When this vibration reaches an ear, it is translated into what we recognize as a sound. Sound vibration must travel through matter. This is typically air. When you say, Hello, to a friend, the air parts (called molecules) vibrate in small waves which travel to the friend and they hear the word Hello..
Continental crust is actually much thicker than oceanic crust. This is because Continental crust has been formed over a much longer period of time, and especially so due to sea-floor spreading (as new crust is constantly produced).
The continental crust is made mostly of rocks with a composition similar to granite (a light-colored rock you would expect to find in the Sierra Nevada), whereas the oceanic crust is made mostly of rocks with a composition of basalt (a dark-colored rock, like the rocks that make up the Hawaiian volcanoes).ecause continental crust is less dense than oceanic crust it floats higher on the mantle, just like a piece of Styrofoam floats higher on water than a piece of wood does. The mantle, oceanic crust and continental crust have different densities because they are made of different kinds of rock with different densities.