Earth formed about 4.6 billion years ago from a ball of dust, rock, and ice in space. Its early atmosphere contained hydrogen, helium, ammonia, and methane before transitioning to one with carbon dioxide, water vapor, and nitrogen. Oxygen formed later through photosynthesis. Life first emerged over 3 billion years ago and has evolved through various eras, periods, and epochs defined by changes in Earth's atmosphere, climate, and biosphere as recorded in the fossil record. Modern humans evolved in the most recent epoch of the Quaternary Period within the current Cenozoic Era.

1. The evolution of life

2. Atmosphere
• Earth’s first atmosphere was hydrogen, helium,
ammonia and methane.
• Our second atmosphere consisted of carbon
dioxide ,water vapor and nitrogen.
• Oxygen formed later (photosynthesis)

3. Earths form
• Scientists hypothesize that Earth formed about
4.6 billion years ago
• They also believe that Earth started as a ball of
dust ,rock and ice in space, pulled together by
gravity

4. The evolution of life in the earth

5. The evolution of life in the earth

6. The evolution of life in the earth

7. The evolution of life in the earth

8. The evolution of life in the earth

9. The evolution of life in the earth

10. The evolution of life in the earth

12. Geologists divide the time
between Precambrian and
the present into three long
units called eras (Paleozoic,
Mesozoic, Cenozoic).
Eras are divided into periods
Periods can be further
divided into epochs
these subdivisions are based on
large scale events in Earth's
History that are identified
in the fossil record
and rock layers

13. PRECAMBRIAN TIME
• “
88%+ of Earths History
• 4.6 Billion Years Ago –
• 541 Million Years Ago

14. Precambrian Time - Hadean
Eon
• Rockless Eon
• The planet had formed
and was still very hot
• Began:4,6 Billion years
ago
• Ended:3,8 Billion years
ago

15. Precambrian Time – Archean
Eon
• At this time there were no
continents, just small
islands in a shallow ocean.
• Began: 3,8 Billion years ago
• Ended: 2,5 Billion years ago

16. Precambrian Time –
Proterozoic Eon
• The first invertebrate
organisms , animals
without backbones.
• Ediacaran fauna
• Began:635 million years
ago
• Ended:545 million years
ago

17. PHANEROZOIC EON
~570 Million Years Ago –
today

18. Phanerozoic
Eon
Paleozoic Era
Cambrian
Period
• Began:545 million years
ago
• Ended:495 million years
ago

19. Phanerozoic
Eon
Paleozoic Era
Ordovician
Period

20. Phanerozoic
Eon
Paleozoic Era
Silurian
Period
• .
• Began:443 million years
ago
• Ended:417 million years
ago

21. Phanerozoic Eon
Paleozoic Era
Devonian
Period
• Began:417 million years
ago
• Ended:354 million years
ago

22. Phanerozoic Eon
Paleozoic era
Carboniferous
period• Began:354 million years
ago
• Ended:290 million years
ago

23. Phanerozoic
Eon Paleozoic
Era
Permian
Period
• Began:290 million years
ago
• Ended:248 million years
ago

24. PHANEROZOIC EON
MESOZOIC ERA •
• Age of reptiles and
the dinosaurs
• Began: 248 Millions
Years Ago
• Ended: 65 Million
Years Ago

25. Phanerozoic
Eon
Mesozoic Era
Triassic Period
• Began:248 million years
ago
• Ended:205 million years
ago

26. Phanerozoic Eon
Mesozoic Era
Jurassic Period
• Began:205 million years
ago
• Ended:142 million years
ago

27. Phanerozoic Eon
Mesozoic Era
Cretaceous
Period
• Began:142 million years
ago
• Ended:65 million years
ago

28. PHANEROZOIC EON -
CENOZOIC ERA
• New mammals appeared while
others became extinct.
• The diversity of life forms
increased.
• Flowering plants became most
common.
• Humans are also part of the
most recent period of this era.
• Present day Earth is in this
era.
• A major geologic event of the
Cenozoic is the further
splitting and moving of
continents to their current
positions.
• 66 Million Year Ago
• now

29. Phanerozoic
Eon
Cenozoic Era
Tertiary
Period

30. Phanerozoic
Eon
Cenozoic Era
Tertiary
Period
Paleocene
Epoch• Began:65 million years
ago
• Ended:54.8 million years
ago

31. Phanerozoic
Eon
Cenozoic Era
Tertiary
Period
Eocene
Epoch• Began:54.8 million years
ago
• Ended:33.7 million years
ago

32. Phanerozoic
Eon
Cenozoic Era
Tertiary
Period
Oligocene
Epoch• .Began:33.7 million years
ago
• Ended:23.8 million years
ago

33. Phanerozoic
Eon Cenozoic
Era
Tertiary
Period Miocene
Epoch
• .
• Began:23.8 million years
ago
• Ended:5.3 million years
ago

34. Phanerozoic
Eon Cenozoic
Era
Tertiary
Period
Pliocene
Epoch
• Began:5.3 million years
ago
• Ended:2.6 million years
ago

35. Phanerozoic Eon
Cenozoic
Era
Quaternary
Period

36. Phanerozoic
Eon
Cenozoic Era
Quaternary
Period
Pleistocene
Epoch• Began:2.6 million years
ago
• Ended:11.7 thousand years
ago

37. Phanerozoic
Eon Cenozoic
Era
Quaternary
Period
Holocene
Epoch• Began:11.7 thousand years
ago
• Ended:Present day