Pennsylvania Blue Marble

Posted on June 1, 2014 Updated on September 20, 2015

Bizarre marine arthropods of the Cambrian Explosion roamed a vast sea which covered what is now Valley Forge National Park.  Relax, we refer to events of 450 million years ago.  Under this sea there formed a weakly metamorphosed calcite marble.  Fast forward, to the early days of The Republic.  This Pennsylvania Blue Marble became an  important regional building stone in the first half of the nineteenth century.

One has but to tour older Philadelphia row home neighborhoods to see its extensive use as steps,  window sills, lentils, and trim.  Alas, structural decomposition, changing design tastes, and improved transportation systems increased  availability of better quality white marbles from New England and Georgia.   What becomes of the Pennsylvania marble as buildings are pulled down?

People like me collected steps and sills in nicer condition for garden use.  Wear patterns tell the story of healthy, prosperous neighborhoods.  Tool marks upon the ends aid one in establishing production date, as methods of stone dressing evolved.  The 350 pound steps were welcomed by friends and neighbors, as well.  A unique pillar for the garden bird bath or flower-pot.  And the sills make great bordering stones!  Pictured is a local effort.  These stones were pulled from houses under demolition within Philadelphia’s Fairmount section.