Dating the rocks

1) The Law of Superposition helps scientists to determine what?


a)    The absolute age of rock layers

b)    The age of fossils

c)    The relative age of rock layers

d)    The super powers of rocks


2) How old do Paleontologists believe the Earth is?


a)    2015 years old

b)    3.6 billion years old

c)    4.6 billion years old

d)    4.6 million years old



3) According to the law of superposition, the oldest fossils are found 


a)    At the top of the rock layers

b)    Near the bottom of the rock layers

c)     In the middle of the rock layers

d)    Somewhat near the surface



4) What can scientists learn from the sequence of rock layers?


a)    Geologic history of that area

b)    Future geological events

c)     the number of organisms that live in the area

d)    the impact that hikers have had on an area


5) If an index fossil is found in two rock layers that are separated by an ocean, what do you know about the relationship between the two rock layers?


a)    they are about the same age

b)    they used to be in the same area

c)     the are made of the same kind of rock

d)    the rock layers are unrelated


6) Which type of dating method can be used on rock layers by applying the Law of Superposition?


a)    relative dating

b)    absolute dating

c)     radioactive dating

d)    radiometric dating


7) What 2 things make a good index fossil?


a)    Good looks and a great smile

b)    widespread and on Earth of a short time

c)     widespread and on Earth for a long time

d)    only found in Clinton  and in every rock layer


8) What happens during radioactive decay?


a)    A stable isotope of one element changes into an unstable isotope of a different element

b)    A stable isotope of one element changes into an unstable isotope of the same element

c)    An unstable isotope of one element changes into a stable isotope of a different element

d)    An unstable isotope of one element changes into a stable isotope of the same element


9) How many of the original atoms of a decaying isotope remain unchanged after three half-lives?


a)    three- halves

b)    three -uarters

c)     one -uarter

d)    one -eighth


10) The Principle of Cross-Cutting Relationships states that an igneous intrusion is 


a)    always younger than the layers it cuts across

b)    always older than the layers it cuts across

c)     the same age as the rock it melted

d)    none of the answers are correct


11) The length of time required for half of the radioactive atoms in a sample to decay is its…


a)    era

b)    age

c)    half-life

d)    eon


12) Scientists use radioactive decay to measure…


a)    absolute time

b)    half-lives

c)     time of day

 13) A rock formed with 1000 atoms of a radioactive parent element, but only 250 radioactive parent atoms today. If the half-life of the parent element is one million years, how old is the rock?


a)    250,000 years old

b)    500,000 years old

c)     1,000,000 years old

d)    2,000,000 years old


14) What element is usually used to date fossils?


a)    uranium-235

b)    carbon-14

c)     mercury-203

d)    thorium-234


15) Which element is usually used to date rocks?


a)    Carbon-14

b)    Nitrogen-12

c)     Uranium-238

d)    Oxygen-18


16) Which is not a property of the organisms that have become useful index fossils?


a)    The organisms existed for a relatively short period of time

b)    The organisms existed over a large area

c)     The organisms were abundant when they existed

d)    The organisms still exist today.


17) Which of these is the best indication of the relative age of a rock layer?

a)    The position of the layer compared to other layer

b)    The distance of the layer extend over the earth.

c)     The chemical make up of the layer.

d)    The thickness of the layer.


18) Why is the “Law of Superposition” critical to the study of fossil life forms?


a)    It state that heavier rocks are on the bottom and light rocks to the top.

b)    It specifies that each layer of rocks is a different type of mineral.

c)     It allow us to time sequence of fossils.

d)    It tells us that organism are usually replaced by more highly adaptive ones.


19) Which radioactive substance has the longest half-life?


a)    Carbon- 14

b)    Uranium- 238

c)     Rubidium-87

d)    Potassium-40


20) Which radioactive isotope would be used to determine the age of a wooly mammoth found in Pleistocene sediments?

a)    Carbon -14

b)    Uranium-238

c)     Rubidium-87

d)    Potassium-40