Paleontology is the study of past life through the examination of plant and animal fossils. Paleontologists study fossils and the environments they formed in to piece together details about past ecosystems. The principle of uniformitarianism, first developed by James Hutton in 1788, holds that the same geological processes shaping Earth today have operated throughout its history. This theory helped establish that Earth is much older than previously believed. Relative dating methods like the law of superposition and use of index fossils allow paleontologists to determine the sequential order of geological events and changing life forms without knowing exact time periods.

1. I. What is Paleontology?
The study of
past life.

2. I1. Paleontologist
□ Paleontologist –
scientist who studies
fossils and plants
from past life and
other past
ecosystems
□ Studies traces left
behind by animals
and piece together
the conditions under
which fossils were
formed.

3. III. Uniformitarianism
□ Uniformitarianism –
the idea that the
same geologic
processes shaping
the Earth today
have been at work
throughout Earth’s
history.
□ This takes a LONG
time!

4. Extra Info!
James Hutton was the
first to develop the
idea of
Uniformitarianism in
1788
His theory sparked a
scientific debate by
suggesting that Earth
was much molder
than previously
thought!

5.  Rocks record geological events and
changing life forms of the past.
 We have learned that Earth is much older
than anyone had previously imagined
Continued
 There are two ways that we can determine
the age of a rock:
1. Relative Dating
2. Absolute Dating

6. IV. Relative Dating

7. Relative dating
tells us the
sequence in which
events occurred,
not how long ago
they occurred.
Chronological order
- relational

8. a. Law of Superposition
The law of superposition states that in an
undeformed, undisturbed sequence of
sedimentary rocks, each bed is older
than the one above it and younger than
the one below it.

9. Undistrubed Rock Layer

10. Distrubed Rock Layer

11. b. Original Horizontality
The principle of original horizontality
means that layers of sediment are
generally deposited in a horizontal position.

12. c. Index fossils
• Index fossils are used to determine
approximate age. Index fossils are
widespread geographically, are
limited to a short span of geologic
time, and occur in large numbers.
FOUND IN SEDIMENTARY ROCKS

13. Index Fossils

14. d. Geological Column
Geologic column is an ideal sequence
of rock layers that contains all the
known fossils and rock formations on
Earth arranged from oldest to
youngest.

16. Ticket out the
Door!
What is
Uniformitarianism?