The harbour of the mansio ad Speluncas (Brindisi, Italy): a key to the lecture of sea level changes in the past 2500 years?

The archaeological site Torre Santa Sabina is placed North to Brindisi along the Adriatic coast of Apulia, no far from the ancient Karbinia (the modern Carovigno). It is well known because of the continuous human presence from the Neolithic to the Middle Age, through the Mycenaean and Roman time. In particular it was named "ad speluncas" during the Roman Empire; at this time little villages named "mansiones" were placed along the main ways playing an important role as logistic stations between the main cities. Numerous archaeological structures and remains have been found below present sea level in the area of the ancient mansio ad speluncas. They permit to reconstruct the sea-level changes in the last 2500 years. Pile’s huts related to the XIV-XII century b.C. are placed along the water-front at about 1 m a.p.s.l.. A sewer channel of Roman age is preserved in the coastal area; it shows its outlet at 0.7 to 0.9 m below present sea level whereas medieval (?) quarries have their bottom up to 0.6 m below the present position. Unfortunately they are “land indicators” since they only indicate that sea level was lower the present position at the time of their building. In the area of the ancient harbour, the most important sea level indicators are two wrecks of Roman ships ascribed to the Late Republic or Ist century of Imperial Age. Beached at the mean depth of 2.5 m below present sea level, they could indicate the position of the sea level at the time of their abandonment on the beach. Messapic, roman and medioeval quarries are also present below present mean sea-level The archaeological remains suggest that about 3300 years ago the sea level stood up to 3 m below the present one; 2000 years it raised up to 2.5 m lower than the present one as also indicated by data coming from the near harbour of Egnatia. The following rise of the sea level has been responsible for the flooding of medieval structures