Which of the following is NOT thought to contribute to the motion of Earth’s tectonic plates?

The geologic structure shown below is an example of

The light-colored rock in the geothermal area in the photograph below was formed from chemical reaction of the rock with water containing __________ introduced from underlying magma.

Divergent plate boundaries coincide with what topographic feature on the Earth?

Which of the following is not a factor that prevented the early Earth from retaining much of an atmosphere prior to about 3.8 billion years ago?

Which of the following geologic time intervals is oldest?

The most recent mountain-building event in the Appalachian Mountains and the cause of the present-day topography resulted from

The image below shows a series of lagoons (light to medium green) along the southern coast of Australia that are periodically flooded by seawater.  Which of the following rocks would be most likely to form in these lagoons?

Which of the following elements in soil tends to be supplied mainly by organic matter rather than by mineral matter (regolith)? 

Which of the following ideas in Alfred Wegener’s theory of continental drift was incorrect?