GEOLOGIC TIMEGrade 7 Science
PRE-CAMBRIAN TIME
3 very long Eons: Hadean, Archean and Proterozoic;
Covers 87% of earth’s history;
Formation of earth, volcanic activity;
Atmosphere and oceans formed;
PRE-CAMBRIAN TIME
A thick, stable crust was formed;
Oldest rock evidence = 4.3 billion years old;
Algae and bacteria were the first life forms;
Jellyfish and worms evolved towards the end of this time period.
PHANEROZOIC EON
Latest 13% of earth’s history; 3 smaller periods called “Era’s”
Paleozoic: “Age of Fishes” or “Age of Ancient Life”
Mesozoic: “Age of Dinosaurs” or “Age of Medieval Life”
Cenozoic: “Age of Mammals” or “Age of Recent Life”
PHANEROZOIC EON
PALEOZOIC ERA
“Age of Fishes” or “Age of Ancient Life”;
7 “Periods”, first is called the Cambrian, hence, all previous time is called the “Pre-Cambrian”
This first Era covers over half of the Phanerozoic Eon.
PHANEROZOIC EON
PALEOZOIC ERA
“Pangea” forms: Motion of the earths crustal plates brought much of the total land together and fused into a super-continent.
Era begins when animals first developed skeletons (exo-)
PHANEROZOIC EON
PALEOZOIC ERA Ends with major
catastrophe that wiped more species off the face of the earth than at any other time in history (Permian extinction: 95% of all species)
Scorpions and centipedes were the first animal to live on land.
Insects, fern-like plants and conifers (trees that have cones) developed.
PHANEROZOIC EON
MESOZOIC ERA
“Age of Dinosaurs” or “Age of Medieval Life”;
3 “Periods”: Triassic Jurassic Cretaceous
PHANEROZOIC EON
MESOZOIC ERA
Triassic Period: Pangea breaks
apart; Dinosaurs and
mammals first appeared.
PHANEROZOIC EON
MESOZOIC ERA
Jurassic Period: Rocky
Mountains form;
First birds appear.
PHANEROZOIC EON
MESOZOIC ERA
Cretaceous Period Flowering
plants appeared;
Period ends in a mass extinction
(by an asteroid???)
PHANEROZOIC EON
CENOZOIC ERA
“Age of Mammals” or “Age of Recent Life”;
2 “Periods”: Tertiary and Quaternary.
PHANEROZOIC EON
CENOZOIC ERA
Tertiary Period: Mountain
building: Andes, Alps,
Himalayan and Western North America
PHANEROZOIC EON
CENOZOIC ERA
Tertiary Period: Modern
mammals, new birds, first horses, saber-tooth tiger, whales, first elephants and mastodons.
PHANEROZOIC EON
CENOZOIC ERA
Tertiary Period: First Humans
“Ardi” (4.4 mya) (Ardipithecus
ramidus)
??? Ardipithecus kadabba 5.6 mya
PHANEROZOIC EON
CENOZOIC ERA
Quaternary Period: Ice Ages to the
present; Extinction of large
mammals such as wooly mammoths;
Modern humans appear and dominate.