Equilibrioception is our sense of balance. It is perceived by the position of fluids in our inner ears. You can confuse it by spinning around and disrupting the fluid. Here is more information.
Balance? How many human senses are there, anyway?
Depending upon who you ask, there are between 9 and 21 human senses! (Little did I know. I have my work cut out for me with this series of caches.) Generally, for something to qualify as a sense, it requires a sense organ associated with it.
THE PUZZLE:
Look at the images (pic1 thru pic15) in the gallery to solve the puzzle. Checksum = 50.
THE ACTIVITY:
Next to the cache location you will find a spot where people balance rocks. I drive past this spot often, and I've never seen anyone there. But almost every day there is some change in the rocks. They fall, and then they are stacked up again.
There are five large base rocks. Don't destroy anyone else's work, but either add to or create a stack of rocks on one of the base rocks. If I see handiwork of note on my way to work, I'll stop, take a picture, and post it on the webpage.
UDATE: The mystery of the original rock balancer is solved. Check out VanWAMacer's log on Nov. 25th, 2006:
"very happy to find this cache. My father started "the stacking of the rocks" here over 23 years ago on his nightly walk with his dog Tonka. He also incorporated scrap lumber and other found items to make bridges and sculptures.People would leave letters for him thanking him for the smile his "tufa's" gave them. I live in Washington now and don't get back here as often as I would like, it sure was a pleasant surprise to see this site alive and kicking with such great energy!! Thank you! SL Macer & Jodiegirl"