The Cainozoic geology of Flinders Island, Bass Strait

Cainozoic sediments and volcanic rocks superficially
overlie the mountainous Palaeozoic basement of Flinders
island and mainly form the coastal plains.
Marine deposits include Middle Pliocene to Recent
near-shore and littoral coquinoid beds, and some
Quaternary beds appear related to old marine stands
at about 15-18 m., 4.5-6 m. and 0.6-1.5 m. above
MHWS. Quaternary dune deposits afe predominantly
calcareous on the west coast and predominantly siliceous
on the east coast, and show varying degrees of consolidation
and soil development generally related to
age. A Recent beach ridge and coastal barrier system
is developed and lagoonal deposits include Pleistocene
limestone and Recent peat. Non-marine gravel and grit
deposits (including st.anniferous and sub-basaltic deposits)
were sometimes reworked by later marine incursions.
Scattered volcanic rocks include tuffs, alkali olivinebasalts
and olivine-nephelinites, erupted from several
centres roughly aligned along a north westerly trend.
The volcanism was largely Tertiary in age and some
lavas are lateritised.
The Cainozoic history was initiated by faulting, tilting
and uplifting of the Flinders Island block by early
Tertiary time, with subsequent volcanism. During the
Cainozoic, alternations of predominantly terrestrial or
marine erosion and deposition on Flinders Island were
related to fluctuating sea-levels, which influenced some
faunal movements.