California has some of the most interesting geology in the world, and some of it can be easily seen at Low Gap Regional Park. Much of the geology of California is a result of a process called subduction. Subduction occurs when two land masses (called tectonic plates) are pressed together and one is forced to submerge under the other; or, in the case of California, where the sea floor collides with the continent and is forced to go under the continent. At the contact point of the two land masses there is heat buildup from friction, pressure, and because sea floor is involved, plenty of water. The result of these conditions on the contacting rock is metamorphic in nature. The sea floor is made mostly of olivine. Some of this material undergoes a transformation as a result of subduction. The olivine becomes “serpentinized” as it reacts with water at elevated temperatures and is converted into a series of rocks and/or minerals called serpentinite, sometimes called serpentine. Serpentinite forms include soapstone and asbestos. Serpentinite comes in many colors from grey to green to dark brown. It often has a flaky or crumbly texture, and can have a soapy or shiny luster. Serpentinite soils are toxic to many plants, and so regions where serpentinite are common often have little vegetation. For further reading on this subject, see the references at the bottom of this cache description.
At ground zero of this cache, you will find a grassy slope with exposed rock. Once there, please answer the following questions and send the answers to me through my geocaching.com profile (Do NOT post the answers in your log!!):
1. Identify the rock, and then give the following supporting evidence:
a) What is the color of the rock?
b) What is the texture of the rock?
c) What is the luster of the rock?
d) How would you describe the surrounding vegetation?
2. What evidence is there for subduction at this site?
3. Give me the elevation of this particular outcropping, from top to bottom. (This is done by taking an elevation reading at the given co-ords, and then at the bench beyond and above the outcrop. Once you have taken elevation readings at both locations, take the difference and send me the number. That’s your answer. There is a trail from the old amphitheater that goes up to the bench, I highly recommend taking it.)
4. (Optional) Take a picture of yourself at the bench. (PLEASE don’t take a photo at the listed co-ords, that would give some of the answers away!) Groundspeak does not require geocachers to submit photos for earthcaches anymore, (and I cannot/will not delete your log just because you don’t post a photo) but it sure is helpful to have them. They help to prove that you were actually at this site. I’d love to see your face, but if you just want to include your GPS in the photo that’s fine too.
PLEASE SEND ME THE ANSWERS TO #1-3 BEFORE YOU LOG THIS CACHE. OTHERWISE I WILL HAVE TO DELETE YOUR LOG!!
This earthcache has been created with permission from Mendocino County General Services Agency, the division of Mendocino County which oversees Low Gap Regional Park.
References to further your knowledge:
http://en.wikipedia.org/wiki/Serpentinite
http://en.wikipedia.org/wiki/Serpentine_group
http://www.conservation.ca.gov/cgs/information/publications/cgs_notes/note_14/Pages/Index.aspx
http://en.wikipedia.org/wiki/Serpentine_soil