Photo of the Day: Looking Glass Rock, North Carolina

Today’s photo may be a familiar one for those who have traveled the Blue Ridge Parkway or visited the city of Asheville, North Carolina, as it features a prominent landmark in the western North Carolina region. Looking Glass Rock – the massive rock formation seen in the photo’s foreground – is the northern face of a larger ridgeline rising along the headwaters of the Davidson River just west of Asheville. The rock itself it a hugely popular hiking and rock climbing destination and received its name due to the way sunlight reflects off of the sheer rock face when water freezes on its surface. Looking Glass can easily be seen from overlooks along several miles of the Blue Ridge Parkway south of Asheville.

Looking Glass Rock is geologically important because it represents an unusual type of rock formation present across a small part of the southern Appalachians, called a pluton. Although the name sounds like something from a science fiction movie, a pluton is actually what remains of an ancient ‘bubble’ of molten magma that arose underground during one of the Appalachians’ several mountain-building events. As the magma cooled, it crystallized into granite, and the softer rock surrounding the granite was easily worn away by the eroding effects of wind and water. With enough time for erosion to act, this easily-erodable layer of rock wore away, leaving the intact magma bubble remaining as a massive, sheer mountain of granite. (Many other plutons exist in the general area of Looking Glass, most notably Georgia’s Stone Mountain, which actually exists just outside of the Appalachians but is a wonderful example of the same geological phenomenon.)

Plutons are especially important to the ecology of the southern Appalachians since they provide a rare, exposed cliff-face habitat embedded within the larger forest. Plutons across the southern mountains, for example, host a number of rare plant and lichen species adapted to cliff-face habitats, and several plutons (including Looking Glass) host nesting populations of Peregrine Falcons – the fastest member of the entire animal kingdom. The peregrine declined during and shortly after the 1970s due to widespread pesticide use but has recovered in recent decades thanks to intensive conservation efforts. Peregrines are attracted to plutons as nesting sites, since this species requires high, exposed cliffs for nesting and rearing young.