Southeast Arkansas Welcome Center Earthcache on Hwy 82
Arkansas is known as the Natural State. Arkansas has some of the nicest and prettiest Welcome Centers in the country and there is such a variety of geological features and terrain as your travel across the State of Arkansas. I always enjoy traveling Arkansas roads for this reason. At this Welcome Center Earthcache and other featured Arkansas Welcome Centers, I will feature the Granite slab that spells out the state name, Arkansas. The Granite stone used at each Arkansas Welcome Center was taken from mines near the State Capitol of Little Rock, AR.
This is an earthcache, which is a kind of virtual cache where there is no physical log for you to sign, but instead, there are some questions that you must answer while here and then you must send me the answers to those questions either by email (which I prefer) or by message using the smart phone geocaching app. I strongly suggest that you send me your answers BEFORE LOGGING a find. I hate to say this, but if you do not send me your answers within 5 days of your logging this cache find, I will have to delete your find / log.
If you enjoy this roadside Earthcache, please consider giving it a favorite point.
Questions
1. Look carefully at the granite. What colors are present? (3)
2. Using the information in the description below, what minerals are present?
3. What is the diameter of the largest of the mineral crystals in centimeters?
4. On a relative scale of FAIRLY SHALLOW, DEEP. Or VERY DEEP, how deep beneath the Earth’s surface do you think this rock was when it formed? (See Crystal Size in the description below)
5. Does this polished granite show any signs of weathering?
6. Take a picture of the granite while at the Arkansas Welcome Center. Optional – include yourself in the picture.
Granite
Granite is a light-colored igneous rock with grains large enough to be visible to the unaided eye. It forms from the crystallization of magma beneath the surface of the earth. It is composed mainly of quartz and feldspar with minor amounts of mica, amphiboles, and other minerals. The mineral composition gives granite its Red, Pink, Grey, or White color with dark mineral grains visible throughout the rock. Granite is probably the best known of igneous rocks.
Crystal Size:
The size of the mineral grains is determined by the time it took the granite crystals to form. The slower the cooling rate, the more time that the crystals had to grow. As a general rule, the closer the magma was to the Earth’s surface, the more quickly it cooled, the smaller the crystals in the granite and conversely, the deeper the magma was beneath the Earth’s surface, the slower the magma cooled, the larger the crystal grains. Granite with crystals greater than a centimeter in size are called Pegmatites. Pegmatites crystals would have cooled very slowly.
Uses of Granite:
Granite is a rock that is often quarried as a “Dimension Stone” (a natural rock material that has been cut into blocks and slabs of specific dimensions). Granite is hard enough to resist abrasion, strong enough to bear significant weight, inert enough to resist weathering, and accepts a brilliant polish. Rough cut granite is used in buildings, bridges, paving, and monuments. Polished Granite is used in counter tops, floors, steps, and many other decorative applications. Granite is also used widely as crushed stone and aggregate.
Famous Granite Outcrops:
Some famous granite outcrops include Half-Dome at Yosemite National Park, the four Presidents carved into Mount Rushmore, and the Stone Mountain batholite near Atlanta, GA.
Density of Granite:
The density of granite is approximately 2.7 g/cm3 or 168.6 lbs. / cubic foot
Colors in Granite:
Quartz is milky white
Feldspar is white and grey
Potassium Feldspar is pink
Biotite is black or brown
Amphibole is greenish
Documentation:
Wikipedia.con – Granite
Geology.com > rocks > granite
www.gmqrock.com – Granite Mountain Quarries