Cartography and the identification of the blocks

Isabelle Hairy
May 2006

How can one envision the underwater site spatially so that one can then ask questions of it?

First of all, we mapped the site, plotting every ancient element by means of various techniques from the most traditional (triangulation and gridding) to the most modern (see: “direct topography” and “aquameter”). The measurements thus obtained are fed into a computer and lead to the creation of a map within a Geographic Information System (GIS) developed by MapInfo.

General plan of the sunken ancient blocks at the foot of Qaitbay Fort © CEAlex, map by I. Hairy, all rights reserved.

These virtual blocks are then, with the aid of Filemaker Pro, given an identity card that describes in both text and image (photographs and film) their extrinsic characteristics (depth, orientation and relative position) and their intrinsic characteristics (material, colour, dimensions, geometry, décor and function). As of 31 July 2005, 2,843 blocks had been entered into the database, which also holds information regarding the relief of the site and the objects of lead, iron and bronze discovered there. The gathering of data about space and material within the GIS allows us to create a virtual site, simplified perhaps but organised following certain pertinent information.
Thus removed from the constraints of the real context, the archaeologist or any other specialist can sit on dry land in front of a computer and explore the site once again and this time with a view to understanding what happened in the past.

Photos André Pelle, © CEAlex
all rights reserved

1 - Before proper observation of the blocks can be done the surface of the blocks is cleaned of any concretions and seaweed. This work must be repeated roughly every two weeks because of the high levels of pollution on the site.
2 - A diver with a board and block identity sheets.
3 - In the deepest parts of the site the blocks are piled up in several layers and so certain blocks must be lifted so that the archaeologists can study the lower layers. This is done with inflatable balloons in which the volume of air is calculated in relation to the weight to be lifted.

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