What scale is used to rank earthquakes based on intensity?

Clay-sized grains are transported as __________ in a river.

What event do geologists use to define the boundary between the Precambrian and Cambrian?

___________ is molten rock erupted from volcanoes.

After rejecting the hypothesis for continental drift, scientists had to develop a new hypothesis to explain the motion of the plates. What lines of evidence, or new information, did these scientists have (that Alfred Wegener did not) that helped them to develop the theory of seafloor spreading and eventually plate tectonics?

Mammals evolved before amphibians.

Match the following components to the realm, or sphere, that they belong to.

Imagine that you are an astronomer and notice that the light from a distant galaxy is shifted toward the blue end of the electromagnetic spectrum. What conclusion would you draw?

Which of the following materials can S-waves travel through?

You measure the amount of carbon-14 (the parent isotope) and nitrogen-14 (the daughter isotope) in a sample of bone and determine that 0.75 half-lives have elapsed for carbon-14. What is the age of the bone sample if carbon-14 has a half-life of 5,730 years?