Geologic Time: Essay Review Questions for the Test Questions on pg. 121

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Geologic Time: Essay Review Questions for the Test Questions on pg. 121 (Answers on pg. 120)
1. What are the different types of fossils that can be found in rock and explain each type.

See your notes

Petrified- turns to stone

Mold- hollow area in shape of organism

Cast- copy of shape of organism

Carbon film- thin coating of carbon

Trace Fossil- evidence of activities (footprints)

Preserved remains- remains with little or no change (ice, tar, amber)
2. How does the fossil record support the theory of evolution?

Fossils occur in a particular order. Older rocks contain fossils of simpler organisms and younger rocks contain fossils of more complex plants and animals.

3. What is the law of superposition?

The oldest rock layer is at the bottom. The youngest rock layer is at the top.

4. Compare and contrast relative and absolute ages of rocks.

Both describe the ages of rocks. The relative age of a rock is its age compared to the ages of other rocks. The absolute age of a rock is the number of years since that rock formed.

5. How were moon rocks used to determine the age of rocks?

When Earth was very young, a large object from space collided with Earth. This collision threw a large amount of material from Earth and formed the moon. Scientists have dated moon rocks to be about 4.6 billion years old, thus the age of the Earth is roughly 4.6 billion years old.

6. What method of dating did geologists first use when they developed the geologic time scale? How is the scale different today?

Scientists first developed the geologic time scale by studying rock layers and index fossils worldwide and then placing them in order of relative age. Today, radioactive dating has helped determine the absolute age.

7. How did the extinction of dinosaurs affect the evolution of mammals?

The extinction of dinosaurs created an opportunity for mammals. During the Cenozoic Era, mammals evolved adaptations that allowed them to live in many different environments – on land, in water and even in air.

8. Which organism has a better chance of leaving a fossil: a bony fish or a jelly fish? Explain.

A bony fish has a better chance because it has hard parts.

9. See pg. 117 in NB for examples

Highlight some of the differences between the Paleozoic, Mesozoic, and Cenozoic Eras.

Paleozoic – many invertebrates; jawless fish evolved (first vertebrate); plants began to grow on land; animals began to invade land

Mesozoic – age of the dinosaurs; mammals first appeared; flowering plants evolved; first birds

Cenozoic age of mammals; marine mammals evolved; grasses led to grazing mammals; series of ice ages, humans appeared

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