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30 January 2014

Antietam Formation breccia with Fe/Mn oxide cement: 2 GigaPans

One of the intriguing rocks you find in Virginia, at the interface between the Valley and Ridge province and the Blue Ridge province, is distinctive brecciated Antietam Formation. The Antietam (sometimes known as the “Erwin,” especially in Shenandoah National Park), is a quartz arenite (quartz sandstone) that has been variably fused to quartzite in some places (but not others). It’s been deformed, sometimes spectacularly so, as we see when the …


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