It's sedimentary:
Sedimentary rocks* are types of rock that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle in place. The particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, the sediment was formed by weathering and erosion from the source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers, which are called agents of denundation. Sedimentation may also occur as minerals precipitate from water solution or shells of aquatic creatures settle out of suspension.
The sedimentary rock cover of the continents of the Earth's crust is extensive (73% of the Earth's current land surface), but the total contribution of sedimentary rocks is estimated to be only 8% of the total volume of the crust. Sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding. The study of sedimentary rocks and rock strata provides information about the subsurface that is useful for civil engineering, for example in the construction of roads, houses, tunnels, canals or other structures. Sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores.
Clasification of sedimentary rocks based on origin:
Sedimentary rocks can be subdivided into four groups based on the processes responsible for their formation: clastic sedimentary rocks, biochemical (biogenic) sedimentary rocks, chemical sedimentary rocks, and a fourth category for "other" sedimentary rocks formed by impacts, volcanism, and other minor processes. Each classification is also subdivided.
- Clastic sedimantary rocks are composed of other rock fragments that were cemented by silicate minerals. Clastic rocks are composed largely of quartz, feldspar, rock (lithic) fragments, clay minerals, and mica; any type of mineral may be present, but they in general represent the minerals that exist locally.
- Biochemical sedimentary rocks are created when organisms use materials dissolved in air or water to build their tissue.
- Chemical sedimentary rock forms when mineral constituents in solution become supersaturated and inorganically precipitate. Common chemical sedimentary rocks include oolitic limestone and rocks composed of evaporite minerals, such as halite (rock salt), sylvite, barite and gypsum.
- "Other" sedimentary rocks includes rocks formed by pyroclastic flows, impact breccias, volcanic breccias, and other relatively uncommon processes.
How to Log This Earthcache
Send me your answers BEFORE logging the find.
You must visit the area in order to get credit for this Earthcache. Armchair finds will be deleted without explanation (see Earthcache Guidelines). In order to claim the find, send me an email using the link just below the Earthcache title with the answers to the following questions:
1) The processes that make up this boulder are completely natural. However, it is highly unlikely that this boulder formed here. How do you think this boulder got here?
2) What material most likely makes up this boulder? How would you classify this boulder using the classification system above?
3) Is the surface of the boulder smooth or rough? Do you see any crystals present?
4) In what environment do you think this boulder was formed?
5) What does your GPS receiver say is the elevation at your present location? If you do not have a GPS with you, use your phone. many phones and several geocaching apps can tell you your present elevation.
6) (Optional) This is not required for logging this Earthcache, but it makes for a fun memory of your find. Post a picture of yourself or your entourage anywhere in the rest area.
Send me the answers to these questions along with the GC code and the number of people in your party (with their geo nicknames) BEFORE you claim the find. I reserve the right to delete your log if you log the find first even if your answers are correct when I get them. I'm pretty lenient with every other requirement except this one.
*Souce: Wikipedia
