A friend, Brian Madden, recently brought me three flint nodules back from a holiday in Brighton. The nodules were fairly large and battered and I think possibly from the Birling Gap. The above is an early flake removal from one of the nodules and repeated points of impact on the surface are clearly visible. These marks are termed ‘Incipient Cones’, or the beginnings of cones of percussion. Karl Lee uses the term ‘ring crack’ for the halo like discolouration surrounding the points of impact. These incipient cones are presumably the result of impact with other flint cobbles on the beach.
This is a hard hammer handaxe rough-out made from a large cortical flake removed early on in the reduction (destruction!) process for one of these nodules. This view shows what was the original flakes dorsal surface, and my removals have revealed and isolated one of these cones of percussion.
I initially attempted to remove the cone but it became obvious that the impact that created the cone had effectively isolated it, and my removals simply revealed the already isolated cone. I am not sure whether to further thin this with an antler hammer and see what happens, or to keep it as an example of what a cone of percussion is.