Geological Eras
Eon Era Period Epoch Began* Geology Life on Earth








































QUATERNARY Holocene 0.01 Glaciers recede;
our world emerges
Homo sapiens dominates
Pleistocene 2.00 Glaciation and melt
affect sea levels
Primitive man appears
TERTIARY Pliocene 5.1 Continents near their
present positions
Some extinctions;
primates flourish
Miocene 24.6 Sea levels continue to
fall; mountains erode
Grasses widespread;
grazing mammals
Oligocene 38.0 Sea levels fall;
new mountains form
Crabs and snails
appear; grasses appear
Eocene 54.9 Mountain formation
and glaciation
Whales, jungles established.
Mammals continue to develop
Palaeocene 65.0 Extensive land subsidence;
widespread volcanic activity
First primates appear;
giant reptiles disappear
on land and sea







CRETACIOUS Late 97.5 Extensive swamps;
limestone and alluvial
desposition. Continents
move apart
Turtles and rays appear;
flowering plants established;
dinosaurs disappear
Early 144
JURASSIC Malm 163 Mountain erosion;
limestone forms.
Atlantic Ocean opens
Marine reptiles and land
dinosaurs dominate.
First birds appear
Dogger 188
Lias 213
TRIASSIC Late 231 Extensive desertification,
turning to hot and wet conditons
Ichthyosaurs and crustcea
appear; mammals and dinosaurs
Middle 243
Early 248



















PERMIAN Late 258 Mountain formation;
glaciation in the
southern hemisphere
Deciduous plants appear;
reptiles and insects abundant
Early 286
CARBONIFEROUS Pennsylvania 320 New land rises from
the sea; extensive
swamps; coal formation
Amphibians; sharks;
evergreen forests;
reptiles; winged
insects appear
Mississippian 360
DEVONIAN Late 374 Continents collide,
raising mountain
ranges; seas deeper
and narrower
Abundant fish;
early sharks and amphibians;
leafy plants;
first insects appear
Middle 387
Early 408
SILURIAN Pridoli 414 Varying sea levels.
New mountain ranges
Large marine vertebrates;
first plants colonise the land
Ludlow 421
Wenlock 428
Llandovery 438
ORDOVICIAN Ashgill 448 Continental drift
and sedimentation
First vertebrates appear;
coral reefs develop
Caradoc 458
Llandeilo 468
Llanvirn 478
Arenig 488
Tremadoc 505
CAMBRIAN Merioneth 525 Extensive volcanic
activity and marine
Trilobites appear
St David's 540
Caerfai 590









VENDIAN   650 Warm with shallow seas Seaweed, algae and
invertebrates appear
RIPHEAN Late 900 Violent upheavals
and metamorphism
First marine life and fossils
Middle 1300
Early 1600
  2500 Carbonate sediments form First stromatolites appear


  4600 Crust and oceans form
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