His silences had not proceeded from the unplumbed depths of his knowledge.
Down, down, to what unplumbed depths had it gone, those other times?
It cried to him out, as it seemed, of some unplumbed depth of experience in himself.
One drop of the salt estranging sea is as unplumbed as the whole ocean.
Helen grew conscious of unplumbed depths, of instincts at which she was amazed ...