Ingress Audio Engineering

Bluestone is quarried in western New Jersey, Pennsylvania and eastern New York.[15] It is also quarried in the Canadian Appalachians near Deer Lake in Western Newfoundland.[16]The Pennsylvania Bluestone Association has 105 members, the vast majority of them quarriers.[17] Bluestone from Pennsylvania and New York is sandstone defined as feldspathicgreywacke. The sand-sized grains from which bluestone is constituted were deposited in the Catskill Delta during the Middle to Upper Devonian Period of the Paleozoic Era, approximately 370 to 345 million years ago. The Catskill Delta was created from runoff from the Acadian Mountains ("Ancestral Appalachians").[18] This delta ran in a narrow band from southwest to northeast and today provides the bluestone quarried from the Catskill Mountains and Northeast Pennsylvania. The term "bluestone" is derived from a deep-blue-colored sandstone first found in Ulster County, New York.[citation needed] It can, however, appear in many other hues, mostly shades of grays and browns. Bluestone quarrying is of particular value to the economy of Susquehanna County, Pennsylvania. The Starrucca Viaduct, finished in 1848, is an example of Pennsylvania bluestone as a building material.[17]

The other, lesser known, type of American 'bluestone' is a blue-tinted limestone abundant in the Shenandoah Valley of Virginia. It is a limestone formed during the Ordovician Period approximately 450 to 500 million years ago, at the bottom of a relatively shallow ocean that covered what is today Rockingham County, Virginia. The limestone that accumulated there was darker in color than most other limestone deposits because it was in deeper waters exposed to less light. The darker blue color resulted in limestone from this region being dubbed bluestone and with two sequences measuring about 10,000 ft thick, it gives the area one of the largest limestone deposits in the world.[19] The stone eventually fades from a deep blue to a light grey after prolonged exposure to sun and rain. Given the abundance of the stone in the Rockingham County area, the first settlers used it as foundations and chimneys for their houses. When James Madison University was built, the local bluestone was used to construct the buildings because of its high quality and cultural heritage.[20]