The Changing Earth

Sometimes a fossil is formed as a result of the movement of an organism in soft sediment. What type of fossil is this called?

• bone fossil
• trace fossil
• frozen fossil
• petrified fossil

Imagine that you found this fossil on a mountaintop. What could you conclude from your discovery?

• This organism is now extinct.
• This trace fossil is older than the mountaintop.
• The mountaintop is made of metamorphic rock.
• The rocks on this mountaintop were once at the bottom of an ocean.

A fossil of an ancient seashell is found in the Rocky Mountains. What living organism would you expect to find in that region now?

• tropical plant
• shark
• grizzly bear
• penguin

Over millions of years, landmasses can break up and move apart. What could you do to determine if two separate areas were once part of a single landmass?

• compare the types of fossils found in the two areas
• compare the types of living things found in the two areas
• analyze the ages of trees in the two areas
• calculate the number of different fossils found in the two areas

Suppose the climate where you live is cool and dry. What could you infer about the ancient climate of your area if you found a fossil of a tropical fern?

• The area was once covered in ice.
• The area was once humid and warm.
• The area was once part of a large, single landmass.
• The area has always had a cool, dry climate.

Which of these choices is an example of the way a geologist would use relative dating?

• determining the minerals that make up rocks
• placing rock layers in order of oldest to youngest
• classifying rocks as igneous, sedimentary, or metamorphic
• using radioactive isotopes to determine the exact ages of rock samples

Which property of fossils allows scientists to determine the relative ages of rock layers?

• Fossils form from the remains of living organisms.
• Fossils are usually found only in sedimentary rock.
• Fossils show how organisms change over time.
• Fossils can be analyzed to determine their exact ages.

Fossils are the preserved remains or traces of plants and animals that have lived on Earth throughout Earth’s history. How does the fossil record change over time?

• Organisms have become less complex throughout Earth's history.
• Fossils have not changed over time.
• There are no similarities between fossils and today's organisms. 
• Organisms have become more complex throughout Earth's history.

Ammonites are an example of an index fossil. The drawing below shows fossil ammonites in a layer of sedimentary rock in between two layers of igneous rock. How can the ammonites be dated using absolute dating methods?

• radiometric dating of the igneous layers
• radiometric dating of the ammonite fossils
• radiometric dating of the sedimentary rock
• determining the half life of the ammonite fossils

Basalt is a gray or black igneous rock. Voyager uses an absolute dating method to study a sample of basalt. What will the method help her learn about the basalt sample?

• the age of the sample
• the composition of the sample
• the physical structure of the sample
• the geographic distribution of the sample