Wow!
A huge Thank You! to all who responded. This is very helpful. I am glad this discussion might be seen by the GSA, which is where I have been searching the EarthCache sites through. Technically, the EarthCache shouldn't be leaving anything behind, only information about the geology of the site. But I could see why it would go unpublished for a variety of reasons mentioned.
Thank you again for all the information and happy EarthCaching!