Earth Science Chapter 9

Conditions during the Mesozoic Era favored the survival of reptiles.

Describe the conditions on Earth during the Mesozoic Era and the effect these geologic conditions had on plant and animal life.

The Devonian period.

During which period did land plants such as ferns begin to develop?

By radio metric dating methods.

How do scientist determine the absolute ages of rock layers?

Precambrian rocks have been so severely deformed and altered by tectonic activity that the original order of rock layers is rarely identifiable.

How do you describe Precambrian rock?

4 eons: Hadean, Archean, Proterozoic, and the Phanerozoic eon.

How many eons is the geologic time broken into?

The Paleozoic Era follows Precambrian time.

List the eras of geologic time that followed Precambrian time.

Eon, Era, Period, Epoch, Age

List the following units of geologic time in order of relative length, from the longest to shortest: age, eon, period, era, epoch.

The Cenozoic Era is divided into two periods: the Tertiary Period and the Quaternary Period and into seven epochs: the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene epoch.

Name the periods and epoch into which the Cenozoic Era is divided.

Towards the bottom.

On a geologic column, where would you find the oldest rocks?

Rock layers in a geologic column are distinguished by the types of rock the layers are made of and by the kinds of fossils the layers contain.

What can scientist assume about a rock layer that matches a similar layer in a geologic column?

88% of Earth's history.

What does Precambrian time consist of?

Millions of years ago.

What does the symbol Ma stand for?

Nearly half of the valuable mineral deposits in the world occur in the rocks of Precambrian shields and they contain few fossils.

What is Precambrian rock difficult to interpret?

The age of mammals.

What is the Cenozoic Era known as?

Scientist think the evolution occurs by means of natural selection.

What is the concept of evolution?

The saurischians, "lizard-hipped" dinosaurs and the ornithischians, "bird-hipped" dinosaurs.

What were the two main dinosaur groups during the Jurassic period?

During the Permian period.

When did Pangea form?

The end of the Cretaceous period about 65 million years ago.

When did dinosaurs become extinct?

During the Mesozoic Era.

When did dinosaurs first appear?

The Carboniferous period.

When did the first amphibians appear?

Coal deposits in Pennsylvania, Ohio, and West Virginia are the fossilized remains of the forests and swamps.

Where did the coal deposits found in Pennsylvania, Ohio, and West Virginia come from?

Mass Extinction

an episode during which large numbers of species become extinct.

Geologic Column

an ordered arrangement of rock layers that is based on the relative ages of the rocks and in which the oldest rocks are at the bottom.

Shield

large areas of exposed Precambrian rocks.

Geologic Time Scale

outlines the development of Earth and of life on Earth.

Cenozoic Era

the current geologic era, which began 65.5 million years ago; also called the Age of Mammals.

Impact Hypothesis

the explanation for the extinction of the dinosaurs.

Paleozoic Era

the geologic era that followed Precambrian time and that lasted from 542 million to 251 million years ago.

Mesozoic Era

the geologic era that lasted from 251 million to 65.5 million years ago; also called the Age of Reptiles.

Precambrian Time

the interval of time in the geologic time scale from Earth's formation to the beginning of the Paleozoic era, from 4.6 billion to 542 million years ago. It contains the first three eons of Earth's history.

Evolution

the process of change by which new species develop from preexisting species over time.