The O.S. Gray Natural Area is a hidden gem of Arlington. The amount of work the friends of the O.S. Gray Natural Area do for this area is remarkable. If they are out there working when you are seeking this, please compliment them . . and you may need to explain what you are doing, not all of them are familiar with Geocaching.
A nice medium length walk in some lovely woods. Cache is medium to small. Please examine how the cache is hidden and leave it just as you found it.
The hint gives it away, so try it without . . . but I didn't want you to walk all the way out here and not find it . . . .