"SteveB" wrote in message
...
sand dune sand and caliche.

Southwest?

Is there a danger of the chemicals leaching out from treated lumber or
railroad ties for garden beds? What if I put a liner?

I read this question alot here. Here are a couple links to help you make a
decision :

http://www.ecologycenter.org/factshe...ated_wood.html

http://www.naturalhandyman.com/iip/infxtra/infpre.html

Creosote:
http://waterquality.montana.edu/docs...wq_faq_3.shtml