沖ちゅう積せき層そう

noun

alluvium; alluvial stratum

Technical term in geology and geography for sediment deposited by rivers or floods.

• この地ち域いきの沖ちゅう積せき層そうは主おもに砂すなと粘ねん土どからなる。

  The alluvial stratum in this area consists mainly of sand and clay.