subjacent

adj

1. Lying beneath or at a lower level; underlying.

   “In some places, however, quartz reefs, payably auriferous while in Silurian rock, have been followed down to subjacent granite, and have there been found to thin out and become unprofitable […]”

   “Since the times of the Spanish conquest of the Americas, however, there had always been a subjacent stream of travel literature which had queried the civilizing function of Western penetration of such societies.”

   “[in relation to the second floor flat in a tenement building] the subjacent first floor and ground floor flats were ... owned by the first defenders.”