PARK RULES: Hours are from dusk to dawn. There is a $12.00 entrance fee, unless you have a Poppy Pass. DO NOT ATTEMPT THIS CACHE AFTER SUNSET.
*HOW DID ALL OF THIS GET HERE???*
During the Jurassic period, from about 160 to 140 million years ago, several volcanic island arcs were accreted as the ocean plate in which they were embedded was subducted beneath western North America. These rocks are interpreted to have originated as crystalline and volcanic oceanic crust, and deep ocean sediments. As they were attached to the continent, they were folded and metamorphosed. Near the end of the Jurassic or early in the Cretaceous, the subduction zone shifted west of the modern Great Valley. The magma generated by the subducting oceanic slab came up as isolated plutons in the western Sierra rather than coming up as part of the main Sierran Batholith. In the early Cretaceous, the Penryn and then the Rocklin plutons were emplaced within the western metamorphic belt. A long period of erosion wore away the volcanic peaks and metamorphic cover of the ancient Sierra Nevada, eventually exposing the granitic core beneath.
*SOIL*
Soils in the higher elevations of the lake are mostly thin, with numerous outcroppings of igneous and metamorphic rock. The bedrock strongly controls the type of soil. For example, loose soils of decomposed granite are common on the north and west side of Folsom Lake, while clayey, denser soils are common on the south side of the Lake.
Soil color is primarily influenced by soil mineralogy. Many soil colors are due to various iron minerals. The development and distribution of color in a soil profile result from chemical and biological weathering. As the primary minerals in soil parent material weather, the elements combine into new and colorful compounds. Iron forms secondary minerals of a yellow or red color, organic matter decomposes into black and brown compounds, and manganese, sulfur and nitrogen can form black mineral deposits.
Magnetite is a mineral and one of the main iron ores. With the chemical formula Fe3O4, it is one of the oxides of iron. Magnetite is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. Small grains of magnetite occur in almost all igneous and metamorphic rocks. Magnetite is black or brownish-black with a metallic luster.
Quartz is a defining constituent of granite and other felsic igneous rocks. It is very common in sedimentary rocks such as sandstone and shale. It is a common constituent of schist, gneiss, quartzite and other metamorphic rocks. Quartz has the lowest potential for weathering in the Goldich dissolution series and consequently it is very common as a residual mineral in stream sediments and residual soils. While the majority of quartz crystallizes from molten magma, much quartz also chemically precipitates from hot hydrothermal veins as gangue, sometimes with ore minerals like gold, silver and copper. Large crystals of quartz are found in magmatic pegmatites.
LOGGING REQUIREMENTS!!!
Please email/message me with the following information: GC75CF3 Folsom Lake Gets A Little Sandy | The Cacher names that are in your group (If in a group), along with the answers to the following questions:
1. At Stage 1: A) Did anything attach to your magnet? If so, what color were the grains? What does this mean is present? B) After examining the sand sample, what color are the sand grains made up of? Does the sample dissolve in the water when swished around? What size are the grains of each color type?
2. At Stage 2: A) Did anything attach to your magnet? If so, what color were the grains? What does this mean is present? Is there more or less than at Stage 1? B) After examining the sand sample, what color are the sand grains made up of? Does the sample dissolve in the water when swished around? What size are the grains of each color type?
3. At Stage 3: A) Did anything attach to your magnet? If so, what color were the grains? What does this mean is present? Is there more or less than at Stages 1 and 2? B) After examining the sand sample, what color are the sand grains made up of? Does the sample dissolve in the water when swished around?What size are the grains of each color type?
4. OPTIONAL: Post a photo of yourself at the posted coordinates.
FYI- I will only respond to your emailed answers if they are incorrect or incomplete.
**Sources:**
http://www.parks.ca.gov/pages/500/files/Geology.pdf
http://www.parks.ca.gov/pages/500/files/Soils.pdf
https://en.wikipedia.org/wiki/Soil
https://en.wikipedia.org/wiki/Magnetite
https://en.wikipedia.org/wiki/Quartz
CONGRATS TO GOLDENSTATEBOY AND ecrane FOR THE FTF!!!
SPECIAL THANKS TO RAPALADUDE, WILD DRUMM AND LOSTSAILRS FOR THEIR PRE-PUBLISHED REVIEW OF THE CACHE PAGE!!!