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.