Chapter 3 : Earth Science

The Rock and Fossil Record

Earth Science : Chapter 3.1

Earth’s Story and Those Who First Listened

Objectives1. Compare uniformitarianism and

catastrophism.

2. Describe how the science of geology has changed over the past 200 years.

3. Explain the role of paleontology in the study of Earth’s history.

Scientist James Huttonauthor of Theory of the Earthproposed that geologic processes such as erosion

and deposition do not change over time.Uniformitarianism

the idea that the same geologic processes shaping the Earth today have been at work throughout Earth’s history.

The Principle of Uniformitarianism

Hutton’s theories sparked a scientific debate by suggestingThe Earth was much older than a few thousand years,

as previously thought.A few thousand years was not enough time for the gradual

geologic processes that Hutton described to have shaped the planet.

CatastophismPrinciple that states that geologic change occurs

suddenly.

Uniformitarianism Versus Catastrophism

Catastrophism was geology’s guiding principle until the work of geologist Charles Lyell caused people to reconsider uniformitarianism.

Lyell published Principles of Geology in the early 1830s. Armed with Hutton’s notes and new evidence of

his own, Lyell successfully challenged the principle of catastrophism.

A Victory for Uniformitarianism

During the late 20th centuryScientists such as Stephen J. Gould challenged

Lyell’s uniformitarianism.They believed that catastrophes occasionally

play an important role in shaping Earth’s history.

TodayScientists realize that most geologic change is

gradual and uniform, but catastrophes that cause geologic change have occurred during Earth’s long history.

Modern Geology -- A Happy Medium

The history of the Earth would be incomplete without knowledge of the organisms that have inhabited our planet and the conditions under which they lived.

PaleontologyScience involved with the study of past life

PaleontologistStudy fossils, which are the remains of organisms

preserved by geologic processes.

Paleontology -- The Study of Past Life