Fossil Record

Geologists use radioactive dating to..

• determine the relative ages of rock layers.

• tell the difference between molds and casts.

• tell where one soil horizon ends and the next one begins.

• determine the absolute ages of rocks.

What are the oldest fossils and why?

• B, C- because they are closest to the top

• A, B- because they are closest to the bottom

• They are all the same age- because they are all found on layer 2

• A, B- because they are found closest to the top

Which layer formed first?

• Rock Layer W
• Rock Layer X
• Rock Layer Y
• Rock Layer Z

According to the law of superposition, which layer is the youngest?

• A
• B
• C

In which kind of rock do we usually find a fossil?

• sedimentary rock

• metamorphic rock

• igneous rock

If scientists found this fossil, what could they infer?

• what fish are like today

• that this fish lacked oxygen

• that water once covered the area where this fossil was found

Which of the following could form a fossil?

• Bone
• Shell
• Seeds
• All of the above

Which of the following is true about molds and casts

• A mold forms when hard parts of an organism buried by sediments are gradually dissolved
• A mold that becomes filled in with hardened materials forms a cast
• A cast is a copy of the shape of an organism
• All of the above

Fossil formation is a frequent event.

• True

• False

In what way can scientists determine the ages of fossils?

• relative dating
• radioactive dating
• law of superposition
• All of the above