Exam 8: Clocks in Rocks: Timing the Geologic Period

A radioactive element inside has been decaying for 2 million years? Given that the half-life is 500,000 years,what percent of the parent is currently left?

Nearly 60% of the world's known oil and gas reserves were formed during the

What is the youngest rock formation exposed in the Grand Canyon?

Abrupt changes in the faunal succession in the rock record represent

Which of the following time scale divisions shows a sequence from the longest to the shortest (e.g.,month,week,day,hour,etc.)?

A radioactive isotope has decayed to the point that one-eighth of the original content is left.How many half-lives have passed?

What sort of resource has sequence stratigraphy been particularly helpful in locating?

Who was the first to discover the biological origin of fossils?

The smallest time division on the geologic time scale is a(n)

Which of the following is the best statement of the principle of original horizontality?

Before the division of the geologic time scale into eons,the Hadean,Archean,and Proterozoic eons were collectively called

Unconformities are revealed by studying how surrounding layers relate to it.Which layers are the relevant ones?

The world-wide history of geologic events on Earth is called the

Which scientist first suggested the concept of isotopic dating?

During which geologic eon did the amount of oxygen in the atmosphere approach modern levels?

In sequence stratigraphy,what is a sequence?

Which of the following can change the rate of radioactive decay?

Approximately how fast do plates spread apart?

You have been tasked by an oil company to determine where the company should look for new petroleum resources in North America.In doing so,which geologic time periods should you focus on?

Radiometric dating is possible if a rock contains a measurable amount of