贝壳堤就是在海岸带由海洋各类贝壳和碎屑等堆成的堤岗状地形。天津市地处渤海之滨,何曾知道天津市在4000年前还在大海淹没之中呢?当我们走出闹市到郊外看到的一些垅岗和土丘,它却可以告诉你很多有关天津市海陆变迁的往事。一、贝壳堤的形状和规模: 贝壳堤在渤海湾两岸已发现四条。它们大体都是与现代海岸平行, Shell embankment is in the coastal zone by the sea all kinds of shells and debris stacked embankment-like terrain. Tianjin is located on the coast of the Bohai Sea, Ever wondered that Tianjin was still inundated by the sea 4000 years ago? When we walked out of downtown to see some of the hills and mounds, it can tell you a lot of land and sea in Tianjin Change of the past. First, the shape and size of the shell embankment: Shell embankment in the Bohai Bay has been found four. They are generally parallel with the modern coast,