Exam 4: Geologic Time Concepts and Principles

The ____ states that sediment extends laterally in all directions until it thins and pinches out, or terminates, against the edge of the depositional basin.

Nicolas Steno used a mathematical model and the rate of Earth's cooling to calculate that the age of the Earth must be 20-400 million years old.

After three half-lives, a radioactive element will have ____ of its original parent atoms.

Divisions of the geologic time scale are divided into equal increments of 250 million years.

Who developed the principle of uniformitarianism?

The two types of geologic age dates are ____________________ and ____________________.

Determining specific, quantitative dates for rock units or events expressed in years before the present is known as ____ dating.

A(n) ____________________ is a break in the geologic record resulting, at times, from erosion.

Discuss methods of absolute dating that may provide insight into relatively recent climate change. How are these methods employed?

Which scientist used a mathematical model and the rate of Earth's cooling to calculate that the age of the Earth must be 20-400 million years old?

Uranium-238 (U-238) that undergoes alpha decay becomes ____.

Discuss the historic use of relative and absolute dating to develop the geologic time scale. Were relative dates or absolute dates first employed to develop this time scale? Explain your reasoning.

Radiometric dating is based on ____.

The principle of fossil succession is one of the principles for relative-age determinations of strata and their contained fossils.

Any time an element undergoes radioactive decay, it becomes a new element.

We are currently in the Quaternary period of the Cenozoic era.

Because heat and pressure affect the ratio of radioactive parent to stable daughter, ____ rocks generally are difficult to date accurately by radiometric dating.

Radiometric dates are unaffected by metamorphism.

Tree-ring dating, or dendrochronology, is a relative dating method.

A rock sample containing an isotope with a half-life of 28 million years has an initial mass of 184 grams. How much time has elapsed after three half-lives?