peripediment
/ˌpɛrɪˈpɛdɪm(ə)nt/Geomorphology
noun
A broad, gently sloping surface on detrital alluvium that either extends outwards from a mountain foot in an arid or semi-arid region or else smoothly continues the line of an intervening pediment.
Origin
1940s. From peri- + pediment.