This cache IS located at the posted coordinates!! (It is a "mystery" cache because it is a challenge geocache and certain requirements have to be met before you can log your find. )
Have you ever geocached or letterboxed at over 10,000 ft elevation? If you have ever either found or planted either a geocache or a letterbox at any place 10,000 ft elevation or higher, then you can log this geocache as found by listing at least one such find or plant in your log post. It would be fun if you could list more than one if you have several, because this would give other geocachers a list of possible geocaches to go and find in order to fulfill the requirements of this challenge. Your 10k+ ft geocache or letterbox can have been found at any time: it does not have to be found after the publishing date of this geocache challenge: it could have been found years before.
In your log post, please indicate whether it's a geocache or letterbox you've found at 10,000 ft plus, and then for geocaches give either the geocache name or the GC number, find date if you can, and state the physical elevation of that geocache location. If you don't know the elevation, it's easy to find that using GoogleEarth: just do a search for the cache coordinates on GoogleEarth, then put your pointer on those coordinates, and it will tell you the elevation at that spot. For letterboxes, give the name of the letterbox found and state whether it is listed on Atlasquest (www.atlasquest.com) or LbNA (www.letterboxing.org), then state the elevation and how you know what the elevation was that box.
I'll begin: I found the geocache "John Says, 'Not Beyond THis Point' - 2" GC33GPY located at 10,311 ft (What my GPS read at the cache site) on 10/14/13. I also found "Mexican Mine Trail" GC2BXB1 at 10,124 ft (GoogleEarth) on 10/16/13. Then I planted the Atlasquest letterbox "Paiute Pass" located at 11,435 ft on 10/17/13. I know the elevation of the letterbox because I had my GPS with me to give me elevation data. All these are in California.
TO FIND THIS CACHE:
This geocache is located on El Toyonal Road in Orinda (it is about 20 ft from the road, and is accessible either by driving in from Orinda (in which case it's a park and grab), or walking in from Wildcat Canyon Rd. If you walk in from WIldcat Canyon Rd it's 0.5 mile beyond "The Road LEss Traveled" geocache, or a total of about 1.5 to 2 mile round trip walk, and there is another excellent and very creative multicache to look for on your way as well.
Conratulations to Berkeley Boomers on the FTF!