The document explains the geologic time scale, detailing the Earth's history through rock records that contain fossils. It describes the main eons, eras, periods, and epochs, along with the methods of relative and absolute dating used to establish this timeline. Significant events and life forms are highlighted from the Hadean eon to the Quaternary period, showcasing the evolution of life and major extinctions.

1. GEOLOGIC TIME SCALE
Eleanor L. Cabungcag
Science Teacher,SHS

2. GEOLOGIC TIME SCALE
The age of Earth is recorded on rocks
which contains the remains and
traces of plants and animals that
have lived and died throughout
Earth’s History (fossils).
Rock records are illustrated on a
timeline called the Geologic time
Scale.

4. GEOLOGIC TIME SCALE
It is subdivided into hierarchal intervals,
the largest being EON, followed by
ERA, PERIOD, and EPOCH, respectively.
Subdivision of Geologic Time is based
from significant events in the Earth’s
History as interpreted from the rock
record.

5. How the time is scaled?
To establish the time scale,
scientists considered correct
succession of rocks which is
achieved through RELATIVE and
ABSOLUTE DATING TECHNIQUES.

6. TYPES OF DATING
ABSOLUTE DATING-scientists could assign specific
time units to mineral grains within a rock. It uses four
methods, namely: radiometric dating; amino-acid
dating; dendrochronology, and thermo-
luminescence.
RELATIVE DATNG-it is based on the principle of
superposition. The layers on the bottom are said to
be the oldest and the layers above are the younger,
fossils that are found on the same layer are groups
that have lived together.

7. RELATIVE DATING

8. TYPES OF ABSOLUTE DATING
RADIOMETRIC DATING DENDROCHRONOLOGY
 Dates fossils through
determining the date
where the last time they
are heated.
 Method used to date
rocks and other objects
based on the decay rate
of radioactive isotopes.
AMINOACID DATING
 Determines the changes
in amino acid structure in
a specimen to date
fossils.
THERMOLUMINESCENCE
 Tree rings are examined
to date the exact year
they were formed.

9. GEOLOGIC TIME SCALE
FOUR MAJOR EONS
HADEAN EONS 4.57 bya
This is the time that the Earth was just being formed. There
were a lot of objects that hit the Earth that made it very
hot.

10. ARCHEAN EON 3.85 bya
The rise of the single-celled organism can thrive in
methane and ammonia. Cyanobacteria form stromatolites
and used photosynthesis that produced the first oxygen in
air. The first oxygen caused the first rusted iron in rocks.

11. PROTEROZOIC EON 2.5 bya
Free oxygen in atmosphere produced
significantly. First oxygen animals occurred.

12. PHANEROZOIC EON 540 mya
Visible life, contains evidences of the life forms that we are
familiar today.

14. PALEOZOIC ERA

15. CAMBRIAN PERIOD 540 mya
Named after Cambria, Wales
Set peak for arthropods (ancestors of insects and
crustaceans) and chordates.

16. ORDOVICIAN 488 mya
Gave rise to trilobites, jawless fish, mollusks, and
corals.

17. SILURIAN PERIOD 444 mya
Diversification of jawed fish and bony fish. Multi-cellular life
also began to appear in land in the form of small
bryophyte like and vascular plants.
Terrestrial arthropods also occurred.

18. DEVONIAN PERIOD 416 mya
Named after Devon, England where fossils are found.
Showed development of ferns, and first trees, animals
called tetrapods (first vertebrate to live on land) which has
lizard or snake-like structure, and the spiders.

19. CARBONIFEROUS PERIOD 359 mya
Gave rise to conifers, dragonflies, and widespread of
cockroaches. Trilobites evolved to fish, and tetrapods
evolved to marine reptiles: lizards and snakes and
archosaurs: the ancestors of crocs and dinosaurs.

20. PERMIAN PERIOD 299 mya
Flourished by coral reefs and herbivores. Mass extinction
happened.

21. MESOZOIC ERA

22. TRIASSIC PERIOD 251 mya
Gave rise to reptiles and first dinosaurs.

23. JURRASIC PERIOD 202 mya
Rise of birds and mammals.

24. CRETACIOUS PERIOD 146 mya
Known for its iconic dinosaurs such as Triceratops and
Pteranodon. Plants become very abundant and very tall
allowing animals to surge in height as well.

25. MESOZOIC ERA

26. PALEOGENE PERIOD 66.5 mya
Mammals that survived mass extinction in Cretaceous
Period thrived. Rodents, small horses, rhinoceroses,
elephants, dogs, cats, pigs and large flightless birds thrived.

27. NEOGENE PERIOD 22.3 mya
Gave rise to early primates including early humans, and bovids such as sheep,
goat, antelope and gazelle.

28. QUARTERNARY 2.6 mya
Gave rise to the cave lions, saber-toothed cats, cave
bears, deer, woolly rhinoceroses, and woolly mammoths.
Plant life flourished because of the extinction of dinosaurs
which include pines, oaks, mosses, grasses, flowering and
edible crops. Sharks, whales and other marine life.

29. Thank You for listening!