It is its own verification.
"The Expositor's Bible: The Gospel of St. John, Vol. I"
Marcus Dods
If I should depart from this rule in this instance, I would say that the similarity of the rocks on both sides of the great Columbia River gorge; the presence of submarine shells embedded in the great eastern basin, as well as the formation of its converging ridges, and the character of its soil, lend a certain tinge of verification to a portion of this legend.
"Memoirs of Orange Jacobs"
Orange Jacobs
The universe known thus we call "Nature," and the whole stock in trade of Science is the examination and verification of natural phenomena, with such inferences therefrom as ascertained facts legitimately suggest.
"The Old Riddle and the Newest Answer"
John Gerard