Sub-bottom profiling systems identify and measure various marine sediment layers that exist below the sediment/water interface.
A sound source emits an acoustic signal vertically downwards into the water and a receiver monitors the return signal that has been reflected off the seafloor. Some of the acoustic signal will penetrate the seabed and be reflected when it encounters a boundary between two layers that have different acoustic impedance.
Marine geological profiling allows us to detect and to map interfaces between the various sedimentary layers or the overburden / bedrock interface beneath a body of water. The technique is based on the principles of seismic reflection.