Special thanks to the National Park Service and Grand Canion National Park for allowing me to reproduce some of the content shown here.
This Earthcache is located in National Park Grand Canyon for which an admission fee is required. This Earthcache has no container. It only requires presence on coordinates.
Only 0.25 miles (400m) trip to EarthCache: allow 30 minutes. A short, but steep, walk ona trail to spectacular view of Grand Canyon. By the way, you'll take a little geology lesson. You will see fossils of marine origin. Is it possible? Answer to yourse! Yes, I invite you to the Bright Angel Point trail.
Chert - is a common compact, silica rock formed in limestone rocks. Is a hard, fine-grained structure composed of crystals of quartz (silica) that are very small. [Quartz (SiO2)]. Chert is often of biological origin (organic) but may also occur inorganically as a chemical precipitate or a diagenetic replacement. It is white or cream to dark brown in color. Depending on the chemical or organic composition, it may also be gray. It has a non-uniform structure. The boundaries are poorly marked in the ground. The border between the surrounding rock and the four is blurred, transient. Its cross-section is glassy. Gives the impression of being transparent. Cracks are often seen.
Flint-It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. Inside the nodule, flint is usually dark gray, black, green, white or brown in color, and often has a glassy or waxy appearance. A thin layer on the outside of the nodules is usually different in color, typically white and rough in texture. The border between the surrounding rock and flint is well marked. On the surface you can see a layer of white weathering. We call it bark. It is usually covered with light siliceous bark, softer than flint itself. Flint breaks and chips into sharp-edged pieces.
In the place designated by the coordinates we will see the Kaibab Formation rocks. It is a limestone sedimentary rock with an admixture of dolomite and sandstone about 350 feet thick, formed 270 million years ago during the Permian period. Limestone can be of organic origin (shells, hole saw shells) or inorganic (chemical origin) formed as a result of precipitation of calcium carbonate from sea water. Observing Kaibab limestone we will notice lumps of concretion. It is a hard, brittle rock made of silica that forms as lumps or "nodules" within limestone beds under the sea. The brown lumps are mostly made from the silica skeletons of ancient sponges called Actinocoelia. They are of organic origin with a high content of silicon.. Exactly: is it Chert or Flint.
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The photograph shows Flint from around Krakow, Poland.
To log this Earthcache, perform the following tasks and determine the answers to the questions below. Email me your answers, DO NOT include them with your Found It
We'd love it if you could also take a picture of yourself and post it with your find log.
1 / You can see the concretions against the backdrop of limestone. What is their color or structure?
2 / Specify! Are the boundaries between competitions and the surrounding rock clearly marked? or are they blurred?
3 / Is a white weathering layer (bark) visible on the edge of the concretion?
4 / If you answered questions 1-3, please write if it's Chert or Flint.
Remember, you are in the National Park. Follow the recommendations.
Used:David Bone – West Sussex Geology, Wikipedia, information from the Visitors center. Internet.
If you see language errors, write to me. I will correct the description to be more understandable.,br.