Deformation of sediments can begin during deposition and be caused either by the depositional process itself or by other mechanisms triggered by it or by gravity. Deformational events also occur after deposition on or below the sedimentary interface. A first distinction can thus be made between syn - and post-depositional deformations, with the proviso made in the introduction, i.e., ignoring tectonic processes. In certain cases, however, it is not easy to discriminate between sedimentary and tectonic causes of sediment deformation, especially if tectonic stresses act on a still soft sediment. Some examples will be shown and discussed to make this point clear.
The following survey of deformative structures does not pretend to be systematic and exhaustive. It is rather aimed at exemplifying common and significant cases. I will start with smaller, gentler, and more localized structures and end with forms of larger scale and greater intensity. At one end of the spectrum, only parts of beds or bed surfaces are involved, at the other end can be seen deformation throughout packets of beds, sedimentary bodies and stratigraphic successions up to mountain size.
Plate 104. Desiccation cracks (mud cracks)
Plate 105. Desiccation structures: mud cracks, polygons and curls
Plate 106. Fossil desiccation cracks (molds or fills)
Plate 107. Tepee structure
Plate 108. Pitted mud surfaces
Plate 109. Injection structures: mud volcanoes
Plate 110. Injection structures: sand volcanoes
Plate 111. Injection structures: pockmark
Plate 112. Dewatering structures
Plate 113. Dewatering structures: dish
Plate 114. Dish-and-pillar structure
Plate 115. X (bow-tie) and Y-shaped dewatering structures
Plate 116. Convolute lamination
Plate 117. Some details of convolute laminae
Plate 118. Convolute and oversteepened foreset laminae
Plate 119. Current drag effects on foreset laminae
Plate 120. Current drag effects on cross-bedding
Plate 121. Deformation by impacting objects: bomb sags
Plate 122. Load deformation: section view
Plate 123. Load structures: plan view (load casts)
Plate 124. Current marks deformed by loading
Plate 125. "Squamiform" load casts (A) and load-casted ripples (B)
Plate 126. Ball-and-pillow structure (pseudonodules)
Plate 127. Enterolithic folds
Plate 128. Brecciated structure
Plate 129. Deformations related to sliding and slumping
Plate 130. Submarine slides: morphology and geometry
Plate 131. Ancient submarine slide: top unconformity
Plate 132. Folded beds in a paleoslide
Plate 133. Box-shaped folds in a sandy paleoslide
Plate 134. Rotated block in a paleoslide
Plate 135. Sedimentary and tectonic folding compared
Plate 136. Details of a paleoslide: snapped bed
Plate 137. Details of paleoslides: outcrop vs. core
Plate 138. Paleoslides: detachment scars
Plate 139. A Close-up of slide scars