This cache is an important regional geological feature. Unfortunately, it has also been the site of destructive teen-age parties and less-than-wholesome religious rituals that can't stand the light of day.
Fortunately, work has been underway to rehabilitate this cache so that it is closer to its natural state and provides a better home for endangered species.
This is also a major recharge feature for a large sequestering of dihydrogen monoxide. Please be careful not to do anything which would disturb this chemical, or a lot of us may get very thirsty!
To prove your find, please send me the name of this feature, as listed on the sign, and the word FRAGMENT in the last line of the sign hanging above it. Upon receipt of the answers, I'll send you a link with some photos of the restoration work.