Scientific Investigations Report 2008–5093
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2008–5093
Table 3. Particle-size classification.
[Particle-size classification modified from Buffington and Montgomery (1999) and Folk (1980). Symbol: φ, phi scale where φ = -log2 (diameter in mm); Abbreviation: mm, millimeter]
| Diameter of particle | Classification name | ||
|---|---|---|---|
| φ | mm | ||
| -8 | 256 | ||
| Coarse cobble | |||
| -7 | 128 | ||
| Fine cobble | |||
| -6 | 64 | ||
| Very coarse gravel | |||
| -5 | 32 | ||
| Coarse gravel | |||
| -4 | 16 | ||
| Medium gravel | |||
| -3 | 8 | ||
| Fine gravel | |||
| -2 | 4 | ||
| Very fine gravel | |||
| -1 | 2 | ||
| Very coarse sand | |||
| 0 | 1 | ||
| Coarse sand | |||
| 1 | .5 | ||
| Medium sand | |||
| 2 | .25 | ||
| Fine sand | |||
| 3 | .125 | ||
| Very fine sand | |||
| 4 | .0625 | ||
| Coarse silt | |||
| 5 | .0310 | ||
| Medium silt | |||
| 6 | .0165 | ||
| Fine silt | |||
| 7 | .0076 | ||
U.S. Department of the Interior | U.S. Geological Survey
URL: http://pubs.usgs.gov/sir/2008/5093
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