In reply to Mapleleaf:
I found this to be very useful and includes stuff that doesn't feature in the two guides mentioned above:
http://www.montagneinvalledaosta.com/SITO/pagina_6_ghiaccio_menu/pagina_6.h...
Google Translate will sort out any language issues.
In addition, there's a load of stuff available on-line. Just google "Cascate di ghiaccio Cogne/ Valsavarenche/ Aosta" (or wherever). The info's virtually all in Italian - but easily translated as above.
HTH
Dave