EARTHCACHE REQUIREMENTS
Each cacher must send his/her own answers BEFORE logging a find. Enjoy the journey (learning adventure) as well as the destination (smiley earned). Remember to take only pictures and leave only footprints. To get credit for this Earthcache, complete the following tasks:
1. MESSAGE …. a. How many concretions are visible from the posted coordinates? ... b. Where are they located (top/middle/bottom)? ... c. Estimate the average size of these concretions.
2. MESSAGE …. Where does the greatest concentration of yellow deposits appear?
3. LOG …. Post a picture at or near the coordinates. This picture is your log signature.
4. LOG …. The rock (waypoint) has been sculpted mainly by the action of water. a. Give one scientific explanation for its appearance. / b. Give one creative explanation for its appearance.
5. LOG …. Find another rock sculpture anywhere along the creek. a. Post a picture. / b. Give one scientific explanation for its appearance. / c. Give one creative explanation for its appearance.
OPTIONAL - Please respect the time and effort involved in creating this earthcache by adding A and B to your log.
A. JOURNEY OF THE MIND ... Science explains what we observe. Relate (in your own words) something you found interesting in the reading. This adds to your learning adventure and your log.
B. JOURNEY OF THE HEART ... Art shares our personal experience of what we see. Share something special you found on site, and why it is special to you. This is a memorable addition to your log and will make other hearts smile.
Journeys of Heart and Mind ...
Stories to Touch the Heart and Puzzles to Challenge the Mind / Rainbow Tree Story
Thank you clayshaper for your help developing this earthcache.
CONCRETIONS
Concretions are formed when minerals dissolved in water collect around a “seed” object such as a shell, bone, or even a small piece of rock. They form along with the host layer, or shortly after the layer forms, but before the total hardening of the shale, allowing the concretions to become imbedded. The mineral content of concretions is usually different (and harder) than the surrounding rock, allowing them to weather out.
A concretion is a volume of sedimentary rock in which a mineral cement fills the porosity (i.e. the spaces between the sediment grains). Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word 'concretion' is derived from the Latin con meaning 'together' and cresco meaning 'to grow'. Concretions form within layers of sedimentary strata that have already been deposited. They usually form early in the burial history of the sediment, before the rest of the sediment is hardened into rock. This concretionary cement often makes the concretion harder and more resistant to weathering than the host stratum.
Concretions are commonly composed of a carbonate mineral such as calcite. They are found in a variety of rocks, but are particularly common in shales, siltstones, and sandstones.
18 MILE CREEK BOULDERS
The boulders imbedded in the wall shale of eighteen mile creek are calcite concretions. The climate of what is now Western New York during the Middle Devonian was tropical. Glaciation of the area did not occur until a much later period. Thus, the boulders that appear to have been dropped in strata where they do not belong can not be glacial deposits.
18 MILE CREEK DEPOSITS
There are yellow deposits on the walls of this site. Their appearance varies in intensity, so they might be bright or subtle on the day of observation. The yellow is produced when water charged with sulpheretted hydrogen from oxidized pyrite trickles out and is chemically decomposed on the surface, leaving sulpher deposits.
RESOURCES
http://www.dnr.state.oh.us/Portals/10/pdf/GeoFacts/geof04.pdf
http://en.wikipedia.org/wiki/Concretion
http://www.kgs.ku.edu/Extension/KGSrocks/concretion_def.html
18 Mile Creek Deposits …. This chemical process is described in detail by S.H. Emmens (1892) as cited by Amadeus W. Grabau: Geology and Palaeontology of Eighteen Mile Creek. Facsimile edition published by the Hamburg Natural History Society, Inc. (1994). Originally published in two volumes by the Buffalo Society of Natural Sciences. (1898-1899).
A cross-section showing the Devonian strata of an eighteen mile creek wall. This illustrates how the boulders are imbedded.
http://www.geology.buffalo.edu/contrib./people/faculty/gly216trip.htm
Photographs of a similar Western New York formation. (Scroll down)
http://www.fredonia.edu/department/geoscience/Lash/fractures/joints.htm