Crystal Creek Falls is a great location for lunch. There is a parking lot that will take you to a trail. From there you can walk in to the location. Keep a look out along the way to answer the questions. Half mile walk round trip, paved level walking trail. There is a water fall at the end but it is steep to go down. You can still view the falls from the paved trail. Enjoy! ~~~~~~~~~~~~~~~~~~
Granite
By definition, granite is an igneous rock with at least 20% quartz by volume. Granitoid is a general, descriptive field term for light-colored, coarse-grained igneous rocks. The word granite comes from the Latin granum, a grain, in reference to the coarse-grained structure of such a crystalline rock. Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite is usually found in the continental plates of the Earth's crust. It has a medium to coarse texture, occasionally with some individual crystals larger than the groundmass forming a rock known as porphyry. Granites can vary in color from pink to dark gray or even black, depending on their chemistry and mineralogy.
Most of the granites are associated with the Hercynian Orogeny that took place from about 380–250 M.A. and is the result of the collision between Laurasia and Gondwana that subsequently led to the formation of the supercontinent Pangea. Because of the widespread distribution of granites it is inevitable that they get used for a variety of purposes.
The Four Main Minerals:
Quartz:
quartz is a common mineral that is found in many different types of rocks. The chemical formula is Silicon oxide (SiO2). Impurities in the rock at the time of formation causes the quartz crystal to produce different colors. Quartz can be colored yellow, milky white, rose, brown to black, blue and the best known color purple amethyst.
Feldspar:
Feldspar is the most abundant mineral in rocks that are located at or near the earth's surface. Feldspar can have a glassy white, blue, green, pink or red crystals. When feldspars are exposed to the atmosphere they weather easily. Clays are formed by weathered feldspar. Kaolinite is the highest quality of the feldspar clays used by potters.
Hornblende:
Hornblende is a mineral that contains magnesium, iron, silica and aluminum. Hornblende is black, brown and green in color. It occurs in crystals of many igneous rocks.
Mica:
Mica can be clear, black, green, red, yellow, brown, purple lapidolite and other colors too. Clear mica was named Muscovite because it was found near Moscow, Russia. It was used as window glass in the Muscovite's homes. Muscovite contains water which helps to make it clear. Biotite mica is dark green to black in color because it contains metals such as iron and magnesium.
Origin of Granite
Granite is an igneous rock and is formed from solidifying magma. Granitic magma has many potential origins but it must intrude other rocks. Most granite intrusions are emplaced at depth within the crust, usually greater than 1.5 km and up to 50 km depth within thick continental crust. Granite is fairly common throughout the world. The origin of granite is contentious and has led to varied schemes of classification.
Mineralogy
Granite is listed as QAPF - Quartz-Alkali Feldspar-Plagioclase-Feldspathoid. Granites are named according to the percentage of quartz, alkali feldspar and plagioclase feldspar. Granite-like rocks which are silica-under saturated may have a feldspathoid such as nepheline. True granite according to modern petrologic convention contains both plagioclase and alkali feldspars. When a granitoid is devoid or nearly devoid of plagioclase the rock is referred to as alkali granite. When a granite contains grater than 10% orthoclase it is called tonalite. Pyroxene and amphibole are common in tonalite. A granite containing both muscovite and biotite micas is called a two-mica granite. Two-mica granites are typically high in potassium and low in plagioclase. Also the volcanic equivalent of plutonic granite is rhyolite.
Email Me The Answers To These Questions Before You Log Your Find. If you do not email me the answers your log Will Be Deleted.
1) What texture are the large rocks around the parking area?
A) Pegmatitic - A pegmatitic texture is one in which the mineral grains are exceptionally large.
B) Phaneritic - A rock with phaneritic texture has crystal grains large enough to be distinguished with the eye.
C) Vesicular Vesicles are holes, pores, or cavities within igneous rocks.
D) Aphanitic - Aphanitic texture consists of extremely small crystals.
2) What are the 3 words on the picture of the rubbing plate? *The rubbing plate is located up top near the falls by the railing and is handicap accessible.
3) What color are the granite rocks in the parking area.
4) Based on the descriptions above. How many kinds of granite do you see along the trail?
5) Name at least Two minerals from above that you think are in the granite.
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*Please Do Not Post Your Answers*
~ PARKING: There are fees for the NRA. The fees change so please check the site before you go.
You Can Check Whiskeytown NRA Fees Here.
The following passes are accepted in lieu of a Whiskeytown pass: Lassen Volcanic Annual Pass, Golden Age and Access Passports, America the Beautiful Annual, Senior and Access Passes.
Pass must be displayed on dashboard of vehicle.
~ Text & Image were adapted from this source.