Unfortunatly, alot of the damage to headstones are done by grave robbers.
There are alot of the older above ground headstones like this one, that have been shattered, broken down, and or completely removed so people can get inside.
These types of graves appear to be pretty popular.
They are thin above ground boxes that cover the grave site itself. But they appear to house very shallow graves.
This one, if you look closely, you can see the actual wood of the coffin not but 5 or so inches below the dirt.
Of course, most of it has been pulled up, but you can definatly tell it was very shallow.