What is shown is evidence of the most common cause of failure of attempts at making long, clovis-morphology points: "End Shock".
Knappable materials are lousy at flexing; rather than bend, they will SNAP! When the end being fluted was driven downward by the impaact of the soft hammer (antler butt), the center flexed upward. Because the center was inadequately restrained by wrapped leather and hand pressure, the stone exceeded its elastic limit and fractured in tension.
Modern lithicists call the failure mode, "end shock". No doubt, prehistoric flintknappers -- who needed the point for survival -- had much more colorful expressions for the event!! '-)
TXnMA
