For every headstone that is found and preserved, their are at least 10 that are destroyed, buried, or hidden. Developers with a Bobcat equipped with headlights hate headstones on land suitable for development, so they go out there at night and the headstones, or even entire cemeteries disappear.
Several of my ancestors had had the bad luck to suffer that fate, one within the last 30 or 40 years and several others over 150 years ago. This has been going on for many years.
Yup. A great many grave markers were handmade and in wood, and vanished. Many older stone markers were relatively soft, and I've watched the nearby markers of ancestors lose legibility just in my lifetime.