secondary sedimentary structure

Secondary sedimentary structures are features within sedimentary rocks that form after the initial deposition and compaction of sediment. These structures develop later, through processes such as the formation of concretions, vein fillings, and stylolites.123

Unlike primary sedimentary structures (like bedding or ripple marks) which form concurrently with deposition, or penecontemporaneous structures (like mud cracks) which form shortly after deposition due to compaction and drying, secondary structures are a result of later geological modifications. These later processes can significantly alter the rock's composition and appearance.123