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Science Summaries
Geology

Geologic Time Summary
Rock Types
(This page is not intended
for small screens.)

by Vaughn Aubuchon

This simplified geology chart summarizes the eras, periods, and epochs of geologic time. Included is a chart of the 4 main types of rock.

Geologic Time Chart

Four Main Types of Rocks

Mohs Hardness Scale

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Geologic Time Summary Chart

Era
Period
Epoch
Con-
ditions
Dur-
ation (millions years)
Years Since (millions of years)
Evolution of Life
Animals . . . . . . Plants

 

 

 

 

 

 

 

0

 

 

 Cenozoic (1st) (65M)

Quarternary

7. Holocene

 

10K

10K

 

Man

 

 

 

 

0.5

 

 

 

6. Pleistocene

icy

2

0 - 2

 

 

 

 

2

 Tertiary
Neogene (25M)

5. Pliocene

cooler, dryer

11

2 - 13

 

Mammals increase

 

4. Miocene

 

12

13 - 25

 

Grazing animals

Grasses

3. Oligocene

 

11

25 - 36

 

Saber-toothed cats

 

Paleogene (40M)

2. Eocene

 

22

36 - 58

 

Horses

 

1. Paleocene

 

7

58 - 65

 

Birds, mammals

Flowering plants

65

Mesozoic (2nd) (160M)

3. Cretaceous

 

 

71

65 - 136

 

Dinosaurs dissappear

2. Jurassic

 

 

54

136 - 190

 

Dinosaurs rule

Conifers

1. Triassic

 

volcanic

35

190 - 225

 

Dinosaurs appear

 

 

225

Paleozoic (3rd) (375M)

6. Permian

 

 

55

225 - 280

 

Many reptiles

 

5. Carboniferous

 

 

(65)

 

 

 

 

280

 

Pennsyl-
vanian

 

warm, swampy

30

280 - 310

 

Reptiles

 

 

Missis-
sippian

 

land increase

35

310 - 345

 

Amphibians, insects

 

4. Devonian

 

 

60

345 - 405

 

Fish

 

3. Silurian

 

 

20

405 - 425

 

Air-breathing animals

Spore land plants

2. Ordovician

 

 

75

425 - 500

 

Seaweed

 

1. Cambrian

 

 

100

500 - 600

 

Marine Invertebrates

 

 

600

Pre-cambrian

2. Proterozoic

 

 

900

600 -
1,500

 

Primitive invertebrates

Marine plants

1. Archeozoic

 

granite, gneiss crust formed

2,500

1,500-
4,000

 

One-celled organisms

Algae

 

4,000

60

100

60

80

80

50

50

40

110 - 730

100



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The Four
Main Types of Rocks

Description
Examples

Igneous

Volcanic rock that is ejected from a volcano - fast cooling

lava, obsidian, pumice

Plutonic

Intrusive volcanic rock that is NOT ejected from a volcano - slow cooling

basalt, diorite, gabbro, granite

Sedimentary

Layered by accumulated sediments

breccia, chert, flint, limestone, shale

Metamorphic

Sedimentary or igneous rock transformed by intense heat and pressure

coal, gneiss, marble, schist, slate

100

250 - 500

150



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Mohs Hardness Scale

Mohs
Scale
Absolute
Hardness
Mineral

Examples

1
1

Talc

-

2
3

Gypsum

Fingernail

3
9

Calcite

Copper penny, gold, silver

4
21

Fluorite

Iron, platinum

5
48

Apatite

Steel - hard enough for gems

6
72

Feldspar (Orthoclase)

Glass, pyrite

7
100

Quartz

Scratches glass

8
200

Topaz

Emerald, aquamarine

9
400

Corundum, Sapphire, Ruby

Twice as hard as topaz

10
1,500

Diamond

4 times as hard as corundum

60

60

130

250 - 500



DISCLAIMER
Although the author has tried to be as accurate as possible, errors are possible.

I could not find a simplified online geology table like the above. So, I made this geology chart, to help myself understand the relationships between the eras, periods, and epochs. I hope that it helps you.

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This Vaughns Geology Summary page
was last updated on 2017-10-28.