Jim Gibb wrote: "While New Yorkers never appear to have selected chert of
the Onondaga or Normanskill varieties for architecture, roadbuilders use
the cherty limestone (17% chert as I recall) for crushed rock road paving."
 
        The use of cherty limesone for road building is not necessarily by
selection of its cherty qualities.  It is more due to the fact that the
cherty limesone couldn't be used for much more than crusher run and was
turned into gravel.  Building stone, cement and fertilizer needs the
calcium carbonate and the chert is an impurity.  Thus, railroad ballast and
road gravel all across upstate New York has a large percentage of chert.
        The crushing process will often create concoidal fracture patterns, bulbs
and all, that often are mistaken as evidence of tool manufacture or
working.  Railroads balast, which tends to be comprised of larger chunks of
stone and chert, has been know throw off an unsuspecting archaeologist who
looked at only the stones with particular fractures and not the thousands
of other "cores."  The driveway of my childhood home was made up of 1a
grade gravel made of cherty limestone and my Dad complained that it sliced
his tires to ribbons!  It made for nasty skinned knees, too.
        Agricultural activities will also fracture chert so that it looks like
purposeful cultural modification, but the presence of one nice bilb on a
piece of field chert doesn't (or shouldn't) make the grade in chert country.
 
Dan W.