Transcript Geologic Time Powerpoint Chapter 4

A Trip Through Geologic Time
Table of Contents
Fossils
The Relative Age of Rocks
Radioactive Dating
The Geologic Time Scale
Early Earth
Eras of Earth’s History
Fossils
Wyoming, 50 Million Years Ago
Today, Wyoming has areas of dry plateaus, but 50 million years ago it
was very different.
The Relative Age of Rocks
The diagram below shows rock layers found at a site. Identify the area
on the diagram that shows an intrusion. What is the oldest layer of rock
in the diagram?
The Relative Age of Rocks
Index Fossils
Scientists use index fossils to match rock layers. Match the rock layers
in locations 2, 3, and 4 with first area shown. Which fossils can be used
as index fossils?
The Relative Age of Rocks
Unconformities
and Folding
What are the oldest and
youngest layers
in the last two
diagrams? Identify the
unconformity. Which is
the part of the fold that
is overturned?
Radioactive Dating
Half-Life
The half-life of a radioactive element
is the amount of time it takes for half
of the radioactive atoms to decay.
What pattern do you see in the graph?
Use the pattern to complete the last
bar.
Radioactive Dating
Elements Used in Radioactive Dating
The Geologic Time Scale
Earth's History in a Day
If all of Earth's 4.6-billion-year history could be squeezed into one 24hour day, it would have been a timetable something like this.
The Geologic Time Scale
The Geologic Time Scale
The divisions of the geologic time scale are
used to date events in Earth’s history. What
is the duration of each period?
Early Earth
Early Earth
This artist’s illustration shows Earth shortly after the moon formed.
Earth was hot and volcanic, and contained no liquid water. The moon
was much closer to Earth than it is today. Over time, Earth’s surface
began to cool, forming solid land.
Early Earth
Development of the Atmosphere
The illustration shows the difference between Earth’s first and second
atmospheres. What is the missing information for each atmosphere?
Eras of Earth’s History
Cambrian Life
The illustration shows one artist’s
idea of what Anomalocaris (the
large organism) and other
organisms looked like.
Eras of Earth’s History
Changing Landscapes
How do the organisms of each period differ and what are their
characteristics?
Eras of Earth’s History
The illustrations show a flying reptile called Dimorphodon and one of the
earliest birds, Archaeopteryx. What do the two animals have in common
and how are they different?
Eras of Earth’s History
The End of the Dinosaurs
Many scientists hypothesize that an asteroid hit Earth near the presentday Yucatán Peninsula, in southeastern Mexico.