Earth's magnetic field is not stable; throughout geologic time it ...

[torybrooks]

Earth's magnetic field is not stable; throughout geologic time it has changed direction. This change is attributed to
 
  A) changes in the direction of fluid flow in the molten outer core of Earth.
  B) magnetic pole reversals.
  C) fluctuations in the time / space continuum.
  D) changes in the direction of fluid flow in the molten inner core of Earth.

Question 2

Body waves can be divided into two typesprimary waves and secondary waves. What is the difference between these two types of body waves?
 
  What will be an ideal response?

[aadams68]

Answer to Question 1

Answer: A

Answer to Question 2

Answer: Primary waves, as their name suggests, are the first to register on a seismograph. P-waves are fast, longitudinal waves that move out in all directions from their source. Because both solids and liquids respond to compressional/expansional movement, P-waves can travel through any type of material. Secondary waves are slower than P-waves; as such they are the second to register on a seismograph. S-waves are transverse; they vibrate in an up-down, side-to-side fashion. Because liquids cannot support this type of movement, S-waves cannot travel through liquids.

[torybrooks]

Excellent

[abro1885]

Gracias!