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The mountain ridge between Valpelline and Valtournenche valleys (Western Italian Alps) consists of a high strain zone several kilometres wide in which basement and cover of the Dent Blanche and Mont Mary tectonic units (nappes of the Austroalpine domain) show complex interrelations. New detailed petro structural maps across the ridge help to update the structural and metamorphic evolution of these Austroalpine units. The Alpine imprint under blueschist facies conditions is evident only locally notably in shear zones. Such high strain zones developed in the basement and in a post Permian cover (Roisan metasedimentary Zone) where the polyphase Alpine overprint is strong. The pre Alpine structural and metamorphic evolution is commonly well preserved in many domains with little Alpine strain. The presented maps from 1:2500 to 1:20000 scales and cross sections are the primitive data source of this work. They synthesize the geological and structural setting of this area and improve knowledge of the Western Alpine evolution by attributing tectonic structures to the evolving Alpine metamorphic stages.