Page 42 - Petrology of Sedimentary Rocks

there still may be a large amount of sediment finer than that. To obtain grain-size
parameters (mean, a,, etc.) the cumulative curve is extended in a straight line on

ordinary arithmetic (squared) graph paper from the last date point (usually IO+) to 144
at 100 percent. This assumed that essentially all clay particles are larger than l4Q (0.06
micron), and that the clay mode is somewhere near 124 (0.24 micron). Grain size data
may then be obtained from this extrapolated curve.

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