層相 is read as そうそう (sousou) and means facies.
そうそう
sousou
そうぐん
(geol) group
そうか
sheafification
そういがく
stratigraphy
そうべつ
stratification
そうりゅう
laminar flow
そうじょう
stratified
そうかんり
layer-management
ぞうしょう
Minister of Finance
のうしょう
Minister of Agriculture
こうしょう
Welfare Minister
けっそう
expression
そうむしょう
Minister of Internal Affairs and Communications