differential compaction

1. n. [Geology]
A phenomenon that occurs after the deposition of some sediments such that different parts of the sedimentary accumulation develop different degrees of porosity or settle unevenly during burial beneath successive layers of sediment. This can result from location on an uneven surface, such as near and over a reef structure, or near a growth fault, or from different susceptibility to compaction. The porosity in a formation that has experienced differential compaction can vary considerably from one area to another.