Hammer stone used with chisel
stonein experiments showing
side. (Keyser , James
I do feel compelled to note, however, that this paper and communication are both about an experiment, and that he has not yet reported finding such chisel stones. Admittedly, there has probably been little awareness of their possibility so no one has looked for them. Also, Keyser also commented that as they are smaller and lighter than the hammer stones they may have regularly been carried away as useful tools, not dropped in the ground when the petroglyph is done as so many hammer stones were, " that’s the beauty of a chisel stone—you can carry two or three dozen of them with the same weight as a single good-sized hammer stone." (Keyser 2016)
And I also must confess that I have never examined the fine lines in a petroglyph for this phenomena, superimposition yes, mis-strikes no. So in the future I will have another line of evidence to look into.
Those who would like to dig a little deeper into this example are referred to the 1999 paper by Keyser and Rabiega, cited below.