Regional and interregional unconformities in late Paleozoic strata can be traced across the stable portions of cratonic shelves, the areas covered by former epicontinental seas, and onto some stable cratonic margins. These unconformities are overlain by a wide variety of transgressive sedimentary deposits. These include: (1) a sandstone-shale-limestone succession in predominantly clastic facies of Upper Mississippian and Pennsylvanian strata; (2) evaporite-brecciated limestone succession in some shallow carbonate shelves of middle Mississippian strata; (3) stacked shelf-edge carbonate buildups at basin and stable cratonic margins in Pennsylvanian and Lower Permian strata; and (4) Devonian and Lower Carboniferous "bone beds" and nodular and clastic beds at paraconformities The stratigraphic interval between the base of the Middle Devonian to the top of the Permian in central to southwestern United States has a large number of these types of unconformities; perhaps as many as 19 in Middle and Upper Devonian beds, 12 or more in Mississippian beds, 15 or 16 in Pennsylvanian beds, and 9 to 10 in Permian beds.

Similar regional and interregional unconformities are widely recognized in continental shelf and slope sediments in Mesozoic and Cenozoic strata where they are interpreted as interruptions in sedimentation caused by fluctuations in relative sea level. Because regional unconformities of this type are physically traceable features and because sediments between them are essentially time-bracketed, these unconformities are valuable tools for correlation and regional depositional analysis.

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