For example, windblown and surf zone sands are well-rounded, while glacial sands and turbidity current deposits are angular.
Particle roundness or angularity also reflects mineralogy (soft minerals are abraded more readily than hard minerals), clast size (coarse particles become rounded more rapidly than do fine ones), and transport distance (sands become more abraded and hence rounder as the distance traveled increases).
After the grain-size distribution for a given sediment or sedimentary rock has been determined by sieving, microscopic analysis, or use of a settling tube, it can be characterized using standard statistical measures in either of two ways: (1) visual inspection of various types of graphs that plot overall percent abundance versus grain-size diameter (e.g., histograms or bar diagrams, size frequency and cumulative size frequency curves, and probability curves that compare the actual grain-size distribution to a normal straight-line Gaussian distribution) or (2) arithmetic calculations made using diameter values in either millimetres or phi units that are read off the graphic plots and inserted into standard formulas.
For siliciclastic sedimentary rocks, the following standard statistical measures are conventionally described for grain-size distributions: (1) kurtosis (peakedness) of a grain-size distribution, which compares sorting in the central portion of the population with that in the tails.
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Particle size is an important textural parameter of clastic rocks because it supplies information on the conditions of transportation, sorting, and deposition of the sediment and provides some clues to the history of events that occurred at the depositional site prior to final induration.This time around, though, she explained she's reluctant to reveal the dirty details, because it comes up in a very different set of circumstances.She said in her new book that it's already awkward that she can't join in with her buddies when they get to complaining about their terrible marriages.The grain-size distribution of sediments in many settings commonly appears to be inherited or to exhibit as much variation within a single environment as between different ones.roundness, and surface texture.Particle form is the overall shape of particles, typically defined in terms of the relative lengths of the longest, shortest, and intermediate axes.