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Petroleum Geological Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
Ripple marks represent a sedimentary structure. The ripple marks are formed by the blowing wind and flowing water. Ripples are produced by the action of the fluid current and waves on the surface sand sediments. Sand ripples appear after water recedes in coastal areas. In a desert, the blowing wind produces big ripples known as dunes. Coastal and desert environmental conditions differ considerably. The humid coastal conditions differ from the dry desert sand, which affects the ripple formation in the two locations. Two kinds of ripple marks are known as follows: ‘Symmetrical ripples’ are generated by the to-and-fro motion of the blowing wind or flowing water waves often witnessed in the desert and at beaches. The to-and-fro of the water waves creates perpendicular ripple marks with sharp crests and rounded troughs. There are three different types of symmetrical ripple marks; the first is continuous ripple series, the second is overlapping ripples and the third is discontinuous ripples.‘Asymmetrical ripples’ are formed by flowing water or blowing wind in one direction. They are found on riversides or in the desert. The asymmetric patterns lead to a determination of the direction of water and wind current at the time of ripple formation.
Sedimentary Rocks
Published in F.G.H. Blyth, M. H. de Freitas, A Geology for Engineers, 2017
F.G.H. Blyth, M. H. de Freitas
Structures such as current-bedding and ripple-marks (Fig. 2.1) may be preserved in the resulting sandy and silty rocks. Shales are formed from muds deposited in somewhat deeper and less turbulent water at a distance from the shore. Limestone-forming materials derived from calcareous skeletal remains (e.g. shell debris, crinoids, algae) are often associated with such sands and muds. A sequence of fossiliferous layers may thus be formed in a marine area; they cover the older rocks that underlie the area of deposition (e.g. Fig. 2.2). Because of its content of fossil shells and shell fragments such a series may be referred to as a shelly facies. Shelf sea deposits are frequently of relatively small thickness (hundreds of metres rather than thousands); but if subsidence has affected the area during the deposition of the sediments, a greater thickness of shallow-water deposits can be accumulated. In these conditions successive pebbly layers on the foreshore come to lie farther and farther inland from the original coast, the foreshore migrating inland as the water slowly deepens over the area of sedimentation.
Paleocurrent and paleowind direction reconstruction research progress and perspectives: a review
Published in Australian Journal of Earth Sciences, 2023
F. Y. Zhao, C. L. Hu, C. C. Han, Y. Q. Dong, Q. X. Yuan
Ripple marks are a wavy bedding plane structure formed by the movement of water or waves on the sediment surface, and are the most common and prominent signs reflecting the paleocurrent direction (Wu et al., 2014). According to symmetry, ripple marks can be divided into asymmetric ripple marks and symmetric ripple marks (Figure 4). The inclination of the steep surface of asymmetric ripple marks indicates the current direction (Figure 4a), while symmetrical ripple marks indicate the wave transmission direction (Figure 4b). The current direction or wave transmission direction is perpendicular to the trend of the wave ridge (Wu et al., 2014).