GEOLOGICAL TIME SCALE - Eon period and epoch.pptx

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 2 nd 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 2 nd 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 : Paleozoic era Mesozoic era 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 arachnide s 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 5 th 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 : MISSISIPIAN – spread of ancient shark. PENNYSLAVIAN – origin of first reptil e. 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 : TERTIARY PERIOD(63-11 mya ) 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.

19. PNEMONICS To remember era- Pre ss the pale button to mes sage to cen ter. Precambrian Paleozoic Mesozoic Coenozoic To remember periods Cam els o ften s it d own care fully per haps t heir j oints cre ek. Cambrian –the age of invertebrates Silurian Devonian – the age of fishes, abundant ferns carboniferous – age of amphibians, 1 st seed plants appeared, Permian – origin of conifers Triassic Jurassic – age of reptiles Crestaceous – dominance of flowering plants

20. To remember epoch P ut e ggs o n m y p late pl ease ho ney. Paleocene Eocene Oligocene Miocene Pliocene Pleistocene Holocene

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

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