Exam 4: Geologic Time: a Story in the Rocks

Dinosaurs evolved during the __________ Era.

__________ __________ refers to time measured in years.

The longer the time span that a species existed, the more precisely an index fossil can be used to determine the age of a rock.

The principle of __________ __________ states that species succeeded one another through time in a definite and recognizable order.

Volcanic eruptions eject __________ __________ into the atmosphere, a greenhouse gas that can cause warming.

Humans evolved during the __________ Era/Eon.

A/an __________ is an unconformity in which the sedimentary layers above and below the unconformity are parallel.

The principle of crosscutting relationships states that fossil organisms succeeded one another through time in a definite and recognizable order and that the relative ages of rocks can therefore be recognized from their fossils.

Precambrian refers to all the time before the start of the __________ Eon.

The earliest fossils have been found from the __________ Eon.

An unconformity in which tectonic activity tilted older sedimentary rock layers before younger sediment accumulated is:

Dinosaurs roamed the Earth during the:

Fossil remains first became very abundant during the Cambrian Period.

The volcanic gas __________ forms small particles called aerosols that reflect sunlight and cool Earth.

Imagine that you found two sandstone beds about 200 kilometers apart. The rock in one region was similar to the rock in the other, but one bed was several million years older than the other. From this information, you would conclude that:

Many scientists believe that a giant meteorite impact caused the extinction of the dinosaurs.

The principle of original horizontality is based on the fact that:

Scientists have noted that mass extinctions have coincided with:

Phanerozoic Eon sedimentary rocks contain only microscopic fossils of single-celled organisms.

Geologists establish the age relationship of rocks from different locations through the process of __________.