What is Seismic stratigraphy, seismic facies?

Seismic stratigraphy is the interpretation of the stratigraphy and depositional history of a basin from the geometry of its seismic reflections. A seismic facies is a three-dimensional unit of reflections whose character (continuity, amplitude, frequency, internal geometry: parallel, divergent, sigmoid, chaotic, mounded) differs from that of its neighbours and is interpreted as a depositional environment.