From Greenhouse to Icehouse – The Eocene/Oligocene - UMass ...

328 J. E. Francis et al.
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Hemisphere angiosperm families, including the Proteaceae, Myrtaceae and
Lauraceae, are also represented. The macrofossil record has largely been
described from isolated collections, even of single leaves in cores, and
although reasonably dated as a whole, a comprehensive understanding of
stratigraphic relationships between the floras, particularly in the Antarctic
Peninsula region, is at present hampered by differing stratigraphic
interpretations.
8.3.2. Antarctic Peninsula: King George Island
Many macrofloras have been discovered on King George Island in the South
Shetland Island group, north of the Bransfield Strait in the Antarctic
Peninsula region, currently dated between Late Palaeocene and Late Eocene
in age. The floras may have lived at a palaeolatitude of B621S, similar to its
present-day location (Lawver et al., 1992). The stratigraphy is complex
because Birkenmajer (1981, 1989, 1990) and Birkenmajer et al. (1986) erected
many local formations in comparison to a simpler scheme created by Smellie
et al. (1984). No single stratigraphic scheme exists and so the relationship
between the floras is confusing. The stratigraphic framework used here
includes both schemes (also reviewed by Hunt, 2001). Leaf macrofloras,
currently understood to be of Late Palaeocene to Middle Eocene in age, have
been described in varying completeness from the Admiralty Bay and Fildes
Peninsula areas of the island.
In the Admiralty Bay area, the Middle Eocene Mt. Wawel Formation
(Point Hennequin Group) contains the macroflora deposits collectively
known as the Point Hennequin Flora with individual localities named Mount
Wawel and Dragon Glacier Moraine floras (Zastawniak et al., 1985;
Birkenmajer and Zastawniak, 1989a; Askin, 1992; Hunt, 2001; Hunt and
Poole, 2003). The Mount Wawel flora comprises macrofossils of Equisetum
(horsetail), ferns and several Nothofagus species as microphyllous leaves
(a leaf-size category of 2.5–7.5 cm long), in addition to a few other
angiosperms and Podocarpaceae. The Dragon Glacier Moraine flora is
similar, the angiosperm leaves being dominated by Nothofagus and the
conifers including Araucariaceae and Cupressaceae, in addition to Podocarpaceae.
The Middle Eocene Petrified Forest Creek flora from the
Arctowski Cove Formation and the Late Eocene Cytadela flora from
the Point Thomas Formation are both within the Ezcurra Inlet Group. The
former is a wood flora requiring revision, but intermediate Fagus–
Nothofagus-type species are recorded. The Cytadela leaf flora includes
ferns (including a Blechnum-affinity species), mostly small Nothofagus-type