newcomers emigrating from more distant regions. Over time, the foreign elements tended to predominate over indigenous ones. About 3100 BC, et-Tell entered the "Urban A" phase. A large, well-planned walled city, about 110,000 square metres (~11 ha) in area, was built on the site. Some notable buildings from this time include a great acropolis complex consisting of a temple-palace compound, a market and residential area, and four fortified city gates. Sometime between 2950 and 2860 BC, the Urban A city was brought to an end by violent destruction. Most of the main buildings were burned to the ground; a layer of scorched stones and ash covers the floors of the EBI buildings. Early Bronze II Following this destruction, the city was rebuilt and entered into the "Urban B" phase, which coincides with the Early Bronze II period. Buildings were repaired and modified, and the fortifications were strengthened. Two distinctive new pottery shapes that first appear in this period suggest that new leadership was imposed on the city; these newcomers may also have been responsible for the destruction of the Urban A/EBI settlement. The Urban B city, like its forerunner, was destroyed violently by fire. Excavations uncovered the ruins of buildings, collapsed stones and beams at every site investigated. Fire trapped under the debris of collapsed roofs smoldered hotly enough to change the chemical composition of the stone, a process called calcination. The walls of the compound on the acropolis were tilted and displaced by a rift in the bedrock, suggesting that an earthquake may have been responsible for the destruction. This happened around 2720 BC , based on carbon-14 dating. Early Bronze III Following this destruction, the city lay in ruins for some time. Erosion channels cut through the debris; based on their depth and spread, the city was most likely abandoned for between 20 and 40 years. Finally, in the Early Bronze Age III, et-Tell was rebuilt and entered the "Urban C" phase. Egyptian influence in this stage is evident, attested by the use of stone pillars shaped with copper saws as well as other typically Egyptian building techniques. Two gates in the city wall, along with a great open reservoir designed to capture rainwater, are known. Around 2550 BC, there was a temporary disruption at the site, based on damage and rebuilding to the fortifications and major changes in the temple area. Finally, about 2400 BC, complete destruction