REPORT ON THE ROMACONS FIELDWORK IN CHERSONISSOS,

10-12 SEPTEMBER 2007

 

John Peter Oleson (University of Victoria, Canada)

 

On 21 September 2006 the Ministry of CultureÕs General Department of Antiquities and Cultural Heritage, Department of Conservation of Ancient and Modern Monuments issued me a permit for the sampling of ancient concrete from harbour installations at Anthedon (Chalkida Province), Mavra Litharia (Korinthia Province), and Chersonissos (Limenas Chersonissou, Heraklio Province). The permit is granted for September and October 2007. The Ephorate of Underwater Antiquities Protocol number is 3-8-1006; the Department of Conservation of Ancient and Modern Monuments protocol number is 6-9-2006, and 81629. A copy of the permit is attached.

 

I planned to carry out this work in collaboration with Mr. Christopher Brandon (London) and Prof. Robert L. Hohlfelder (University of Colorado, Boulder), and with the assistance of Mr. Derek Klapecki, a graduate student at the University of Victoria. The projected schedule of our work was the following:

 

Chersonissos: 10-12 September 2007.

Anthedon: 14-17 September 2007.

Mavra Litharia: 18-20 September 2007.

 

Schedule of work, and procedures:

The team arrived in Chersonissos on 9 September. We identified ourselves to the Harbour Police, then with the kind assistance of Mr. Tolis Vougioukas, we arranged for the rental of a small boat and boat tender to carry our coring equipment (fig. 1). On Monday 9 September we visited the 23rd Ephorate of Prehistoric and Classical Antiquities in Heraklion, and with the diligent assistance of the Director, Ms. Maria Bredaki, we arranged for Ms. Eirini Karousou to observe our field work on 11 and 12 September. The weather and sea conditions were excellent, and two cores were recovered from the Roman period breakwater in the harbour basin (see Plan 1; fig. 2-3). After removal of the cores, the coring holes were filled with local sand to within 10 cm of the surface of each block. The remainder of each hole was then filled with a mortar composed of the same materials as the ancient block: lime and pozzolana. The cores are at present undergoing analysis at the Italcementi laboratory in Bergamo.

 

Description of the Cores:

CHR.2007.01.

Location: pila in water, second from the end of the mole on the east side of harbour, central northern portion. UTM 353943 E 3909741 N.

Water depth: 0.70 m.

Depth of core hole: 1.90 m, bottom not reached

Size of recovered core: 1.2 m, all fragmentary; nothing section longer than 0.12 m. (fig. 4)

Comments: The mortar was very crumbly, so only small portions survived the coring process; there was poor cohesion between the mortar and the aggregate. The longest intact mortar section was 0.10 m. The mortar seems very open and degraded. Possibly it was low in lime, either because of a poor mix, or from loss through chemical action or erosion. The mortar and aggregate both appear to be poorly sorted and poorly mixed, including fairly large chunks of tuff (up to D 0.028 m), large voids where a crumbly black mineral has fallen out (D 0.016 m, 0.014 m), and aggregations of lime nodules (D 0.002-0.004 m). The tuff is reddish yellow (7.5 YR 6/6); occasional inclusions of a more yellow, fibrous material, probably pumice (7.5 YR 7/8). Mortar from the upper portion of the core is a brown-grey colour, with coarse sand and lime nodules (D 0.005 m). Some mortar lumps near the base, at -0.70-0.80 m, are a very dark grey, with many small, well-mixed lime nodules (D 0.003-0.01 m). There appears to be a higher proportion of lime in this portion of the core (ca. 30%?), and less tuff. The aggregate (D 0.055-0.12 m) appears to be beach rock, with a yellow tinge (10YR 8/6). There are a few lumps of clay, one 0.04 x 0.08 m in size. Marine growth inside some core fragments suggests erosion of the mortar within pila.

 

CHR.2007.02

Location: quay wall near south shore of harbour, exposed above waterline. UTM 353835 E 3909705 N.

Depth of core hole: 1.52 m, bottom of wall was reached.

Size of recovered core: 1.49 m, in several sections; the longest section is 0.20 m. There was a small amount of grinding between 2 sections. (fig. 5)

Comments: Mortar seems very porous and granular, perhaps poor in lime. The lime nodules range in size from 0.004-0.025m, although mostly smaller. In addition to probably being short of lime, it is probable that this mortar was not compacted; it simply looks very loose. There are small pieces of tuff, ranging from 0.005-0.035 m, predominantly in the middle of this range. The kurkar aggregate is very irregular in size and shape, and irregular in distribution, from D 0.05 to D >0.18 m. It constitutes approximately 40% of the core. Sections 0 to -0.10, and -0.60 to -1.05 m are nearly free of aggregate. There were 2 atypical pieces of aggregate: 1 very hard, dark blue/grey stone, 0.06 x 0.09 m; 1 brown conglomerate 0.06 x 0.07 m. The bond between mortar and aggregate was very good; there was no fracturing of core at these joins, only within mortar sections

The mortar ranges from grey brown near 0.0 to yellow brown at -0.60, to grey at base, -1.40.

0 to -0.30. Kurkar aggregrate, very irregular. Mortar is pink (7.5YR 8/4), with many large, irregular chunks of a very fibrous reddish-yellow tuff or pumice (7.5YR 6/8)(D 0.004-0.020). Many lime nodules up to D 0.02. Occasional irregular small voids, but mostly a surface roughened by grinding and loss of soft surface material.

-0.30 to -0.60. Significant amount of subrounded black sand visible in mortar. Kurkar is very pale brown (10YR 8/3).

-1.38: a distinctive seam. Above is the usual poor mortar, then a seam, then below, to the bottom of the core a mass of crystalline black stone, probably held together with natural lime deposits, forming beachrock. There does not appear to be any tuff in this area, or mortar, only light grey, rounded pebbles, cemented by thin layers of a reddish yellow (7.5YR 8/6) material. Either the cement was laid on a natural beachrock formation, or a layer of pebbles was stabilized by the mortar and then was transformed into beachrock. Beneath this was a layer of soft, greenish grey clay.

 

Anthedon and Mavra Litharia

Unfortunately, during the work in Chersonissos, Oleson suffered a detached retina in his right eye and had to return to Canada for emergency surgery. The rest of the team travelled to Anthedon and Mavra Litharia, but after examining those sites they decided not to apply for permission to carry out coring under OlesonÕs permit. The materials found in the sea-level structures at those sites are unlikely to be concrete, but rather a naturally occurring beach rock.

 

 

Plan 1: Plan of Chersonissos harbour, with indication of 2007 core locations.


Figure 1: Boats with coring equipment.

Figure 2: Coring in progress at site of Core CHR.2007.01.

Figure 3: equipment in place for coring at site of Core CHR.2007.02.

Figure 4: Core CHR.2007.01.

Figure 5: Core CHR.2007.02.