Geologic Time Test Gr7

What are fossils?

• molds and casts of organisms that live today

• drawings of ancient animals and other organisms

• footprints or burrows of small animals that live today

• the preserved remains or traces of organisms that lived in the past

What has the study of fossils allowed scientists to do?

• describe past environments and the history of life

• study present ocean temperatures at different depths

• analyze the chemical composition of sedimentary rocks and minerals

• predict which organisms will become extinct in the future

The relative age of a rock is

• its age compared with the ages of other rocks

• less than the age of the fossils the rock contains

• the number of years since the rock formed

• its age based on how much carbon-14 the rock contains

The time it takes for half of the radioactive atoms in a sample of a radioactive element to decay is the element's

• relative age

• potassium-argon date

• absolute age

• half-life

Geologists use radioactive dating to

• determine the relative ages of rock layers

• tell the difference between molds and casts

• tell where one soil horizon ends and the next begins

• determine the absolute ages of rocks

During the Cambrian Explosion that began the Paleozoic Era, the many new forms of life that evolved

• lived on land

• were invertebrates that lived in the sea

• were invertebrates covered with scales or fur

• were single-celled

Earth's earliest atmosphere lacked which gas that is necessary for life as we know it to exist today?

• nitrogen

• carbon monoxide

• argon

• oxygen

Late in the Paleozoic Era, the supercontinent Pangea formed. The climate in the center of Pangea was probably a(an)

• extremely cold, polar climate

• hot, dry desert climate

• wet tropical climate

• warm, mild climate

Which answer best describes the climates of Europe and North America during the 1.8 million years of the Quaternary Period?

• hot and dry

• cool and rainy periods followed by droughts

• warm and mild

• series of ice ages followed by periods when glaciers melted

A fossil formed when minerals replace all or part of an organism is called a

• mold

• petrified fossil

• cast

• trace fossil