UNDERWATER ARCHEOLOGY — BASS 463 



A preliminary survey revealed that the wreck rested on a rocky 

 bottom with almost no covering of sand to preserve wood and other 

 organic material. The metal cargo was still in situ, but it was cov- 

 ered with a lime sea deposit up to 8 inches thick, and hard as concrete. 

 The concretion presented a double problem : how to make an accurate 

 plan of the objects imbedded in it, and how to remove and preserve 

 fragile artifacts such as bronze knife blades and spearpoints without 

 breaking them. 



On land such problems could have been easily overcome, but on 

 land there is not the all-important time limitation. Underwater, a 

 diver must breathe air at the same pressure as the pressure of the 

 water surrounding him. The deeper he goes and the longer he remains 

 at any depth, the more pressurized nitrogen will be absorbed by his 

 body. If the diver ascends too rapidly, the nitrogen will come out of 

 solution with much the same effect as bubbles appearing in a bottle 

 of champagne when it is uncorked. Such bubbles in the body may 

 block the bloodstream in various areas, causing the crippling and 

 often fatal divers' disease known as the bends. The only precaution 

 is strict adherence to diving tables giving the rate of ascent following 

 dives of various depths and duration. At Gelidonya the practical 

 limit was only 1 hour and 8 minutes for each diver to work each day. 



In order to save these precious minutes on the bottom, it was decided 

 to cut loose lumps of concreted cargo, weighing up to 300 pounds a 

 piece, and to raise these intact. Before being cut free with hammer 

 and chisel, each lump was marked in several spots. These spots were 

 triangulated with horizontal metertapes running from fixed reference 

 points driven into the rock around the site. The triangulated points 

 were put onto a plan and the lumps were raised to the surface with 

 a winch and cable. In one instance wood was seen protruding from 

 beneath a heap of concreted cargo. Winching from a small boat in 

 a rough sea presented the real danger that this fragile evidence might 

 be crushed. The mass of concretion was, therefore, attached to a 

 large plastic balloon with a lifting force of 400 pounds ; the balloon 

 was inflated on the bottom from a diver's mouthpiece and carried the 

 cargo gently to the surface. 



The lumps of concretion were carried to the expedition camp and 

 reassembled exactly as they had appeared on the seabed. Then they 

 were cleaned with chisels so that the cargo finally lay free and could 

 be drawn and photographed in detail. Using the points triangulated 

 on the bottom, the architect was able to add the details to his overall 

 plan which now showed the position of each object as it had rested in 

 the ancient ship. A record of the work in progress was also kept in a 

 number of "aerial surveys." These were made by a photographer, 

 with plumb line and level attached to his camera, swimming at a 



