Ppt is all about geological time scale that how the earth formed and what event earth has gone throughout the different eon period and epoch .

1. GEOLOGICAL TIME SCALE
SUBMITTED BY:
SHEETAL SINHA
M. Sc. ZOOLOGY 2nd SEM
GOVT. N.P.G. COLLEGE OF SCIENCE ,
RAIPUR CHHATTISGARH
GUIDED BY :
Dr. RENU MAHESHWARI

2. SYNOPSIS
• Introduction
• Division of earth
• Flow chart representation of geological time scale
• Detailed division of GTS into:
• Eon
• Era
• Period
• Epoch
• Digrammatic representation of GTS
• Pneumonics to remember GTS
• References

3. INTRODUCTION
 The zoological time scale (GTS) is a record of the life forms and
geological events in earth’s history .
 Scientists developed the time scale by studying rock layers and
fossils world wide.
 It is the system of chronological dating that classifies geological strata
(statigraphy) in time.
 It is used by geologists, paleontologists, geographers and other scientist
to describe the timing and relationship of events in geologic history.
 Radioactive dating helped determine the absolute division in the
time scale.
 The concerned authority for stratigraphical , geological, and
geochronical matter is International Commision on Statigraphy (ICS).

4. Giving time a name
 The largest sections are called “eons”.
 Eons are divided into “eras” (the 2nd largest section).
 “Eras” are divided into “periods”.
 Periods are divided into “epochs” which is smallest
unit of geological time scale.

5. Flow chart representation

6. EONS
 Largest ; most general division of time .
 2 eons.
 The eons are : cryptozoic eon (precambrian supereon ) eon and
phanerozoic eon.
 Precambrian and phanerozoic eon both consists of three eons eras
each .
 Cryptozoic eon consists : 1. hadean
2. archean
3. proterozoic
 Phanerozoic eon consists : 1. paleozoic
2. mesozoic
3. coenozoic
 Precambrian supereon is called as hidden eon while phanerozoic eon
is considered as visible eon.

7. PRECAMBRIAN SUPEREON is
broken into 3 eons
 HEDEAN EON (4.6 bya- 4bya)
• This era is marked by the heavy bombardment in earths surface.
• Asteroid impact can be seen.
• Extreme volcanism
• Temperature was 230c
• 27 atmospheric temperature
• No O2.
ARCHEAN EON (4.0 bya- 2.5 bya)
 Beginning of life.
 Single celled prokaryotes started originating.
 Still no traces of oxygen .
 10-100 AP.

8. PROTEROZOIC EON (2.5bya-600mya)
• Bacteria began producing O2.
• Eukaryotes formed.
Phanerozoic eon is divided into three era namely paleozoic, mesozoic,
and coenozoic which are further subdivided into their consecutive
periods.
**** MYA refers to millions year ago.
****BYA refers to billions years ago.

9. ERA
 Each eon is broken up into eras.
 Era is the second largest unit of geological time scale after the eon.
 Major eras are :
1. Paleozoic era
2. Mesozoic era
3. Coenozoic era
EON
PHANEROZOIC
Paleozoic Mesozoic Coenozoic
ERA

10. PERIODS
 Each era is divided into even more specific blocks of time called periods.
 Various geological events are associated with each periods.Periods of paleozoic era:
 CAMBRIAN PERIOD (600-500 mya)
 Started 600 mya.
 Maximum evolutionary process happened in this period.
 Trilobites are boundary between precambrian supereon and phanerozoic eon are considered
to be found in this period.
 No terrestial life.
 Most water inhabiting phyla of now days esrablished. (echinodermates, molluscans ,
poriferans etc.)
 Marine algae originated.

11.  ORDOVICIAN PERIOD(500-425 mya)
• First vertebrates developed (jawless fishes).
• First animal with bones.
• First coral.
• Terrestial life begun.
 SILURANIAN PERIOD (425-405 mya)
 First land plants developed.
 First air breathing animal made their appearance.
 Corals made huge reefs.
 Marine arachnides paved their foot.
 Rise of fishes.
 Origin of vascular plants.
***There had a mass extinction between the ordovician and silurian period. It is
believed to had a total 4 mass extinction till now and 5th is at the verse to
happened.

12.  DEVONIAN PERIOD( 405- 345 mya)
• Called as the age of fishes.
• Lung fishes and amphibians originated.
• Abundance of shark, rays.
• Trilobites declined, first forest plant established.
• Fern appeared, origin of modern vascular plants.
 CARBONIFEROUS PERIOD
This period is divided into two group :
1. MISSISIPIAN – spread of ancient shark.
2. PENNYSLAVIAN – origin of first reptile. Spread of amphibia, lizard, and
winged insects.
 PERMIAN PERIOD(280-230 mya)
• Trilobites dissapear
• First reptile (Cotylosaurus ) progress, Therapsid like
• mammal evolved.
**** Second mass extinction is observed by the end of permian period.

13. MESOZOIC ERA is further subdivided into three periods:
TRIASSIC PERIOD(230-180 mya)
• Primitive mammal like prototherian , monotremer appeared.
• First dinosaur – pterosaurus appeared.
• Extinction of primitive amphibian.
JURASSIC PERIOD(180-135 mya)
 Called as golden age of dinosaurus.
 First toothed bird appeared.
 Dinosaurs diversified.
 Insectivorous marsupials appeared.
 Flowering plants appeared.
 Ammonoites formed.
CRESTACEOUS PERIOD (135-65mya)
• Dinosaurus reached peak and became extinct.
• Toothed bird extinct, first primate, snakes, modern bird appeared.
• Archiac mammals became common i.e. marsupials and placental
mammals.

14. COENOZOIC ERA is bifurcated into two period :
1. TERTIARY PERIOD(63-11 mya)
1. QUARTENARY PERIOD(11mya to recent)
Tertiary period
Quartenary period
Coenozoic era

15. EPOCH
 This is the smallest unit of geological time scale.
 An epoch lasts several millions years.
 Tertiary and quartenary period of coenozoic era is
divided into 5 and 2 epochs respectively.

16. TERTIARY PERIOD is subdivided into 5 epochs:
 PALEOCENE EPOCH (63-58 mya)
• This epoch is marked by the development of primitive mammals.
• Palms , cacti and pines appeared.
• Primitive mammals are: credonts(a group of catlike and doglike animals).
 EOCENE EPOCH ( 58-36 mya)
• Placental mammals diversified.
• Flightless bird like Diatryma found.
• Hoofed mammals started forming. (like ungulates)
 OLIGOCOENE EPOCH (36-25 mya)
• Mammals continued to grow larger.
• Mammals like : Entelodont, Hyracodon, Titanothere were
at peak.

17. MIOCENE EPOCH ( 25-12 mya)
• Ancestors of modern man and monkey (Dryopithecus) appeared.
PLIOCENE EPOCH ( 12-11 mya)
• Man evolved.
• Horse and camel evolved.

18. QUARTENARY PERIOD is subdivided into 2 epochs
:
 PLEISTOCENE EPOCH (1-0.1 mya)
• Extinction of large mammals ,
• Evolution of modern human like: neanderthal
man , Homo erectus.
 HOLOCENE EPOCH (recent)
• This epoch is marked by the rise of human civilization.

20. PNEMONICS
 To remember era-
Press the pale button to message to center.
Precambrian
Paleozoic
Mesozoic
Coenozoic
 To remember periods
Camels often sit down carefully perhaps their joints creek.
Cambrian –the age of invertebrates
Silurian
Devonian – the age of fishes, abundant ferns
carboniferous – age of amphibians, 1st seed plants appeared,
Permian – origin of conifers
Triassic
Jurassic – age of reptiles
Crestaceous – dominance of flowering plants

21. To remember epoch
Put eggs on my plate please honey.
Paleocene
Eocene
Oligocene
Miocene
Pliocene
Pleistocene
Holocene

22. References
• Veer Bala Rastogi
• Youtube channel – Dr C. L. Verma
• Shutterstock
• https://www.digitalatlasofancientlife.org

23. THANKYOU