A depositional sequence is defined as a relatively conformable succession of genetically related strata bounded by subaerial unconformities or their correlative conformities. The critical part of this definition is that sequences are bounded above and below by subaerial unconformities, or by correlative conformities, that is, surfaces that correlate updip to a subaerial unconformity. A subaerial unconformity is a surface formed through subaerial exposure and erosion, and includes features formed by downcutting rivers, soil processes, and karst processes.