The thickness of oceanic lithosphere is ________.

Continental lithosphere ________.

Which geologic event is NOT suspected as a source of major climate change and mass-extinction events?

The stream gradient of most rivers ________.

The deepest part of a curved stream channel, where the flow is fastest, is called the ________.

The lowest elevation to which a stream can downcut is the ________.

Using the Mohs hardness scale below, which of the following statements is NOT true?

Volatiles refer to substances that ________.

Most of the pushing force driving plate motion is produced ________.

Magma tends to ________.