Harbison Meta-Granodiorite EarthCache
Harbison Meta-Granodiorite
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This Earthcache is just off the Spider Woman II Trail in Harbison State Forest. This trail is popular with mountain bikers. There is a $5 ($25 annual) parking permit fee which can be paid at most of the marked parking areas. The gates are locked after 4:30 pm. Check the posted signs for seasonal variations to the gate schedule.
You will need to bring a measuring device to be able to complete this Earthcache.
In 1958, geologists from Duke University and the University of South Carolina identified an new type of Granite rock. It was classified as Harbison Meta-Granodiorite. Named so after the Harbison State Forest as this was the only place it was found.
Granite is an igneous rock that is composed primarily of four minerals. The term "Granite" is derived from the Latin word "Granum" meaning "grain" because of its granular nature. During Earth’s childhood, magma cooling very slowly far under the planet’s surface, allowed crystals of four minerals to grow large enough to be easily seen by the naked eye. These minerals are quartz, feldspar, mica, and usually hornblende. However granite is not a homogenous rock and it's composition varies depending on its location. Other less common components give granite a wide variation in look and color.
Granite is light in color because it is composed largely of minerals that are rich in silica. These include quartz, feldspar (orthoclase and plagioclase), and muscovite (a mica). Quartz is milky white, feldspars are pink, white, or gray, and muscovite is silvery. The dark color of granite comes from dark colored minerals, including hornblende, augite, and biotite (another mica). These minerals are green, brown, and black in color.
Granites actually come in many different colors. This variety in granites is caused by differences in mineral composition, especially in the feldspars. If feldspars are potassium-rich (orthoclase) the granites may be tan to reddish in color. If feldspars are calcium-rich (plagioclase) light to dark gray colored.
#1 - Based on the color is the feldspar calcium rich (plagioclase) or potassium rich (orthoclase)?
#2 - At the coordinates you will find a large, rounded boulder, it makes for a nice resting spot. Using a measuring device what is the circumference of this granite rock?
#3 - What is the elevation at the posted coordinates?
Additional Hints
(No hints available.)