METAMORPHIC ROCK:
Metamorphic rocks form under intense pressure and heat. Metamorphic rocks start out as igneous rocks, sedimentary rocks or other types of metamorphic rock. Through heat and/or pressure, the rocks change characteristics such as sheen, tightness of grain and hardness.
GNEISS:
Gneiss is a metamorphic rock formed by increasing heat and pressure. As this rock changed, embedded quartz minerals were also changed into various shapes (veins/pods/lenses) based on the pressure exerted. Gneiss is a common and widely distributed type of metamorphic rock. Gneiss is formed by high temperature and pressure causing a metamorphic process acting on formations composed of igneous or sedimentary rocks. Orthogeneiss is gneiss derived from igneous rock, such as granite. Paragneiss is gneiss derived from sedimentary rock, such as sandstone. Gneiss forms at higher temperatures and pressure than schist. Gneiss nearly always shows a banded texture with alternating lighter and darker colored bands and without a distinct foliation.
VEIN QUARTZ:
Quartz is often found in veins that cut through rocks. Although the term "vein" suggests this, the veins of quartz and other minerals are usually not thin tubes, but rather think sheets. The veins can form under various conditions and may or may not bear quartz crystals in them, depending on these conditions.
VARIATIONS:
-The gneiss here is folded and intruded by veins, lenses, and pods of quartz. Large deformed quartz veins are clearly visible at this outcrop.
-A bleb is a small bubble-like inclusion of one mineral within a larger rock/mineral.
-A lens is an inclusion that is thick in the middle and thin toward the edges.
-A pod is an inclusion that is long in one dimension and short in two dimensions with its long axis usually parallel to layering.
-A vein is a rock/mineral intruded into a fracture.
RESOURCES:
A Geologic Adventure Along The Blue Ridge Parkway in North Carolina by Carter/Merschat/Wilson ... 2001
QUESTIONS TO BE ANSWERED:
1. Observing the outcrop at this site, do you notice any quartz veins? If you do, describe it's direction of travel on the outcrop and it's approximate length.
2. Do you observe any pods within this outcrop? If so, how many to you notice?
3. Do you observe any lenses within this same outcrop? If so, how many do you notice?
4. Through your direct observations, what do you believe was the reason that this overlook was named Walnut Cove Overlook? What would the purpose of such an area served to those living in an earlier time?
5. Post a picture at or near the coordinates (you do not have to be in the picture unless you want to). This will be your log signature.
GINGIN'S MESSAGE:
W - Wanting to linger a little longer