Architectural Geology of Pennsylvania, Part 1: Cameron Mansion, Kings Gap Environmental Education Center, Carlisle (ca. 1908)
Looking northeastward at the center wing of the old Cameron mansion, now part of this facility''s complex of buildings.
This grand Italianate villa, perched atop South Mountain, looks like a worthy subject for my series on fieldstone structures. But the Center's own website description states that the bouldery, somewhat coursed, somewhat rubble-set rock exterior was quarried, not collected from loose surface rock.
And the source quarry was located on a "nearby ridge." In fact, the stone is the Antietam Quartzite, of Cambrian age. From the US Geological Survey description of the Antietam Formation, I gather it's a metaquartzite (originally sandstone that was subsequently metamorphosed) rather than an orthoquartzite (unaltered sandstone cemented with silica).
However, the metamorphism was not intense enough to obliterate the Antietam's characteristic trace fossils, marine-organism sediment boring tubes of the ichnogenus Skolithos. The rock is variously described as white, light gray, and weathering to a buff tone. The material on display seems to bear all that out.
If my Pennsylvania bedrock map is not deceiving me, the Antietam Formation outcrops in this neck of the woods on a ridge to the north of this site. It's not surprising that it forms a topographic high; quartzite is tough stuff and resists erosion better than many other types do.
In my travels in this state and Maryland, I have absolutely fallen in love with South Mountain, which despite its name is the northernmost portion of the scenic and historic Blue Ridge Province that stretches down all the way to Georgia. The effect South Mountain had on troop movements and dispositions during the American Civil War, especially in the battles of Antietam and Gettysburg, was significant, to say the least. And its geology is so thoroughly fascinating.
And here at Kings Gap, one of its most interesting rock units is on display in a striking and publicly accessible architectural setting.
Architectural Geology of Pennsylvania, Part 1: Cameron Mansion, Kings Gap Environmental Education Center, Carlisle (ca. 1908)
Looking northeastward at the center wing of the old Cameron mansion, now part of this facility''s complex of buildings.
This grand Italianate villa, perched atop South Mountain, looks like a worthy subject for my series on fieldstone structures. But the Center's own website description states that the bouldery, somewhat coursed, somewhat rubble-set rock exterior was quarried, not collected from loose surface rock.
And the source quarry was located on a "nearby ridge." In fact, the stone is the Antietam Quartzite, of Cambrian age. From the US Geological Survey description of the Antietam Formation, I gather it's a metaquartzite (originally sandstone that was subsequently metamorphosed) rather than an orthoquartzite (unaltered sandstone cemented with silica).
However, the metamorphism was not intense enough to obliterate the Antietam's characteristic trace fossils, marine-organism sediment boring tubes of the ichnogenus Skolithos. The rock is variously described as white, light gray, and weathering to a buff tone. The material on display seems to bear all that out.
If my Pennsylvania bedrock map is not deceiving me, the Antietam Formation outcrops in this neck of the woods on a ridge to the north of this site. It's not surprising that it forms a topographic high; quartzite is tough stuff and resists erosion better than many other types do.
In my travels in this state and Maryland, I have absolutely fallen in love with South Mountain, which despite its name is the northernmost portion of the scenic and historic Blue Ridge Province that stretches down all the way to Georgia. The effect South Mountain had on troop movements and dispositions during the American Civil War, especially in the battles of Antietam and Gettysburg, was significant, to say the least. And its geology is so thoroughly fascinating.
And here at Kings Gap, one of its most interesting rock units is on display in a striking and publicly accessible architectural setting.