An array of greys – blue, tan, dark, light, flecked, fossilized….. purple even! These words describe the rich tapestry of color and texture you can find in the famous variety of building stone known as Pennsylvania Bluestone. It has become a well-known part of the American tapestry over the past 200 years, being utilized in many historic buildings and facades, landscapes and sculptures, from the Catskill Mountains of northern New England to the craftsman homes of the Northwest.
It is no surprise that this type of stone has become so renowned – Bluestone is sturdy, easily worked and plentiful, in addition to being highly attractive to the eye. Though it is a type of sandstone, formed by ancient river sediment, it is much stronger than many other non-metamorphic sandstones, yet not so strong that it cannot be easily worked with a chisel and hammer. And it’s horizontal layers allow for some fairly accurate splitting.
Geologic shifts that began over 300 million years ago formed this stone, which is composed of fine fragments of feldspar, silica sand, and clay. These minerals coalesced at the delta of a huge river that ran from the Acadian Mountains (“Ancestral Appalachians”) which covered the area where New York City now exists. The slow and steady flow of water created the rippling effect that can be seen on the surface of flagstones today, and layer by layer the bedrock was formed.
Fast forward to the late 1800′s, during America’s Industrial Revolution, and Bluestone is being quarried in large blocks to build great works of architecture, like the Starrucca Viaduct across the Susquehanna Valley in upstate Pennsylvania. Some other historical Bluestone structures include “The Castle” in Hawley, PA (known to be the largest building made of the material), and the Bridge of Sighs at Pittsburgh’s Allegheny Courthouse. Another important but little-known site is Opus 40, a very personal and stupendous work of art created by a genius who lived on his own bluetone quarry outside of Saugerties, NY.
Pennsylvania Bluestone continues to be probably the most well-known building stone in the country, being readily shipped to all parts of the US and produced by hundreds of quarries in upper tiers of Pennsylvania, New York and New Jersey. Next time you see some covering a wall or forming a beautiful patio, remember that you are looking at a part of your country’s history.
by Mark Shepherd www.ShepherdStoneworks.com
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