The pore spaces (known as vesicles) in pumice are a clue to how it forms. The vesicles are actually gas bubbles that were trapped in the rock during the rapid cooling of a gas-rich frothy magma. The material cools so quickly that atoms in the melt are not able to arrange themselves into a crystalline structure.Thus, pumice is an amorphous volcanic glass known as a  mineraloid .he abundant vesicles in pumice and the thin walls between them give the rock a very low specific gravity. It typically has a specific gravity of less than one, giving the rock an ability to float on water.
While an electromagnetic wave is called just a disturbance, a mechanical wave is considered a periodic disturbance. Mechanical waves are also called elastic waves as their propagation depends on the elastic properties of the medium through which the waves pass.
c. Electromagnetic waves can travel through empty space; mechanical waves can't d. Electromagnetic waves are long chains of vibrating molecules; mechanical waves aren't 7. Which of the following are electromagnetic waves? a. Water waves b. Radio waves c. Sound waves d. Seismic waves 8. What type of waves carry energy at a right angle to the direction of the energy flow? a. Compression waves b. Transverse waves c. Sound waves d. P-waves 9. How is wavelength measured? a. b. c. d. 10. What can you infer about a wave with a short wavelength? a. It has a low amplitude b.