Geologic Time Scale

1
Geologic Time Scale

• An outline of the development of the earth and
  of life on the earth.

2
Geologic column

• ordered arrangement of rock layers based upon the
  ages of the rocks

3
How is a geologic column created?

• Dating rock layers from around the world and
  putting them together to create a standard
  arrangement.
• When rock layers from 2 places match- they were
  most likely formed at the same time!

4
Geologic time is divided into units

• changes in the earths surface or climate
• extinction of various species.

5
A unit of geologic time is often characterized by
fossils of a dominant life form. (ex. Below
Paleozoic fossils)
6
Era-largest unit of geologic time, there are 4
geologic eras

• Precambrian- oldest, longest (4 billion years),
  few fossils, important evidence to show that life
  began in the oceans
• Paleozoic- 325 million years long, ancient
  life or age of invertebrates
• Mesozoic- 180 million years long, middle life,
  more complex organisms, age of reptiles
• Cenozoic- 65 million years, recent life or
  age of mammals

7
Periods

• Eras are divided into periods, characterized by
  specific fossils, named for the place they were
  first discovered. (Devonian Devonshire,
  England)
• Ex. Cenozoic Era is divided into Tertiary and
  Quaternary periods

8
Epochs

• more detailed fossils (not deformed) in the
  Cenozoic Era allow scientists to break down the
  periods in this era only into smaller units
  called epochs.
• Ex. Quaternary Period is divided into the
  Pliestocene and Holocene epochs.

9
IF THE ENTIRE HISTORY OF THE EARTH WAS 1 YEAR

• The first organisms would have appeared in early
  May
• Early humans would have appeared on Dec 31 at 7
  pm.
• Modern humans would have appeared at 1155 pm.

10
Neanderthal Man Cro-Magnon Man
Modern Man
11
Theory of evolution

• theory that organisms change over time and that
  new organisms are derived from ancestral types.
• In examining and dating fossils to create the
  geologic time scale, geologists and
  paleontologists have found a large amount of
  evidence that supports this theory (proposed by
  Charles Darwin).

12
(No Transcript)