The age of the sedimentary sequences of Hurd Peninsula (here referred to the Miers Bluff Formation (MBF), has been considered so far as Triassic, coeval of the Trinity Group. Recently, a Tithonian ammonite species was found in a non-
block, coming from the lowermost unexposed part of the Formation. Our micropal-eontological study reveals the occurrence of calcareous nannofossils in six sections. The recorded nannofossil association comprises the following species:
Micula decussata, Calculites obscurus, Arkhangelskiella cymbiformis, Prediscosphaera cretacea, Lucianorhabdus cayeuxii, Cyclagelosphaera reinhardtii, Braarudosphaera bigelowii, Ceratolithoides aculeus, Broinsonia
sp. indet. It determines a Campanian-Maastrichtian age for the middle and upper part of MBF. Two calcareous nanofossil species,
sp. indet., found in the Burdick Peak section suggest a Late Maastrichtian to (?) Paleocene age of the uppermost part of the MBF. The sediments of the MBF are possibly coeval of a part of Marambio Group (James Ross Island and Seymour Island) and Williams Point beds (Livingston Island).