ˈinˌlī(ə)r noun
Etymology: in (IV) + -lier (as in outlier )
1. : a mass of rock whose outcrop is wholly surrounded by rock of younger age
2. : a distinct area or formation that is completely surrounded by another
inliers of an older, wilder landscape surrounded by improvement — H.C.Darby
also : enclave
abolish the numerous outliers and inliers of territory — R.E.Dickinson