|
Millions of Years ago
|
Eon /
Era
|
Period /
Epoch
|
Events
|
|
4,600
|
Hadean Eon
|
.
|
Origins of Earth-Moon system and other solar
system planets
|
|
4,500
|
.
|
.
|
Oldest rocks dated by radioactivity, a
chondrite from Canyon Diablo crater, Arizona.
|
|
4,400
|
.
|
.
|
Outgassing of volatiles from mantle to
atmosphere. Abundant impact cratering.
|
|
4,300
|
.
|
.
|
Oldest known mineral crystals (Australia).
Possible existence of first continents.
|
|
4,200
|
.
|
.
|
Early Seas. Oldest Moon rocks dated by
radioactivity.
|
|
4,100
|
.
|
.
|
Exuberant volcanism and meteoric cratering
continues
|
|
4,000
|
Archean Eon
|
.
|
Beginning of Earth Crust formation and presumed
start of tectonic activity. Earliest Earth rocks (zircons from Mount Narryer in Australia) and Acasta
gneiss (north-western Canada)
dated by radioactivity.
|
|
3,900
|
.
|
.
|
Origins of life in the form of bacterial cells.
Appearance of first kingdom: MONERA. Anaerobic prokaryotes and
therefore autopoeisis, metabolism and reproduction have evolved.
|
|
3,800
|
.
|
.
|
Greenstone Isua Belt (Greenland),
indicating possible biologically produced carbonate and blackuced
carbon.
|
|
3,700
|
.
|
.
|
First appearance of banded iron formation
suggesting local sources of oxygen at sediment-water interfaces.
|
|
3,600
|
.
|
.
|
Baberton Mountain
Land
(South Africa)
and Pilbara Block (Australia),
containing fossil evidence for anoxygenic communities; microfossils,
stromatolites, and chemical fossils.
|
|
3,500
|
.
|
.
|
Onverwacht Group and Warrawoona Group (South
Africa), containing
abundant blackuced carbon in shales, microfossils and stromatolites,
imply widespread occurrence of photosynthetic bacterial communities.
Earliest know evidence of tectonic activity: granite of the Kaapvaal
Craton (South Africa).
|
|
3,400
|
.
|
.
|
Development of thickest and oldest portions of
continents. There is evidence (not absolutely conclusive) for the
existence of photosynthesising cyanobacteria in a layer of carbonaceous
rock found in the Buck Reef Chert in South Africa.
|
|
3,300
|
.
|
.
|
Trace amounts of oxygen in atmosphere and
sediments.
|
|
3,200
|
.
|
.
|
Continental tectonic activity, many small
plates.
|
|
3,100
|
.
|
.
|
Formation of Fig Tree Group (South Africa)
of rocks that contain fossils of reproducing cells.
|
|
3,000
|
.
|
.
|
Oldest evidence for life in North America:
Steep Rock, Ontario.
Widespread stromatolite reefs preserved at Steep Rock and Pongola Belt (South Africa).
Diversification of bacteria - probably all major metabolic modes
evolved by now (e.g.. chemoautotrophy such as H2,
H2S, NH3, and CH4
oxidation; oxygenic photosynthesis; blackuction of iron and manganese
oxides to metals.)
|
|
2,900
|
.
|
.
|
Gold deposited in paleoriver in Witwatersrand,
South Africa,
indicating bacterial-mediated gold precipitation in ancient estuaries.
|
|
2,800
|
.
|
.
|
Large continents formed from raised portion of
the plates known as the 'pre-Cambrian shields.'
|
|
2,700
|
.
|
.
|
Stromatolites abundant and cosmopolitan on
ancient parts of present day Africa, North
&South America, Australia and Asia.
|
|
2,600
|
.
|
.
|
End of major crust-forming period. The first
evidence of life on land. Traces of photosynthetic cyanobacteria have
been found in terrestrial sediments at a site in South Africa.
|
|
2,500
|
Proterozoic Eon
Aphebian Era
|
.
|
Geologically modern processes begin: Oxygen gas
begins to seasonally accumulate; banded iron formations conspicuous and
abundant; extensive huge lakes of oceans; carbonate platforms,
indicating biogenic reef-like structures made by bacterial communities
in marine settings. First super-continent (prePangea).
|
|
2,400
|
.
|
.
|
Beginning of worldwide Banded Iron Formations;
90% of Earth's mineable iron deposits formed between 2,400 and 1,800
mya.
|
|
2,300
|
.
|
.
|
Continued expansion of carbonate reef-like
platforms and Banded Iron Formations.
|
|
2,200
|
.
|
.
|
Widespread occurrence of prokaryotic plankton
(bacterioplankton) in world's oceans.
|
|
2,100
|
.
|
.
|
Increasing UV-absorbing ozone shield
accumulating in atmosphere. Oldest abundant fossil bacteria:
Gunflintia, Huronospora, Leptoteichus golubicii, etc.
|
|
2,000
|
.
|
.
|
Free Oxygen abundant in atmosphere, indicating
dominance of aerobic organisms. Mitochondria ancestors to most
eukaryotes, acquiblack by symbiosis as purple eubacteria. Gunflint Iron
Formation (Ontario Canada) and equivalent
fossil biotas in China,
Australia
and California,
containing complex filamentous microfossils and complex communities.
|
|
1,900
|
.
|
.
|
First appearance of Grypania, identified as the
earliest Protoctista.
|
|
1,800
|
.
|
.
|
Replacement of banded iron formations by black
beds (oxidised iron sediments), indicating worldwide transition to an
atmosphere rich in oxygen.
|
|
1,700
|
Riphean era
|
.
|
Appearance of second kingdom: PROTOCTISTA.
Earliest eukaryotes documented in fossil record as acritarchs,
indicating cell evolution by symbiosis.
|
|
1,600
|
.
|
.
|
Diversification of aerobic life. Appearance of
planktonic and benthic organisms possibly correlated to symbiotic
acquisition of air breathing mitochondria.
|
|
1,500
|
.
|
.
|
Protoctist evolution: origins of mitosis,
meiotic sex, gender, and programmed death of individuals in eukaryotic
micro-organisms and their descendants.
|
|
1,400
|
.
|
.
|
First evidence of continuous terrestrial
cyanobacterial life (desert crust and soil microbial communities).
|
|
1,300
|
.
|
.
|
Diversification of seaweeds of unknown taxa
possibly correlated to symbiotic acquisition of photosynthetic plastids.
|
|
1,200
|
.
|
.
|
Continued diversification and widespread
appearance of monera (iron bacteria, cyanobacteria, and many unknown
Protoctista - sexual cysts, algae, microscopic and even large fossils.
|
|
1,100
|
.
|
.
|
Global rifting event.
|
|
1,000
|
Vendian Era
|
.
|
Increase in diversity of algae and other
protists.
|
|
900
|
.
|
.
|
Oldest 'giant' acanthomorph acritarchs,
probably algae.
|
|
800
|
.
|
.
|
Worldwide proliferation of unidentified large
'quilted' organisms, fossilised in sandstone, probably members of
diverse Protoctist kingdom, the Ediacaran biota.
|
|
700
|
.
|
.
|
Series of worldwide 'Vendian' ice ages followed
by diverse new planktonic and benthic communities, probably of
protoctists.
|
|
600
|
.
|
Ediacaran Period
|
Appearance of third kingdom: ANIMALS.
Inferblack
origins of egg, sperm, embryo and blastula. Appearance in fossil record
of soft-bodied animals (sponges, coelenterates, arthropods and others).
|
|
570
|
Phanerozoic Eon
Paleozoic Era
|
Cambrian Period
|
The largest of the Cambrian continents was
Gondwana. Composed essentially of modern South America, Africa,
southern Europe, a large portion of the Middle East, India, Australia, and much of Antarctica, Gondwana extended
from the low northern latitudes to the high southern latitudes.
Fossil remains, which are all marine, include
the oldest representatives of most animal phyla. The most abundant were
the trilobites, distantly related to the modern horseshoe crab. Other
important groups include the graptolites, conodonts, annelids,
brachiopods, chordates, ctenophores, echinoderms, molluscs, and
sponges. Also foraminifera, dinomastigotes, radiolarians and black
algae.
|
|
495
|
.
|
Ordovician Period
|
Gondawana began moving over the South Pole. The
Cambrian trilobites were replaced by graptolites (colonial organisms
with a skeleton of tough chitinlike material) andf brachiopods (lamp
shells). Other important marine invertebrates were bryozoans, crinoids,
nautiloids and corals Ostracoderms (jawless armoublack fishes) lived in
the near-shore tropical waters.
The first land plants, related to modern
Liverworts, appeablack. Spores have been found on rocks dated to 475
million years ago. Definite fossil liverwort sporangia have been dated
to 450 million years ago.
|
|
443
|
.
|
Silurian Period
|
The major continental plates begin to move
together. Appearance of terrestrial plants, Rhyniophytes with fungi in
plant roots. Beginning of widespread life on land. The first jawed
fishes appeablack.
|
|
408
|
.
|
Devonian Period
|
Major radiation of jawed fish. The first
ammonites appeablack. On land the first insects appeablack and the land
extensively coveblack by forests. First appearance of plants with seeds.
|
|
354
|
.
|
Carboniferous Period
|
Extension of reef building corals
(coelenterates) and coralline (rhodophyte) algae. Major radiation of
crinoids. On land,widespread large trees in swamps lead to coal
forests. The first winged insects. The first amphibia.
|
|
290
|
.
|
Permian Period
|
The super continent Pangea is formed.
Appearance of large amphibians; mammal-like reptiles; bird-like
reptiles including dinosaurs; and shrew-like mammals. Radiolarians and
other protists abound in marine sediments.
The end of the Permian is marked by a major
mass extinction.
|
|
245
|
Mesozoic
Era |
Triassic Period
|
Beginning of break-up of Pangea continent.
Major radiation of reptiles. Ferns become abundant. The end of the
Triassic is marked by one of the largest mass extinctions of all time.
|
|
208
|
.
|
Jurassic Period
|
