If the ratio of radioactive parent to stable daughter isotope is 1:3, how many half-lives have elapsed?

An isolated remnant of wave erosion is a ________.

Gases are called ________ gases because their concentrations are so much smaller than that of carbon dioxide.

An unconformity is a buried ________.

The _______ occurs as the tide falls.

The reflectivity of surfaces is called ________.

An isolated remnant of wave erosion is a ________.

Which one of the following is determined by the angle of repose for dry sand?

Visualize five horizontal sedimentary strata exposed in a cliff or canyon wall identified by consecutive numbers, 1 being the lowest bed and 5 being the highest. Which of the following statements concerning the strata are TRUE?

Clean, dry air is composed almost entirely of ________.