The exact sequences at various locations have been studied extensively. Apparently the sea advanced and receded over the valley in conformance to an equilibrium between sedimentation and glacial advance or recession at 100,000-year intervals and 100 m (330 ft) to 120 m (390 ft) fluctuation of sea level. An advance began after the Last Glacial Maximum around 20,000 years ago, which brought the Adriatic to a high point at about 5500 years ago.[8]