Palynological analyses of the Marambio Group sediments of Humps Island (Santa Marta and López de Bertodano formations) indicates that there is minor displacement across a prominent NW–SE trending normal fault which passes beneath the southern bluff. No major compositional differences were perceived between the palynomorph assemblages either side of the fault. A late Campanian age is suggested for both sequences, based on comparison with Australasian dinoflagellate cyst zonations. A new species of the dinoflagellate cyst Bourkidinium has been recorded from strata on either side of the fault. A significant number of recycled Permian and Early Cretaceous palynomorphs were recorded. Most are miospores and exhibit significant variation in preservational states, implying derivation from several sources. More thermally mature Permian gymnosperm pollen is most likely derived from the nearby Trinity Peninsula Group, exposed on the Antarctic Peninsula. The source of the relatively well preserved Permian pollen is problematic.

Thirty samples from two sections on south-western Humps Island, James Ross Basin, northern Antarctic Peninsula, contain moderately diverse dinoflagellate cyst assemblages deposited in shallow shelf, open marine conditions. Assemblages contain common Isabelidinium spp., including I. cretaceum and I. pellucidum, Cerodinium diebelii, common Odontochitina spp., including O. operculata, O. porifera and O. spinosa, plus Nelsoniella cf. aceras, Octodinium askiniae and rare Chatangiella tripartita, C. victoriensis, Isabelidinium cf. belfastense and I. korojonense. This association includes species with Santonian and Campanian (to Maastrichtian) distribution in Australia and New Zealand. Some of these species may be recycled. A Campanian age is suggested for the Humps Island sections.