Most Iapetian geological features are named after characters and locations in the Old French epic poem The Song of Roland, specifically the English translation by Dorothy L. Sayers.
Craters Named impact craters are:
Montes A mons , pl. montes , is a mountain.
Regiones There is one named Iapetian regio (area of distinct albedo difference), Cassini:
Terrae There are two named Iapetian terrae (large 'land' masses).
The adjectival form of Roncevaux is Roncesvallian.
References
Mackey & Mackey, 1922, The Pronunciation of 10,000 Proper Names, Dodd, Mead & Co., New York
External links
USGS: Iapetus nomenclature JPL: Iapetus Global Maps