Test: Earth's History

What are the different units in the Geological Time Scale?

• Paleozoic, Mesozoic & Cenozoic
• Eons, Eras, Periods & Epochs
• Atmosphere, Ocean & Continents

Hollow area in the sediment which shows the shape of an organism or a part of the organism.

• cast
• carbon film
• mold

What is the law of superposition?

• For horizontal sedimentary layers, the youngest layer is on the bottom & each higher layer is older than the layer below
• For horizontal sedimentary layers, you cannot tell the age by the position of the layer
• For horizontal sedimentary layers, the oldest layer is on the bottom & each higher layer is younger than the layer below.

Why are index fossils important?

• they tell the relative ages of rock layers in which they occur
• To discover new dinosaur fossils near the index fossil
• To help us study earthquake patterns

What is radioactive decay?

• When a rock becomes radioactive and isn't safe to be used to study absolute age
• Radio waves do not make it to their listeners and are radio channels are fuzzy
• When an element breaks down or decays

Magma that forces its way into rocks and hardens is called a(n)_____________________.

• extrusion
• fault
• unconformity
• intrusion

What is the difference between relative age and absolute age?

• relative age is compared to another rock layer, absolute age is number of years since rock layer formed
• absolute age is compared to another rock layer, relative age is number of years since rock layer formed
• relative age and absolute are the same, geologist just can't agree on which name to use

A(n) __________ is a gap in the geological record where some rock layers have reenlist due to erosion.

• element
• extrusion
• intrusion
• unconformity

____________ is lava that hardens (igneous rocks) on the surface.

• intrusions
• extrusions
• unconformity
• radioactive decay

These fossils are widely distributed and the organism existed only briefly and help geologists tell the relative ages of the rock layers in which they occur.

• trace fossil
• petrified fossil
• index fossil
• carbon film