ローム層[roomusou] stratum of loam
亜成層圏[aseisouken] substratosphere
一層[issou] much more
沖積層[chuusekisou] alluvium
下層[kasou] lower strata (classes)

下層階級[kasoukaikyuu] proletariat
下層社会[kasoushakai] the underworld
下層土[kasoudo] subsoil
化石層[kasekisou] fossil bed
階層[kaisou] class

ヨガの流行[yoganoryuukou] the cult of yoga
亜流[aryuu] bad second
暗流[anryuu] undercurrent
一次電流[ichijidenryuu] primary current
一流[ichiryuu] first-class

溢流[itsuryuu] overflow
渦流[karyuu] swirling current
押流す[oshinagasu] to wash away
横流し[yokonagashi] diversion into illegal channels
横流れ[yokonagare] flowing into the black market