The discovery of useful brine resources in the embayed coastal zone of Qingdao is an important achievement in research on potential underground brine resources stored in Quaternary littoral facies in the North China coast. The Holocene transgression in this area provided the ancient seawater sources for forming brine. In spite of the unfavorable geological conditions (narrow littoral plain

shallow and thin Quaternary sedimentary strata) Qingdao's embayed coast has deposition basins with bay-in-bay and weir dam ideal for gathering brine. The geologic structure of the littoral Quaternary deposition basin and hydrologic condition (deficient runoff) comprise favorable environment for the formation and abundance of underground brine. The embayed coast geomorphy controls the distribution of brine in patches that form small mineral zones in some parts. The brine aquifer sediment series formed under Quaternary littoral plain sedimentary and hydrogeologic environment are usually single phreatic ones. Part of the thick deposit areas consists of phreatic and poorly confined aquifers. Near the river mouth

there can sometimes be brine aquifers interbedded with saline water ones. The basement of the brine ore deposits is comprised of Mesozoic rock formations. Underground brine is scattered almost all over the littoral plain and only in the larger plain's area is the narrow saline water belt distributed beyond the brine zone. The structural features of the brine aquifer sediment series along the Jiaozhou Bay Coast are typical of those in the North China coast. We name it “Jiaozhou Bay Type”. Its features are different from those of other brine aquifer sediment series such as “Laizhou Bay Type” and “Bohai Bay Type” in the littoral plain of the Bohai Sea.