www.ancientportsantiques.com/a-few-ports/portus/#5.

Fig. 13 – Concrete reinforced with timber, a construction type possibly used for the exposed part of the northern breakwater; from www.ancientportsantiques.com/a-few-ports/portus/#5.

The most recent drillings, executed within the Airport of Fiumicino on behalf of the Soprintendenza Archeologica di Ostia, are confirming the direction and base width of the “hidden” part of the northern breakwater as hypothesized earlier by Morelli et al.

Our current hypothesis explaining the difference in preservation of the two stretches of the northern breakwater of the harbour of Claudius is a difference in construction technique: the inner stretch made from caissons filled with hydraulic mortar and stones, against the seaward part made only of stones loosely piled upon the sea bed. The abruptness of the transition between the two stretches, proven to occur at a distance of less than 50 meters, is one of the arguments in favour. But not everything is resolved and understood, e.g. why didn’t we find, at least up to now, any traces of the arches indicated on the coins along the northern pier?


Notes:
[1] Original text in English: http://www.ostia-antica.org/~atexts/pius.htm.
[2] Testaguzza O., 1970 – Portus, Illustrazione dei Porti di Claudio e Traiano e della Città di Porto a Fiumicino; Julia Editrice, Roma.
[3] Giuliani C.F., 1996 – Note sulla topografia di Portus; in: Manucci V. (eds), 1996, Il Parco Archeologico Naturalistico del Porto di Traiano; Ministero per i Beni Culturali Ambientali, Soprintendenza Archeologica di Ostia, pp. 29-44.
[4] Morelli C., Marinucci A, Arnoldus-Huyzendveld A., 2011 – Il Porto di Claudio: nuove scoperte, in Portus and its Hinterland, recent archaeological research, Simon Keay & Lidia Paroli (eds), Archaeological Monographs of the British School at Rome, pp. 47-65.
[5] Goiran J.-Ph., Salomon F., Tronchere H., Carbonel P., Djerb H., Ognard C., 2011 – Caractéristiques sédimentaires du bassin portuaire de Claude: nouvelles données pour la localisation des ouvertures, in Keay S., Paroli L. (a cura di), Portus and its Hinterland, Archaeological Monographs of the British School at Rome: 31-45.
[6] Labacco A. (1552-67) – Libro appartenente a l’architettura nel quale si figurano alcune notabili antiquità di Roma. Roma, Antonio dall’Abacco.
[7] “di questa torre ne veggiamo insino ad hoggi una buona parte in pie, se non che ne sono stati tolti i marmi, dei quali ella era incrustata”
[8] “ancora rimangono vestigi della torre le quali si vedono là nel mare; tutti gli altri monumenti sono periti interamente”
[9] Letters LXXI; translation from https://www.gutenberg.org/files/2811/2811-h/2811-h.htm#link2H_4_0071.
[10] De Graauw A., http://www.ancientportsantiques.com/ancient-port-structures/failure-of-rubble-mound-breakwaters-in-the-long-term/
[11] Goiran Jean-Philippe, Hervé Tronchère, Ferréol Salomon, Pierre Carbonel, Hatem Djerbi, Carole Ognard, 2010 – Palaeoenvironmental reconstruction of the ancient harbors of Rome: Claudius and Trajan’s marine harbors on the Tiber delta, Quaternary International 216 (2010) pp. 3-13.
[12] De Graauw A., http://www.ancientportsantiques.com/a-few-ports/portus/#5.

This text has been published under a Creative Commons License CC BY-NC-SA 4.0. Feel free to publish it on your websites, blogs… under the following conditions: You must give appropriate credit, mention the author and provide a link to this original publication and to the license indicated above. You may not use the material for commercial purposes.

dic 012016
 

Author: Tonnie Huijzendveld (Arnoldus)

The double arch of the coastline of the Campagna Romana is made up of littoral barriers connecting the rocky protrusions of Ladispoli and Anzio. In the centre, the regularity of alignment is interrupted by the river cusps of the Tiber and the Fiumicino channel (Figure 1).

Fig. 1 - The present coastline of the Campagna Romana.

Fig. 1 – The present coastline of the Campagna Romana.

Nowadays the sea is distant a few kilometres from the ancient city of Ostia. Evidence from classical sources, however, reveal that in Roman times the sea was actually very close by. Minucius Felix, for example, gives an eyewitness account of a walk from Ostia to the sea in the 2nd/3rd century A.D. After a vivid description of the beach and the sea, he writes: “Let us sit down on that rocky mole projecting into the sea, which has been made to protect the baths”. So obviously at the time the sea was not only close by, but also invading the coast and threatening the buildings of Ostia (Figure 2). This process is confirmed by an A.D. 238 epigraph which mentions stone blocks arranged as a protection of the seaward side of the Via Severiana.

Fig. 2 - Partial plan of the excavations of Ostia Antica, with the location where Minucius Felix was probably sitting when he described the sea.

Fig. 2 – Partial plan of the excavations of Ostia Antica, with the location where Minucius Felix was probably sitting when he described the sea.

Slightly more to the south was the Villa Laurentum, whose seaside position was described by Pliny the Younger in the 1st/2nd century A.D.

The position of the coast in the early centuries A.D., and, more generally, the original configuration of the coastal belt, has been masked by dune sand and alluvial sediments of the Tiber. Let me go back farther in time, and explain shortly the mechanism of coastline withdrawal and advancement, and from that viewpoint the environmental history of the coastal plain of Rome. These processes have been investigated mainly through deep drillings, followed by analysis of the core contents and radiocarbon dating.

Generally, the position of a coastline is determined by two factors: 1) the marine water level; 2) the quantity of sediment that is transported to the sea by the rivers. Geological research has proven that until about 5,000 years ago, the marine level played a major role in determining the position of the coastline: between ca. 17,000 and 5,000 years ago, the sea has gradually risen from about minus 125 meters to a stable level not dissimilar from today. This process of “drowning of the beach” implies an inland movement of the coastline . It is generally accepted that this marine rise was due to the melting of the polar ice caps after the end of the last great glacial period of 20,000 years ago. Small sea level variations have also occurred afterwards, e.g. in the first centuries A.D. the sea level was still ca. 1 meter lower than today. After the “great prehistorical sea level rise”, the coastline position has been mainly governed by the quantity of sediment carried by the rivers. In this case, just how does coastline expansion or withdrawal work?

The dunes of the coastal belt are composed of a series of beach ridges, each the final product of a coastal barrier formed initially on the seabed under the influence of waves. Each barrier has migrated slowly inland, to ultimately be welded to the coastline. The sandy material that makes up these sediments, was transported first by the rivers to the sea, and then by marine currents back to the shoreline. The sand suspended by the waves that reach the shore area is deposited on the beach, and then partly removed during the next withdrawal. If the successive wave is very strong, the sediment is completely eroded, and we are witnessing the beginning of a new cycle. The beach ridges may instead survive where there is an abundance of solid load of the rivers, and thus of the sea (Figure 3). In that case a sedimentary sequence is formed composed horizontally of an alternating series of dunes and interdunal depressions, which reflects the cyclic nature of the processes (Figure 4).

Fig. 3 - Scheme of the advancing delta with a stable sea level; the arrows indicate the position of the photograph of figure 4.

Fig. 3 – Scheme of the advancing delta with a stable sea level; the arrows indicate the position of the photograph of figure 4.

Fig. 4 - Trench wall in the “recent dunes” of the coastal plain of Rome. The growth occurred horizontally, in a sequence of large bands developing seawards, here from left to the right.

Fig. 4 – Trench wall in the “recent dunes” of the coastal plain of Rome. The growth occurred horizontally, in a sequence of large bands developing seawards, here from left to the right.

During recent investigations, the Roman beach has been revealed in several trenches excavated for the Soprintendenza Archeologica di Ostia (Figure 5).

Fig. 5 – A Roman beach intercepted in a trench north of Portus.

Fig. 5 – A Roman beach intercepted in a trench north of Portus.

We have seen how the sediment load of the river, the strength and direction of the marine currents and the force of the waves in the shore area are in a delicate balance, which in the long run can lead to an increase, to a standstill or to a withdrawal of the coastline. Thus the intensity of river discharge and inundations, determined by climatic conditions or by erosion in the watershed, becomes a potential factor in the shoreline evolution.

A challenging and unitary model on the development of the strand plain of the coastal area of Rome over the last millennia was provided by Bellotti et al. 2011 (Figure 6).

Fig. 6 - The main changes of the Tiber river mouth location during the strand-plain evolution (modified from Bellotti et al. 2011).

Fig. 6 – The main changes of the Tiber river mouth location during the strand-plain evolution (modified from Bellotti et al. 2011).

The several phases of migration of the Tiber are recorded by the different positions of the delta cusp. In the first phase, from ca. 3,000 b.C. until the 8th / 7th b.C., a cusp spread out over the entire area from Capo Due Rami to the place of the later imperial harbours, and unto the outer margin of the Stagno di Ostia. The transition to the second phase coincided with the sudden migration of the Tiber to the south, at first flowing into the Stagno Ostiensis and later breaking through the dune belt near future Ostia.

With the opening of the channel of Trajan (early 2nd century A.D.) a new complex system of delta progradation developed, with two river branches active almost simultaneously (the third phase). The process coincided with the frequent flooding of the Tiber; in Roman times about thirty floods were recorded. The advance of the coastline was initially slow, then of greater magnitude: about half of the advancement occurred from the 16th century A.D. on (Figure 7).

Fig. 7 - Advance of the coastline near Ostia in historical times; numbers indicate years A.D.

Fig. 7 – Advance of the coastline near Ostia in historical times; numbers indicate years A.D.

It was calculated that the average progradation between the 15th and 20th centuries has been 7.5 m/year. The coastline of 1570 A.D. is well documented through the position of the Torre Alessandrina along the canal of Fiumicino and the Maschio di San Michele along the Tiber. Although the above-mentioned environmental changes were strictly controlled by the local conditions, they also reflected rapid worldwide climatic changes. So the 3rd century A.D. erosion phase reveals a warm climate episode, characterized by a decrease of the Tiber floods, whereas the progradation of the last 500 years coincides with a colder climatic phase (the ‘Little Ice Age’) and the registration in the coastal belt of Rome of the highest and strongest floods ever.

Based upon the drilling data, the aforementioned authors have developed an interesting hypothesis on the foundation and growth of Ostia: around 2600 years ago the Stagno Ostiense was affected by a sudden environmental change through the input of sea water, which transformed the basin from lacustrine to brackish. This transformation coincided chronologically with the period of foundation of Ostia according to tradition. We do not know whether the sudden change was natural or due to human influence. At any rate, the width of the dune belt was too small to accommodate a real city, as Ostia was later to become. The hypothesis is that, at the time, it was only an outpost, possibly related to salt production.

The delta advanced seawards very quickly, at an estimated progradation rate of 5 – 6 m/year, so that by the 5th / 4th century b.C. it was almost fully developed. The hypothesis is that by then the dune belt was wide enough to allow the foundation and expansion of the city of Ostia. It may sound strange, but examples of advancing coastlines are scarce nowadays. I know of only one expanding beach in Italy, to the south of Grosseto in Tuscany. The present-day tendency is instead an overall retreat of the beach. This is not so much due to a rise of sea level, which has been only 12 cm in the last century, but mainly to the scarcity of sediment transported by the rivers to the sea. This can be considered to be a condition inverse to the abundance of river bed load available in the centuries before.


Notes:

Fig 2: Modified from www.ostiaantica.beniculturali.it
Fig. 3: Bellotti P., Calderoni G., Di Rita F., D’Orefice M., D’Amico C., Esu D., Magri D., Preite Martinez M., Tortora P., Valeri P., 2011, “The Tiber river delta plain (central Italy); Coastal evolution and implications for the ancient Ostia Roman settlement”, in the Holcene 2011 21: 1105, originally published online 26 May 2011 DOI: 10.1177/0959683611400464
Fig. 6: Modified from Dragone F., Maino A., Malatesta A, & Segre A.G., 1967 – Note illustrative della C.G.I. alla scala 1:100.000. Foglio 149 (Cerveteri). Serv.Geol.d’It., pag. 63

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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)

ABRIDGED VERSION

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.

WP_saline_grosseto_1500_1750_detail

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.

WP_Roman_saltworks_detail

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.

WP_Grosseto_salt_works

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

ott 082012
 

DIANA’S MIRROR

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).

WP_temple_Diana.jpg

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 222012
 
Macine WP_villaggio_macine_panorama

I pali sporgenti del Villaggio delle Macine visibili al margine del lago Albano, agosto 2012 (foto Matteucci)

Lungo il lago Albano nel 1984 sono stati rinvenuti i resti del “Villaggio della Macine”, un insediamento della media età  del bronzo di ca. 4000 anni fa. Il nome deriva dalla grande quantità  di macine in pietra recuperate. Si suppone che l’abitato sia stato abbandonato non oltre il XV secolo a.C., in seguito ad un innalzamento del livello del lago. Campagne di scavo archeologico si sono svolte nel 2001 e nel 2009 (info Wikipedia).

Dovuto all’attuale abbassamento del lago di ca. 1 metro ogni 3 anni, i pali sporgenti sono ben visibili. Questi mutamenti del livello delle acque sarebbero resi possibili dalla presenza, sotto la falda acquifera del lago, della camera magmatica del Vulcano dei Colli Albani. Un’altra ipotesi corrente è che l’abbassamento del livello del lago sia dovuto esclusivamente all’abuso che ne fa l’uomo attingendo dalla falda attraverso pozzi.

WP_villaggio_macine

I resti del del Villaggio delle Macine lungo il lago Albano, agosto 2012 (foto Matteucci)

WP_villaggio_macine_detail

Dettaglio di uno dei pali (foto Matteucci)

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.

WP_acconcio_puglia_lesina

acconcio fishing system of Puglia

WP_lavoriere_Comacchio_Sargentini

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

WP_GE_Saline_Comacchio_2005

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.