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Author
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Topic: Sizes of charted rock fragments
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David Burch
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posted March 20, 2004 12:43 PM
Mud, Silt, clay:
— smaller than sand
Sand:
— very fine = 0.0625 to 0.125 mm
— fine = 0.125 to 0.25 mm
— medium = 0.25 to 0.5 mm
— coarse = 0.5 to 1 mm
— very coarse = 1 to 2 mm
Stones:
— gravel = 2 to 4 mm (BBs to small marbles)
— pebble = 4 to 64 mm (small marbles to tennis balls)
— cobble = 64 to 256 mm (tennis balls to soccer balls)
— boulder = bigger than cobbles, generally rounded
"Stones":
— aggreate of gravel, pebbles, and cobbles
Shingle:
— mixture of large pebbles and cobbles, from 16 to 256 mm
For converstion to sizes of typical things:
25.4 mm = 1 inch
Details such as give above can be found in the NOAA Nautical Chart Users Manual. This is available at no charge as a pdf file from NOAA, or we offer a printed, coil-bound copy in the books section of our catalog.
See: Chart Manual online or Book catalog index.
From: Starpath, Seattle, WA
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