Describe the internal and the external structure of the earth

The interior structure of the Earth is layered in spherical shells, like an onion. These layers can be defined by their chemical and their rheological properties.

Earth has an outer silicate solid crust, a highly viscous mantle, a liquid outer core that is much less viscous than the mantle, and a solid inner core.

Sonar is an application of the doppler effect used by submarines.  this test was on k12.