Exam 24: Geologic Time

Another name for cyanobacteria,the earliest evidence of ancient life,is

The Paleozoic era ended and the Mesozoic era began about ______________ million years ago.

Because sediments are not deposited continuously in a given locality over time,breaks called ______________ occur in the rock record.

The oldest known fossils of the genus Homo date from about how long ago?

The oldest evidence of life on Earth dates back to about how many years ago?

The oldest evidence of life on Earth dates back to about how many years ago?

The term Cambrian explosion refers to

Naturally occurring uranium ultimately decays to isotopes of the element named ______________.

Periods are divided into

The organisms called ______________ were the first organisms with eyes and were wiped out at the end of the Paleozoic era.

Sedimentary layer A lies above sedimentary layer B.Fault C cuts through B but does not affect A.Arrange A,B,and C in order of oldest first to youngest last.

Reasonable values for the absolute ages of sedimentary rocks are frequently determined by relating them to ______________ rocks whose absolute ages have been determined.

The Oligocene is a(n)

If a rock sample contains uranium and lead,but no lead-204 is present,then

The Great Dying occurred at the end of the ______________ era.

We live in the period called the

The Permian is a(n)

Trace fossils are

Which of the following eons is the oldest?

The study of fossils is called