This cache IS located at the posted coordinates!! (It is an "unknown" cache because it is a challenge geocache and certain requirements have to be met before you can log your find.)
Have you ever geocached at over 7000 ft elevation? If you have ever found a geocache at any place 7000 ft elevation or higher, then you can log this geocache as found by listing at least one such find 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 7k+ ft geocache 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 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. Alternatively, you can use Geocaching Swiss Army Knife to find the elevation, at www.gsak.net.
You can list the same 10k plus elevation geocaches for all 4 challenge caches, or list lower elevation caches for those challenges where they apply. Some geocachers may have dozens if not hundreds of caches that fit some of these challenges; you need not log all the caches that meet the challenge unless you want to.
Example: 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.
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 0.85 mile in from the parking area on Wildcat Canyon...there is a gate and you have to walk in on El Toyonal. You might want to bring carrots as there are often two horses in the corral just across from this geocache.