Exam 24: Geologic Time

The study of fossils is called ______________.

Potassium-40, one of the six major radionuclides used for radiometric dating, decays to

The periods of the Cenozoic era are divided into time units called ______________.

The Jurassic period is part of the ______________ era.

The Cenozoic is a(n)

The Paleozoic is a(n)

The study of fossils is called

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

The Paleozoic era ended with an event called the

Which occurrence is associated with the demise of the dinosaurs?

We live in the period called the

The smallest units of geologic time are the

Eras are divided first into

Geologists think that Earth is how old?

A fossil imprint made by the movement of an animal is called a(n) ______________ fossil.

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

Sedimentary layer A is found above sedimentary layer B, and the two are separated by a horizontal layer of ash, C. Therefore, the order from oldest to youngest is

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

Eons are subdivided first into ______________.

Which of the following is a period of the Cenozoic era?