Geologic Time: Essay Review
Questions for the Test pg. 115
(Answers on 114)
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.
5.
6.
7.
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.
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.
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.
How did the extinction of dinosaurs affect the
evolution of mammals?
8.
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.
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. 113 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