John Rock and Looking Glass Rock

Overlooking Looking Glass Rock from the rock face of nearby John Rock

I went on a hike with some friends to the summit of John Rock in the Pisgah National Forest yesterday afternoon.  There was a winter storm in North Carolina the previous day, but the temperature got up to 47 °F which was warm enough to make almost everything melt by the time we started hiking near 1:00 PM.  The nearby Davidson River was swollen with the new snowmelt.

Geologically speaking, Looking Glass Rock is a pluton.  A pluton is a big ball of granite which would have become a volcano if it had not cooled before reaching the surface.  Volcanoes occur when at convergent boundaries when crust subducts and melts underneath the surface.  This melting crust forms magma (the same thing as lava, but lava occurs above the surface whereas magma occurs underneath the surface) which is less dense than its surroundings and rises toward the surface.  What are now the North American and African Plates used to be much closer together and were actually at a convergent boundary.  This convergent boundary formed the Appalachian Mountains when the oceanic portion of the plate subducted.  This continental collision formed the Appalachian Mountains which still exist from Alabama northeast up to Maine in the eastern United States.  We were so excited to view Looking Glass Rock from John Rock because the name “Looking Glass” is comes from how ice appears similar to a mirror when the sun reflects on it.  The warmer temperatures and exposure to sunlight actually made Looking Glass Rock not reflective, but John Rock’s pluton was mostly shaded and still covered in a layer of ice.

I am the biggest fan of hiking and geology in my group of friends by far, so I chose the hiking location and plan for the day.  Basically, they told me they would be up for going wherever I wanted to go.  The Pisgah National Forest is one of my favorite places for hiking because it is such a large area which is well maintained and protected.  My interest in John Rock and Looking Glass Rock came because of a lesson in class we had about the history of the Appalachian Mountains.  I wanted to know if I could see any of these ancient volcanoes which occurred because of the convergent boundary which originally formed these mountains.  Looking Glass Rock and John Rock would have been volcanoes, but the magma in both of these areas cooled too quickly before forming into volcanoes.  The Appalachian Mountains were once connected to the African continent, but later broke apart and moved away based on the hypothesis of continental drift.  The dominant force in this area is erosion, but many think that the Appalachian Mountains were once as high as the Rockies.  Veins of quartz were seen in the granite as well as seen along the trail itself.

Many mountain peaks I have hiked to in North Carolina feature granite outcrops, so I find these areas to be particularly interesting and beautiful.  Beacon Heights and Rough Ridge are two favorites.

A view of the mountains taken from the rock face of John Rock

Mountain laurel and rhododendron were everywhere along the trail and even right beside the rock face

Want to go?  Want more information?
http://www.blueridgeheritage.com/attractions-destinations/looking-glass-rock

Enjoying Geology while Hiking

I like to head to the Blue Ridge Parkway roughly about once a month to do some serious hiking. My major deciding factor on which trail I want to hike is simple. I want to see views.

http://www.blueridgeparkway.org/v.php?pg=61 is a link from the Blue Ridge Parkway’s website of the hiking trails within North Carolina according to overlooks and mile markers. Most of the trails are listed, but somehow there are a few trails missing. Anyone who sees this list may wonder about the trail names and what they mean. I know I did. My goal with this first entry is to give a rough explanation, geologically speaking, about what some of the features in the trial names mean. Balds and knobs are just two examples of features I had never known about before I actually was first able to experience them and see them in real life. How would I describe these features to other people though? These definitions are how I would describe these features and are not completely accurate, so I hope that anyone who reads this can offer some more insight by leaving a comment. My assumption is that these features are probably found in mountain ranges of different areas, but maybe these particular terms are of some sort of southern Appalachian vernacular.

A bald is a summit or crest of a mountain which is covered by native grasses or lowlying shrubs rather than covered by a heavy forest. I was told by a hiker before that a bald occurs in the southern Appalachian Mountains because of the unique climate which has too short of a growing season for forests. So does this mean that a “bald” only occurs in this area? Maybe. This strange occurrence is unique because a bald occurs with a warm climate and high elevation, and these factors are often very suitable for forest growth.

A knob is a hill or mountain with a rounded top. A rock climbing buddy once told me that knobs are fun for bouldering. An important feature of a knob is that it does not have much or any plant cover.

A pinnacle occurs at the top of a mountain where there is a sharp peak. The first pinnacle I ever hiked to the top of was actually part of Crowders Mountain in Gaston County, North Carolina. It is about 45 minutes or an hour from where I live, so it is somewhere I enjoy hiking frequently.

A gap is an area along a mountain ridge which is lower than the surrounding areas. Windy Gap is an area which comes to mind whenever I think of a gap because it is an area I traveled to frequently as a child. Maybe its name is “windy” because this lowlying area acts sort of like a wind funnel?

I may not have defined these terms correctly or in a manner which is the least bit helpful, but the whole purpose of science is the pursuit of new knowledge. I will be the first one to ask questions because I know I do not have all the answers. Keep exploring.

And Wikipedia has a great list of balds at http://en.wikipedia.org/wiki/Appalachian_balds for anyone interested