Earth Geologic History

Relative dating of rock layers tells us that the deeper we dig, _______.

• the younger the rocks get
• the smellier the rocks get
• the harder the rocks get
• the older the rocks get

The Law of Superposition helps scientists to determine what?

• The absolute age of rock layers
• The age of fossils
• The relative age of rock layers
• the super powers of rocks

What type of rock do fossils form in?

• Igneous
• Sedimentary
• Metamorphic
• Classic

Most events on the geologic timeline happened:

• a long time ago, near the beginning
• more recently, near the modern time
• evenly spread out
• right in the center of the timeline

_{Which rock layer in the diagram seems to be the oldest?}

• F
• E
• B
• A

_{What can scientists learn from the sequence of rock layers?}

• Geologic history of that area
• Future geological events
• the number of organisms that live in the area
• the impact that hikers have had on an area.

Radiometric dating is often referred to as 

• total age.
• absolute age.
• historic age.
• geologic age.

A rock formed with 500 atoms of a radioactive parent element, but only contains 125 radioactive parent atoms today.  If the half-life is 1000 years, how old is the rock?

• 2000 years
• 500 years
• 250 years
• 125 years

the time it takes for half the atoms in an element to decay into something else is called

• absolute age dating
• relative age dating
• half-life
• extinct

Why is the fossil record incomplete?

• fossils get eroded away over time
• most organisms never became fossils
• scavengers and decomposers eat them too quickly
• all of the above