Earth Through Time

How does sedimentary rock usually form?

• in large crystals

• in vertical layers

• in swirling bands

• in horizontal layers

What is the approximate age of Earth?

• 4,600 years

• 46,000 years

• 4.6 million years

• 4.6 billion years

Which sentence best describes the process of relative dating?

• Younger fossils are on top of older fossils

• Older fossils are on top of younger fossils

• Radioactive elements help determine the age of the fossil.

• Fossils are dated by comparing them with living descendants

Which definition describes absolute dating?

• finding the age of an object compared with other objects

• measuring the age of an object in years using any method

• determining the amount of a radioactive isotope in an object

• determining the age of a rock layer by studying the fossils present

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 of animals compare with animals that exist today?

• Animals in the fossil record are the same as animals that exist today.

• Animals in the fossil record are ancestors of animals that exist today

• Animals in the fossil record have no similarities to animals that exist today.

• Animals in the fossil record are more complex than animals that exist today

A geologist is studying three layers of sedimentary rock in an area. The layers have not shifted from their original positions. The geologist records the relative ages of the rocks. The bottom layer is listed as the oldest. The top layer is listed as the youngest. What did the geologist use to determine the relative ages of the rocks?

• mineral content

• radioactive decay

• the law of superposition

• the principle of unconformity

Fossils are often hardened remains of organisms that once lived, such as a bone or tooth. Which characteristic of metamorphic rock makes it unlikely for fossils to be found in this type of rock?

• Fossils are broken apart during volcanic eruptions.

• High temperature and pressure destroy the fossils.

• Tiny sediments build up in the fossils as they are deposited

• Ocean water moving across the rock carries the fossils away.

Before life evolved adaptations for living on the land, a major change took place in one of Earth’s systems. Which change made it possible for life as we know it to live on the land?

• addition of carbon to ocean water

• addition of sodium to ocean water

• addition of oxygen to the atmosphere

• addition of carbon dioxide to the atmosphere

The diagram shows several layers of rock. Which rock layer is older than layer H?

• layer F

• layer G

• layer J

• layer K

A geologist is studying a small island. He wants to know the order of historic geologic events. Which question will lead the scientist to the evidence for this study?

• Are different types of rocks found on nearby islands?

• Which types of plants and animals are most common on the island?

• How are the layers of rock on the island different from each other?

• What is the temperature of the water around the island in different seasons?