The building above is the Graham County Courthouse in Robbinsville in western North Carolina. The courthouse itself is built of hewn blocks, but the newer wall in front only consists of natural parted slabs. In the background of this image you can see the Blue Ridge mountains, part of the Appalachian chain of eastern North America.|
The Graham County Courthouse is built of quartzite, or metamorphosed sandstone, as shown below. This particular stone has not been intensely metamorphosed, and a metamorphic petrologist might view it more as a hard sandstone rather than as a metamorphic rock. However, original sand grains can't be seen in it, as the detailed image farther below shows, so that any original sedimentary texture has been obliterated by metamorphism.
The no-longer-sedimentary but not-very-metamorphic nature of this stone is typical of much of the rock in the Blue Ridge. By comparison, rocks in the Piedmont (to the southeast) have been intensely metamorphosed, and rocks in the Valley & Ridge (to the northwest) haven't been metamorphosed at all. In the Blue Ridge, partial metamorphism has added mystery and uncertainty to the stories recorded in the rocks, making the geologic history here even more intriguing, and controversial, than usual.
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