Geological Time Circle [journal]

The position on a clock can represents a location in time. You can place important events in earth history on a 12-hour time circle by drawing a letter or a small picture/icon in the right time position.

Before you start, or read further, write down your prediction of when humans appeared in the time line.

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I. The First Eleven Hours

A 4,500 million years (00:00)

The Earth is formed.

B 4,300 million years (FIRST EVENT) (00:32)

Radioactive and gravitational heating release water, and gases --methane, ammonia, hydrogen, nitrogen, and carbon dioxide.

C 3,800 million years (1:52)

Water in the atomosphere cools and condenses into oceans.

D 3,500 million years (2:40)

The first LIFE appears--microscopic bacteria, the simplest form of life known today or in the past. The first photosynthesis begins as tiny algae emit oxygen into the atmosphere, strengthening the ozone layer.

E 1,500 million years (8:00)

The first multicellular organisms appear.

F 545 million years (10:32)

First hard-bodied organisms appear. Until now, nearly all organisms had been microscopic.

G 500 million years (10:40)

The first fish, which are the first creatures to have backbones.

H 430 million years (10:51)

Algae begin to live on land.

I 420 million years (10:52)

Millipedes are the first land animals.

II. The Eleventh Hour

Do the same for events in the last hour.

J 375 million years (11:00)

The first primitive sharks.

K 350 million years (11:04)

The first amphibians, insects, and ferns,

the first plants with roots.

L 300 million years (11:12)

The rise of reptiles.

M 250 million years (11:20)

The Permian mass extinction.

N 225 million years (11:24)

The first dinosaurs.

O 200 million years (11:28)

The supercontinent Pangaea starts to

break up as the first mammals appear.

P 136 million years (11:38)

The first primitive kangaroos.

Q 65 million years (11:49)

The dinosaurs become extinct.

R 55 million years (11:51)

Rabbits evolve.

S 20 million years (11: 57)

Chimpanzees and hominids evolve.

T 4 million years (11:59 and 39 seconds)

Human ancestors stand up.

U .05 million years (11:59 and 59 seconds)

Homo sapiens, our species, exists.

V .01 million years (11:59 and 59.5 seconds)

First permanent human settlements and

the first use of fire to cast copper and harden pottery.