The Age of the EarthSection 13-2, pages 272-277

Evidence in StoneThe evidence about the age of

the Earth that influences Darwin’s thinking came from two people:◦James Hutton◦Charles Lyell

Evidence in StoneEvidence given by James Hutton:

◦Earth has been gradually changed by forces of weather (rain, wind, heat, cold), and by volcanoes and earthquakes.

◦Because all of these things take time, the Earth has to be very old – much older than thousands of years.

Evidence in StoneEvidence given by Charles Lyell:

◦He agreed that the Earth changed over time.

◦Lyell argued that past events must always be explained by events that can be observed (the scientific method).

◦The Earth is moving and shifting due to changes in the Earth. An earthquake was actively observed off

the coast of South America during the Galapagos voyage.

Evidence in StoneUniformitarianism:

◦The belief that the Earth is shaped by slow moving forces over a very long period of time.

Evidence in StoneCatastrophism:

◦The belief that Earth was shaped by single world-wide events. i.e. Noah’s flood or Creation

Evidence in StoneOther evidence found by

geologists…◦Fossils!◦Fossils are the preserved remains of

ancient organisms.

Evidence in StonePetrification:

◦The replacement of dead tissue and organs by minerals that turn into rock. i.e. petrified wood

Evidence in StoneMolds:

◦When an organism dies in soft mud leaving an imprint after it decays.

Casts:◦When different types of materials fill a mold.

Evidence in StonePreserved Remains:

◦When an organism doesn’t decay but is perfectly preserved i.e. amber

The Geologic Time ScaleThe geologic time scale uses the

position of rock layers relative to each other.◦The lowest layers of rock are the

oldest and younger layers are farther up

◦The law of superposition

The Geologic Time ScaleThe geologic time scale is a form

of relative dating only, geologists don’t know how long exactly it took each layer to form, so they can’t exactly date the fossils found in them.