Unfathomable in example sentence
It had been necessary in sinking the Voreux to establish two tubbings: that of the upper level, in the shifting sands and white clays bordering the chalky stratum, and fissured in every part, swollen with water like a sponge; then that of the lower level, immediately above the coal stratum, in a yellow sand as fine as flour, flowing with liquid fluidity; it was here that the Torrent was to be found, that subterranean sea so dreaded in the coal pits of the Nord, a sea with its storms and its shipwrecks, an unknown and unfathomable sea, rolling its dark floods more than three hundred metres beneath the daylight.