Suggested reading
Piero Barale, UN REBUS AI PIEDI DEL MONVISO RIFERIMENTI ASTRONOMICI
EMERSI DA ALCUNE INCISIONI RUPESTRI DELLE ALPI SUDOCCIDENTALI
The Po valley that, detaching from the Monviso, is the most important way to
get to this impressive mountain, had to favour different religious events as shown
by the still existing rock-engraving symbolizing the ancient people who pray.
These ancient cultural events have shown interesting astronomical
characteristics proving how the correlation between rock-engraving and the sky
observation during special periods of the year could be closed.
From the ideal centre from where the rock-engravings start, it seems it could be
possible to fix with great precision the changing of the seasons.
Furthermore, the users of this supposed “natural calendar” could get
information about the moon position during particular periods of its cycle;
situation that has always aroused great interest.
http://www.brera.unimi.it/sisfa/atti/1997/Barale.pdf
"La valle Po, già frequentata nel Neolitico20 dai “cercatori della pietra verde” -
(Pirosseni-Giadeite) materiale litico di elevata durezza che veniva estratto nei
depositi alluvionali della valle-, vedrà forse apparire le prime rappresentazioni
rupestri con la fine dell’età del Rame - inizio età del Bronzo. Ma con molta probabilità
il periodo di massimo sviluppo e popolarità del fenomeno si avrà solo
nell’età del Ferro. "
see also
http://stretchingtheboundaries.blogspot.it/2013/03/monte-viso.html