George --

Natural resistance to decay, wear and insect damage made cypress the best available wood available for marking graves. However, actual markings on the plank varied according to the time, resources and skills of the individual placing each slat. Markings were vulnerable to wear and fading, and if the inscription became illegible, the grave became that of an 'unknown'.

Also, however durable plank markers might be, storms and high winds might topple them over the years. Disrespectful or careless persons displaced others, poor people sometimes collecting slats for firewood. All too often, property owners simply desired to convert the land to other use. Many factors -- natural and human -- were at work against these frail markers.