Natural sludge, peat or bog iron layers without any cultural relics between two cultural layers, found in archaeological
excavations in the Yangtze Delta area, show that there are many unidentified
cultural interruption phenomena in many Neolithic cultural sites. They mainly appeared in 3 periods: (1) late Songze Culture—early Liangzhu Culture (5?300～4?700?yr BP), (2) late Liangzhu Culture early Maqiao Culture (4?200～4?000?yr BP), and (3) late Maqiao Culture—early Shang Zhou Dynasties (3?300～3?000?yr BP). Moreover, there are many Holocene buried paleo trees and peat deposition discovered during Quaternary geological investigation and civil engineering construction in this region. They were mainly concentrated in 4 periods: (1) early stage of Atlantic Phase ( 7?000 ～6?000?yr BP), (2) late stage of Atlantic Phase (5?500～5?000?yr BP), (3) middle stage of Sub Boreal Phase (4?400～4?100?yr BP), and (4) late stage of Sub Boreal Phase (3?600～3?100?yr BP). All these phenomena could possibly be the reflection of middle low frequency fluctuations of climate and sea level. They could have derived mainly from large scale land floods caused by powerful activity of summer monsoon under high temperature and high sea level, having nothing to do with marine transgression.