This section describes different excavation methods, both techniques used on land and in the water.

Marine archaeologist working inside the Mark I Enclosure System during the excavation of shipshed η/© ZHP 2002

Richard C. Anderson surveying the upper end of shipshed η in the basement of Sirangiou 1/© ZHP 2002

Sigrid Rasdal Eliassen and Ioannis Triantafillidis surveying shipsheds in the western part of Zea/© ZHP 2004

Mette K. Schaldemose registering finds inside a storage room kindly provided by Marina Zeas. Photographer: Bjørn Lovén/© ZHP 2003

A fold at the bottom, filled with sandbags, weighs down the curtain. Clear water is pumped into the enclosure system from further out in the harbour to create a working visibility. A dredge used for cleaning architectural structures underwater also removes dirty water and sediment from the enclosure. The system worked well during the 2002 campaign, but we intend to upgrade it using plastic tubing with a larger diameter, which will make the frame more buoyant. This improvement will also make it easier for the diver to be suspended during excavation work.

Electronic Surveying
Careful surveying holds an important key to the overall understanding of the surviving remains of ship-sheds at Zea. The reason is simple: very little of what survives is actually possible to see and these visible remains cannot visually be related to each other. Some lower parts of ship-sheds can barely be discerned through the shallow, murky water of the harbour while a few portions of the upper parts of the ship-sheds may be seen in the basement of Sirangiou 1.

Putting this physical evidence accurately together is essential to its understanding. To be able to put it together as a very tangible, 3D model is to suddenly develop “x-ray vision” that allows a viewer to clearly “see” the surviving elements, in their correct positions, from under the water, through the modern marina and road works, into the basement.

The surveying itself is not particularly challenging. The remains within the basement are a perfectly straightforward bit of “mining surveying” while the underwater work can be done as if it were on land because the target or prism of a normal detail pole always remains above the surface of the sea. Innovative methods have nevertheless been applied, especially in the form of a direct CAD (MicroStation) surveying system that has been developed by Nigel R. Fradgley of English Heritage.

Shooting has been done with a Leica TCR 300 series total station theodolite, recording its results directly in the form of a 3D MicroStation “wire frame” CAD model in the field. The CAD program runs on a Fujitsu Stylistic 3400 tablet computer with an indoor-outdoor screen so the work may be checked and edited as it is in progress. The Fradgley system offers a partial return to the sensitivity of “hand drawn” surveying while retaining the very high accuracy of modern electronic surveying.

The Leica instrument is very fast, fast enough to permit a point density sufficient to create attractive, block-by-block drawings, at the data-capture stage. This is particularly true of the above-ground work where most of the points are shot in the Reflectorless Laser mode, directly to the stonework. The underwater work is slowed down and made less accurate by the traditional “wobbly pole” effect of any electronic surveying that employs a hand-held, thus wobbly, “detail” pole. It is hoped that an easier (for the diver) floating and vertically self-stabilizing target pole can be devised that will allow the diver to concentrate entirely upon accurately locating the lower end of the pole on the surviving underwater remains.

Richard C. Anderson. Architect to the Agora Excavations, Athens

Finds Registration
The finds registration constitutes the basis for all subsequent studies of the finds and preparation for the final publication. At the Zea Harbour Project finds registration starts on site. During underwater excavation the diver collects all finds from each excavated context in a plastic crate. The person in charge of registration receives the crate at the harbour front, where the finds are transferred to plastic containers filled with salt water while modern rubbish, such as plastic bottles, beer cans, car tyres etc., previously were thrown out. From autumn 2004, however, all rubbish will be kept for environmental research.

Finds from underwater contexts are waterlogged and must be kept wet in order to prevent deterioration. Organic material, such as wood or leather would shrink and warp and at worst disintegrate upon uncontrolled dehydration. Inorganic finds, such as ceramics, are less vulnerable, but if they come from saltwater contexts they contain salts, which upon dehydration will crystallize inside the fabric and cause structural damage. All finds are therefore kept wet until they are moved to the conservation lab of the Ephorate of Underwater Antiquities, where all finds are conserved and stored. Finds from each context are kept in separate zip-lock plastic bags together with labels defining finds bag number, date of excavation and context. The finds are then sorted into the different groups of material: pottery, porcelain, tile, other terracotta (such as loom-weights), glass, stone, coins, iron, copper alloy, etc. The pottery is further divided into one of four subcategories determined by the composition of the clay-fabric: fine ware, medium ware, cooking ware and coarse ware. The finds database as well as the forthcoming preliminary publications of the finds will be available on this website.