PERMISSION:
Permission for placement of this earthcache was given by Tim Taglauer, Shenandoah National Park, to Rainbowtree who originally established this earthcache.
THANK YOU:
Thank you to Rainbowtree for her generous "gifting" her original earthcache, NP SD 33.1 Hazel Mountain Overlook for me to adopt. Lesson materials will be made to enhance the foundation of this earthcache. This earthcache will be in memory of my geocaching daughter, Sarah (GC name: SPFF) , who as a child along with our other children, would play and climb on these very rocks at the Hazel Mountain Overlook. This overlook holds a very special spot in our hearts. I cannot thank Rainbowtree enough for letting us honor our Sarah.
NOTE:
Road and weather conditions may necessitate closure of Skyline Drive in the Shenandoah National Park. Please check the status of Skyline Drive before making your final travel plans. There is an entry fee for Skyline Drive.
EARTHCACHE REQUIREMENTS:
Each cacher must send in their own answers when logging this find. After you arrive at this creation of nature, enjoy this geological feature and what you will bring home with you through this experience. Review the materials below and answer by message/email the questions to the best of your ability. Please follow all logging requirements and do not post any answers in your log. Please practice Leave No Trace ethics to help protect this area for future generations.
GNEISSIC TEXTURE:
Since a gneiss is mainly defined by its texture, understanding what gneissic texture looks like is helpful. Gneissic texture is a type of metamorphic poliation described as parallel bands of alternating light and dark minerals and ill-developed schisocity. Mineral grains are usually coarse appearing. One frequently overlooked aspect of gneiss is crystal size. In order for a rock to be considered gneiss, you have to able to observe individual crystals . If you don't see crystals without the aid of a hand lens then you may be looking at phyllite, a precursor to schist in the metamorphic process. Similarly, metamorphic rock that has not yet developed distinct alternating bands can't be labeled as gneiss. If you do see individual mineral grains, you are probably seeing schist. The difference between schist and gneiss is hazy and it is common to see a rock that displays both textures.
To identify gneiss, observe for alternating bands or lenses of light and dark minerals, usually over 5mm thick. The rock's crystals should be large enough to be seen with the unaided eye. The bands may be wavy but run parallel to each other. Larger crystals of minerals like garnet or kyanite may be interspersed throughout the rock.
To be considered gneiss, a rock must meet these requirements:
1. Metamorphic - formed from physical and chemical changes as a result of heat and pressure
2. Coarse-grained - the grains of the rock's matrix are visible to the unaided eye
3. Gneissic Texture - parallel, alternating bands or lenses of dark and light minerals with weak or no schistocity
GARNETS:
Some specimens of gneiss contain minerals with distinctive characteristics of the metamorphic environment. These minerals may include biotite, condierite, sillimanite, kyanite, staurolite, andalusite and garnet. Gneiss is sometimes named for these minerals, which include "garnet gneiss" and "biotite gneiss". These rocks contain minute grains of dark red garnet ranging in size from 1-3mm in diameter. They are best observed and appreicated on the sides of the outcrop facing East, away from the parking lot. Grains align during metamorphism when the rocks were heated and squeezed resulting in the existing minerals to recrystalize. Garnet was also formed during this metamorphic event.
Images of garnets in various rocks
QUESTIONS TO ANSWER:
1. Describe gneissic texture in your own words.
2. Describe gneissic texture in this outcrop
3. Observing the east side of the outcrop, describe the location of garnets within the rock and if they are aligned with the rock-forming minerals.
4. Are the visible garnets scattered randomly throughout the rock formation and is there a greater concentration in one area of the rock as opposed to another part?
5. Post a photo at or near the coordinates (you do not have to be in the photo unless you want to). This is your log signature.
RESOURCES:
Graphics via Internet Public Domain since no contact info available (Ranbowtree)
Geology Along Skyline Drive, Robert L. Badger, 2012 edition
GINGIN'S MESSAGE:
H - High in the mountains, we hear your sweet songs
A - Always in flight, like a bird soaring high
Z - Zealous the sound of nature beckoning us to stay
E - Ever looking forward to a world filled with joy
L - Loving each embracing hug of those closest to us
M - Memories, old and new, made at this site, laughter and smiles
O - Observe the intricate work of nature as it captivates our imagination
U - Understanding that we all impact this land, these formations, the wilderness
N - Nuture the young lives and teach stewardship as a foundation for their values to grow
T - Teach through example that care fosters caring for our environment
A - All things wild, on the land, water and air should be appreciated for their part in nature
I - Inspire others through your words and your actions, as actions are often louder than words
N - Never forget those you hold dearest, be they next to you or flying with the angels.