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Three main kinds of syndepositional deformation are found in cross-bedded sand-grade .sediments. The first type is characterized by simple recumbent folds of broadly parabolic form. The second is marked by series of folds, with or without overturning. The third type is much more complex, presenting a combination of faulting, folding, and the local destruction of bedding. The type marked by recumbent folds is interpreted as due to the deformation of a liquefied for perhaps fluidized) sand by current drag following an event in the majority of cases suspected to be an earthquake shock. By reference to empirical and theoretical studies of sedimenting systems, and the behaviour under small shear stresses of liquids of high viscosity, this physical model is developed analytically to yield equations describing the geometry of the deformations in terms of the thickness of the deformed bed, the settling velocity and concentration of particles in the liquefied sand, the viscosity of the liquefied sand, and the magnitude of the deforming force. The equations describe a fold surface that is a portion of a flat-lying parabola, and show that the proposed circumstances of deformation are plausible in terms of what is known of the real situation. They further reveal that, under the assumptions made in the analysis, the vertical height of the fold hinge above the base of the bed is a function only of the initial shape of the deformed cross-stratum, the shear rate in the liquefied materials, and the falling velocity and concentration of particles in the liquefied bed. The shapes of deformations calculated from the equations agree well with patterns observed from the geological record. [ABSTRACT FROM AUTHOR]

A synthetic rubber base spray adhesive was used to obtain high-relief, rapidly drying peels of moist unconsolidated beach sand. Samples from vertical planar trench walls and box coring devices were obtained instantaneously and completely hardened in about fifteen additional minutes, with doing times dependent primarily on air temperature. This technique can also be used for preservation of sediment-core structures in the laboratory. [ABSTRACT FROM AUTHOR]

Marine, mid-Tertiary mudstones and siltstones of northwestern Oregon and western Washington contain unusual calcite pseudomorphs that commonly form the nuclei of carbonate concretions. These pseudomorphs typically have the shape of rhombic prisms, with dipyramidal terminations, that arc much elongated due to multiple twinning (?). They appear similar to the glendonite pseudomorphs of New South Wales, however, their rhombic (orthorhombic?), prismatic form is at variance with the reported monoclinic form of the glendonite pseudomorphs. Internally, the pseudomorphs consist of granular calcite that takes the form of large ovoid crystals, radial or spherulitic crystals, fibrous but non-radiating crystals, and mosaic crystals of clear spar. The original mineral, believed to be aragonite or one of the hydrated carbonates, probably formed in soft, organic-rich mud, possibly in the burrows of marine organisms. Changes in physicochemical conditions caused early solution of the original mineral, leaving hollows or molds that quickly filled by precipitation of granular calcite. Judging from the low δC13 values of the pseudomorpbs, the carbonate carbon of this granular calcite was supplied from CO2 produced through decay of local masses of organic matter. Concretionary calcite, supplied from a different source as shown by much higher δC13 values, formed around the pseudomorphs. The entire pseudomorphic and concretionary process took place only a short distance below the depositional interface, prior to compaction and lithification of the host mudstone. [ABSTRACT FROM AUTHOR]

Three orthogonal planes (two vertical and one horizontal with respect to the apparent bedding structure) of a core sample of seemingly graded graywacke sandstone have been petrographically analyzed in order to determine the form and characteristics of the lithologic gradients in the specimen. Compositional and textural properties were sampled in thin section according to an orthogonal grid pattern on each of the three faces. Variability among rows and columns (plus interaction) with respect to each petrographic variable was tested by analysis of variance using a two way classification. A larger number of properties show significant variation among the rows of the sampling grid (thus in a vertical direction) than in the horizontal plane of the apparent bedding. Quality control models with confidence limits, which display graphically trends in the individual constituents, indicate that feldspar proportion, mica proportion, and quartz grain size exhibit significant gradients (above the level of analytical error) in the direction perpendicular to the bedding. Quartz proportion oscillates in a nonsystematic fashion, and quartz grain shape shows no trend in the vertical planes of the specimen. The petrographic variability observed in the horizontal plane of the bedding is generally trendless. Partial trend surfaces show that the trends in quartz grain size are dominant, but are not simple in form according to the comparative reductions in total variation achieved by fitted surfaces of successively higher degree. Again, the major portions of variability are explained by the surfaces fitted to planes perpendicular to the bedding. The textural homogeneity of the rock in the horizontal (bedding) plane is reflected in the relatively subdued trends exposed by the surfaces in this direction. Taking grain size as an example, a 1: 1 correspondence is established between this property and the theoretical effects of settling in a liquid medium by a functional relationship; it... [ABSTRACT FROM AUTHOR]

Focuses on variety in morphology and internal structure of glauconite pellets. Morphological types of glauconite pellets; Origin of pellet types; Diagnostic characteristics of glauconite pellets.