Exam 8: Time and Geology

In geology, _____ usually means determining time equivalency of rock units.

When the ____ came to a close, dinosaurs became extinct.

The Earth is approximately _____ years old.

The Earth's largest mass extinction coincides with _____ in Siberia.

The relative-dating principle of __ states that fragments included in a host rock are older than the host rock.

Our ability to assign an age to geological and archaeological materials is based on our ability to measure the relative abundance of radioactive ___ and their stable decay products.

In radioactive decay a(n) _______ emission is the emission of two neutrons and two protons from a nucleus.

Isotopes of the same element have different numbers of neutrons.

_____ are subdivisions of eras.

A(n) _______ fossil is a fossil from a very short-lived, geographically widespread species that existed during a specific interval of geologic time.

______ denotes the vast amount of time that precedes the Paleozoic Era.

The _______ Era is the Age of Mammals.

So far, the oldest mineral found on Earth is approximately 4.4 billion years old.

_______ is the spontaneous nuclear change of isotopes with unstable nuclei.

The _____ includes most of geologic time (87%).

Isotopic dates from volcanic ash or lava flows layered between fossiliferous sedimentary rocks have been used to assign numerical ages to the geologic time scale.

Uniformitarianism reflects the belief among geologists that the Earth remains uniform and unchanging through time.

Isotopic dating has shown that the Precambrian took up ______% of all geologic time.

A(n) _________ is a contact in which an erosional surface on a pluton or metamorphic rock has been covered by sedimentary (or volcanic) rock.

A(n) _______ is an erosional surface that represents a gap in the geologic record.