Subject: Can a man hammer with a 1 lb stone to exert a force of 20,000 psi?

The Cooperton site has mammoth bones that are suspected of human 
modification using hammerstones weighing 1 lb or less.  It has been said 
that it would take 20,000 psi to fracture these bones when they are green.
They are suspected to have been broken green due to the spiral fractures.  
I am unsure a man could exert such a force especially considering these men  
substantially smaller than human beings today.

Re: Can a man hammer with a 1 lb stone to exert a force of 20,000 psi?