Graded bedding (Bailey, 1930) characterizes a clastic sedimentary deposit if there is a progressive upward change in the mean, maximum, or modal grain size. If the particle-size variation is repetitive rather than progressive, then the deposit is stratified (>1 cm scale) or laminated (<1 cm scale), but not necessarily graded. Stratified or laminated beds may also be graded if the average particle size changes progressively upward at a scale exceeding that of single laminae; this is the case in graded turbidites containing Bouma sequences. Graded beds range in thickness from ∼1 cm to many meters. The thickest graded beds are so-called “megaturbidites” which may be thicker than 100 m (Labaume et al., 1985). Thick graded beds may be composed of gravel and sand or predominantly mud (Weaver and Rothwell, 1987). The term “grading” should not be used to describe gradual changes in rock type across-bedding planes. Instead, it is better in such cases to refer to gradational bed contacts.
Graded...
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Bibliography
Allen, J.R.L., 1984. Sedimentary Structures: Their Character and Physical Basis, Volume II. Amsterdam: Elsevier.
Bailey, E.B., 1930. New light on sedimentation and tectonics. Geological Magazine, 67: 77–92.
Bagnold, R.A., 1956. The flow of cohesionless grains in fluids. Philosophical Transactions of the Royal Society of London (A), 249: 235–97.
Cas, R.A.F., and Wright, J.V., 1987. Volcanic Successions: Modern and Ancient: A Geological Approach to Processes, Products and Successions. London: Unwin-Hyman.
Hiscott, R.N., 1994. Loss of capacity, not competence, as the fundamental process governing deposition from turbidity currents. Journal of Sedimentary Research, A64: 209–214.
Kneller, B., 1995. Beyond the turbidite paradigm: physical models for deposition of turbidites and their implications for reservoir prediction. In Hartley, A.J., and Prosser, D.J. (eds.), Characterization of Deep Marine Clastic Systems. Oxford: Geological Society (London), Special Publication, 94, pp. 31–50.
Labaume, P., Mutti, E., and Seguret, M., 1985. Megaturbidites: a depositional model from the eocene of the SW-Pyrenean foreland basin, Spain. Geo-Marine Letters, 7: 91–101.
Middleton, G.V., 1967. Experiments on density and turbidity currents: III. deposition of sediment. Canadian Journal of Earth Sciences, 4: 475–505.
Nichols, G., 1999. Sedimentology and Stratigraphy. Oxford: Blackwell Scientific.
Walker, R.G., 1965. The origin and significance of the internal sedimentary structures of turbidites. Yorkshire Geological Society, Proceedings, 35: 1–32.
Walker, R.G., 1975. Generalized facies model for resedimented conglomerates of turbidite association. Geological Society of America, Bulletin, 86: 737–748.
Weaver, P.P.E., and Rothwell, R.G., 1987. Sedimentation on the madeira abyssal plain over the last 300 000 years. In Weaver, P.P.E., and Thomson, J. (eds), Geology and Geochemistry of Abyssal Plains. Oxford: Geological Society (London), Special Publication, 31, pp. 71–86.
White, J.D.L., Manville, V., Wilson, C.J.N., Houghton, B.F., Riggs, N., and Ort, M., 2001. Settling and deposition of 181 A.D. taupo pumice in lacustrine and associated environments. In White, J.D.L., and Riggs, N.R. (eds.), Volcaniclastic Sedimentation in Lacustrine Settings. Oxford: International Association of Sedimentologists, Special Publication, 30, pp. 141–150.
Cross-references
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1978 Dowden, Hutchinson & Ross, Inc.
About this entry
Cite this entry
Hiscott, R.N. (1978). Grading, graded bedding. In: Middleton, G.V., Church, M.J., Coniglio, M., Hardie, L.A., Longstaffe, F.J. (eds) Encyclopedia of Sediments and Sedimentary Rocks. Encyclopedia of Earth Sciences Series. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-3609-5_101
Download citation
DOI: https://doi.org/10.1007/978-1-4020-3609-5_101
Published:
Publisher Name: Springer, Dordrecht
Print ISBN: 978-1-4020-0872-6
Online ISBN: 978-1-4020-3609-5
eBook Packages: Springer Book Archive