1. P-waves are seismic waves. They are longitudinal waves.      2. S-waves are seismic waves. They are transverse waves.      3. Seismic waves are detected using a seismograph.      4. A shadow zone is where only P-waves are detected not S-waves.      5. The paths of P and S-waves curve as they travel through the Earth because the density of the          Earth's material increases with depth.      6. a)  P and S-waves travel faster in more dense material.          b)  P-waves travel through solids and liquids .          c)  S-waves travel through solids only.          d)  P-waves are faster than S waves.          e)  P and S-waves reveal the structure of the Earth as they travel through it.