Exam 24: Geologic Time

Primordial lead contains the isotope lead-______________, whereas radiogenic lead does not.

Much of our energy comes from coal that was formed from plants that lived during the ______________ period.

Trace fossils are

______________ dating is used specifically to establish the absolute age of organic remains.

The Devonian is a(n)

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.

The process of matching up rock layers in different localities by such means as index fossils is called

The first 87% of geologic time is often called

A(n) ______________ is any indication of prehistoric life preserved in rock.

A dike that intrudes a bed of sedimentary rock is ______________ than the sedimentary rock.

If a rock sample contains uranium and lead, and lead-204 is present, then

The Cretaceous is a(n)

Breaks, or gaps, in the rock record at a given locality are called

Which of the following radionuclides is used to date once-living material?

Geologic evidence places Earth's age at ______________ million years.

Which of the following radionuclides has the shortest half-life?

Petrified wood is a common type of ______________ fossil.

About how long ago was the last retreat of the glaciers from North America and Europe?

Geology's best tool for establishing absolute (numerical) geologic time is called ______________ dating.

The Pleistocene is a(n)