Name: _______________________ Date: 1/28/11 Period: _____ Page #: ____
The review sheet is due on Wednesday, February 2nd
The quiz is on Friday, February 4th
Use chapter 4 of the Earth’s Changing Surface textbook
Section 1: Fossils (Pages 106-117)
1. What is a fossil? How do fossils form?
Fossil: The preserved remains or traces of living things.
They form when living organisms die and are buried by sediment. The
sediments slowly harden into rock and preserve the shapes of the
organism. They can also form in ice, amber, or tar.
2. What type of rock are fossils most likely to be found in and why?
Sedimentary: Most organisms once lived in or near water where
sediment built up. OR The heat from igneous and metamorphic
(pressure, too) will destroy the fossil.
3. List the SIX types of fossils.
1. Petrified
2. Mold
3. Cast
5. Trace
6. Preserved Remains
4. Carbon Films
4. Reproduce the drawing on page 107, figure 2 below. (Add color!)
5. How do petrified fossils form? Give a common example.
Sediment covers the wood. Water rich in minerals seeps into the
spaces in the plant’s cells. The water evaporates and leaves behind the
hardened minerals. Common example: Wood.
6. Explain what molds and casts are and how they form.
Mold: Hollow area in sediment in the shape of an organism.
It forms when the hard parts of an organism are covered in sediment.
Cast: 3-D copy of the shape of the organism.
It forms when a mold is filled with minerals/sediment.
7. What is the difference between a mold and a cast?
A mold is hollow, but a cast is a 3-D copy of the organism.
Name: _______________________ Date: 1/28/11 Period: _____ Page #: ____
8. What is a carbon film fossil?
A thin coating of carbon on a rock. Remember that all living organisms
contain carbon.
9. What are trace fossils?
They provide evidence of the activities of ancient organisms.
10. What are the three preserved remains substances your book describes?
ICE
AMBER
TAR
11. Why are preserved remains unique? What do they fossilize that other
fossils do not?
They preserve the entire organism with little to no change.
12. How does the fossil record support the theory of evolution?
It shows how different groups have changed over time.
Section 2: Finding the Relative Age of Rocks (Pages 113-117)
1. Describe relative and absolute age.
Relative: The age of a rock compared to other rocks.
Absolute: The number of years since the rock formed.
2. What is the law of superposition?
In horizontal sedimentary rock layers, the oldest layer is at the bottom.
Each higher layer is younger than the one below it.
3. Describe extrusions and intrusions.
Extrusions: Lava that hardens on the surface.
Intrusions: Magma that cools and hardens.
4. The rock layers BELOW an extrusion are always older than it.
5. An intrusion is always YOUNGER than the rock layers around or beneath
it.
Name: _______________________ Date: 1/28/11 Period: _____ Page #: ____
6. What is a fault? How does its age compare to the rocks it cuts through?
A fault is a break in the Earth’s crust.
A fault is always younger than the rock it cuts through.
7. What is an unconformity and what causes it.
It is a gap in the geologic record caused by erosion.
8. Define index fossil and explain why they are useful.
An index fossil is a widely distributed fossil that represents an organism
that only existed for a short period of time.
They can be used to tell the relative ages of the rocks in which they
occur.
9. Label the rock layers below from youngest to oldest.
Youngest: B, A, D, E, C
Section 3: Radioactive Dating (Pages 119-122)
1. Define atom and element.
Atom: the smallest particle of an element
Element: A type of matter in which all the atoms are the same.
2. What causes radioactive decay and what happens during it?
Radioactive decay is caused by unstable elements that breakdown or
decay by releasing particles and energy.
During radioactive decay, the atoms of one element break down to form
the atoms of another element.
3. The rate of decay of each radioactive element is CONSTANT - it never
changes.
Name: _______________________ Date: 1/28/11 Period: _____ Page #: ____
4. Define half-life.
The time it takes for half of the radioactive atoms to decay.
5. What is the purpose of radioactive dating?
Determine a rock’s absolute age.
6. What are the two types of radioactive dating listed in your book, and what
types of specimens can they date?
Potassium-Argon: Dates ancient Rocks
Carbon-14: Dates once living organisms
7. What type of rock is radioactive dating usually only used for and why?
Igneous: Radioactive elements occur naturally in igneous rock.
If a geologist tried to date a sedimentary rock, they would be dating
the sediments, not the whole rock.
Section 4: The Geologic Time Scale (pages 123-125)
1. After Precambrian time, the basic units on the geologic time scale are
ERAS, PERIODS, AND EPOCHS.
2. The time between Precambrian Time and today is divided into three
ERAS. What are their names?
PALEOZOIC, MESOZOIC, AND CENOZOIC
Section 5: Earth’s History (pages 128-140)
1. How long ago did Earth form? 4.6 BILLION YRS.
2. What is a mass extinction?
Many living things become extinct at one time.
3. What is Pangaea? When did it form?
Super continent or giant landmass. It formed 260 million years ago.