The gridded bathymetry viewed in 3D makes the possible low-stand terraces look unconvincing. For now I thill think they are coastal terraces formed at past glacial sea levels, but we may convince few people. These are not as clear cut as the nearby uplifted terraces, but this may be unsurprising for a couple of reasons. For the uplifted terraces, when the relative sea level falls (uplift faster than sea level rise, or actual sea level drop), the coral dies and the surface is preserved. For glacial terraces, as the sea level rises, different species of coral would keep on growing through the rise, logically, and may obscure the original surface. Also, for areas with little subsidence or slow uplift, like what we surveyed in St Marc Bay, succesive glacial sea level would re-occupy the same same terrace level, more or less, making a composite surface that might not be so well-defines.

I have seen few well-defined older low-stand erosional surfaces offshore California (last 2 million years; theer are well defined unconformities but not so clear that they were cut by waves in many locations.
Chris