Answer:
Subsidence is so slow that there seems to have been no depression of the upper surface of the lithosphere, so depositional environments are mostly the
same as those in surrounding areas; the succession is just thicker. These
successions are also more complete, however—there are fewer and smaller
diastems—so at times the basin must have remained under water while surrounding areas were emergent. (A diastem is a brief interruption in
sedimentation, with little or no erosion before sedimentation resumes.)
Size, shape: rounded, equidimensional, hundreds of kilometers across
Sediment fill: shallow-water cratonal sediments (carbonates, shales, sandstones),
thicker and more complete than in adjacent areas of the craton but still
relatively thin, hundreds of meters.
Hopefully that helps!
