Answer:
The seismic-reflection method for mapping the geometry of geologic units beneath the seafloor.
Step-by-step explanation:
The seismic-reflection method is the advance method to study the subsurface of the earth . By the help of seismic waves and we can know the internal structure of the earth .
The fundamental principle of the seismic-reflection method is that seismic wave velocity depends on the density and the rigidity of the matter. The more the rigidity the more will be the velocity. That's why where there is a contrast between the density there we get a reflection and from the amount of contrast we can able to know the rock type because every rock has a different rigidity and density. Simply we can say the seismic-reflection method work with the principle of acoustic impedance,
Acoustic impedance = density * velocity .
From a drilled core section we can clearly see the rock type and lithology of the subsurface, but up to how much depth we can drill. Up to now 12km is the highest drilling depth, which is nothing the comparison to the radius of the earth. That's why the seismic refraction method is useful.
But for less depth formation we can go for the drilling, there we can get the lithology very clearly .