JURASSIC PERIOD: - from
208 to 144 million years ago.
|Wet and warm everywhere. No polar ice.
Gondwana and Laurasia. Stretching and rifting begin about 150 m.y.a.
Ancient flora only
- conifers, ferns, cycads, gingkos, lycopods,
CRETACEOUS PERIOD: - from 144 to 65 million
years ago. (A Gondwana Connection?)
|Climate:||Sudden cooling event and widespread flooding
by sea - Great Artesian Basin formed.
Between 100 and 80 m.y.a. the climate is mostly warm again.
From 80 to 65 m.y.a. a time of change.
Terminal Cretaceous Event 65 m.y.a.
Sudden cooling, many extinctions, volcanic activity, possibly caused by asteroid/comet impact.
|Continental Movement:||125 m.y.a. Africa leaves Antarctica.
India separates from Antarctica and Australia and bolts north at 20cm a
100 m.y.a. Africa separates from South America.
80 m.y.a. New Zealand separates from Australia.
|Australia:||Stretching and rifting. Australia stays attached to Antarctica long after other continents depart - Tasmania is the “problem”.|
|Tasmania:||Bass Strait Basin partly fills but does not quite split.|
|Vegetation History:||100 m.y.a. Flowering plants evolve in
West Gondwana. Great Rift valley between Africa and South America is
centre of evolution.
90 m.y.a. Flowering plants migrate to all continents and begin to compete with conifers etc.
80 m.y.a. First Nothofagus seen in Antarctica. Southern conifers still dominant in Australia - Huon Pine, Phyllocladus, Callitris. First Proteaceae in Australia. Nothofagus arrives via Antarctica and South America, but does not reach Africa.
Ilex is first flowering plant to occur in Australia.
TERTIARY PERIOD: - from 65 to 1.6 million
years ago, divided into five epochs;
Palaeocene, Eocene, Oligocene, Miocene and Pliocene
PALAEOCENE: - from 65 to 58 million years
ago. EOCENE: - from 58
to 40 million years ago.
|“A Golden Age” - mainly warm and wet
50 m.y.a. India collides with Asia and forms Himalayas
Seafloor spreading in Bight. Australia “un-zips” and finally separates from Antarctica 45 m.y.a.
Tasmania hangs on to Antarctica - Tasmania and South Tasman Rise continue to provide land connection to Antarctica until 45 m.y.a.
First occurrence of Casuarinas, Banksia, Myrtaceae,
Restioneaceae Winteraceae and Epacridaceae during Palaeocene.
: - from 40
to 24 million years ago.
|First glaciers on Antarctica. Cooler
and drier - more seasonal.
Drake Passage opens. Circum-polar current formed.
Australia colliding with New Guinea.
Carried north on Australian plate from about 65º S.
45 m.y.a. Australia departs with its cargo of Gondwanan
plants which now evolve in isolation for 30 million years.
- from 24 to 5.3 million years ago.
Australia and Tasmania:
|Warm and wet for a short period initially.
- 20 m.y.a. Isolation and cooling of Antarctica.
- 15 m.y.a. Southern ice cap formed.
- 10 m.y.a. Australia drying out and arriving in sub-tropics.
- 5.3 m.y.a. Terminal Miocene Event. Cold, dry, arid period
20 m.y.a. Antarctica stranded over South Pole - begins to cool.
Drifting north at 6-7cm/yr.
c.17 m.y.a. Antarctic flora succumbs to cold.
from 5.3 to 1.6 million years ago.
|Antarctica freezes over.
Brief warm period.
Northern ice cap forms.
Colliding with Timor region. Migration of plants and animals from north.
Gets to latitude 42ºS. Cool, temperate and moist.
5 m.y.a. Sub-tropical forest species migrate to refuges
in Queensland and New Guinea.
QUATERNARY PERIOD: - from
1.6 million years ago to present day, divided into two epochs;
Pleistocene and Holocene.
- from 1.6 to 0.1 million years.
|ICE AGE. Sea
levels rise and fall many times.
Climate drying. Man arrives c.60,000 years.
Intermittent land bridge across Bass Strait.
Man has major impact on flora. Rainforest reduced to 1% of land area.
HOLOCENE: The modern era - continental movement continues
(Return to the Story of Gondwana)