This monument was put up in 1878, but it remembers the whole Johnston clan, going back to the nearly indestructible Jane Johnston, who was born in 1700 (or possibly 1699) and died in 1806 at the age of 106. During that time she surely had many interesting adventures, including crossing the Alleghenies to settle in the frontier of Western Pennsylvania when she must have been already an old woman.
We should note, by the way, that when a cemetery inscription says “in the 106th year of her age,” it almost always means “at the age of 106,” not (as it should) “at the age of 105.”