I've seen the railroad use the bags of quickcrete around a sign post on my way home from work. It's been there for over a year and the bags still have paper on them.

If you go with limestone, it's wise to put down geotextile fabric first. The cost of the fabric is quickly offset by reduced replacement rock and it slows down the weeds a bunch.
Limestone border link http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=88094&fpart=1



"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge." Stephen W. Hawking