Editing Sediment (section)

===Grain size===
{{main|Particle size (grain size)}}
{{see also|soil texture|Unified Soil Classification System}}

Sediment size is measured on a log base 2 scale, called the "Phi" scale, which classifies particles by size from "colloid" to "boulder".

{| class="wikitable"
|-
! φ scale !! Size range<br>(metric) !! Size range<br>(inches) !! Aggregate class<br>(Wentworth) !! Other names
|-
| < −8 || &gt; 256&nbsp;mm || > 10.1 in || [[Boulder]]
|-
| −6 to −8 || 64–256&nbsp;mm || 2.5–10.1 in || [[Cobble (geology)|Cobble]]
|-
| −5 to −6 || 32–64&nbsp;mm || 1.26–2.5 in || Very coarse [[gravel]] || [[Pebble]]
|-
| −4 to −5 || 16–32&nbsp;mm || 0.63–1.26 in || Coarse gravel || Pebble
|-
| −3 to −4 || 8–16&nbsp;mm || 0.31–0.63 in || Medium gravel || Pebble
|-
| −2 to −3 || 4–8&nbsp;mm || 0.157–0.31 in || Fine gravel || Pebble
|-
| −1 to −2 || 2–4&nbsp;mm || 0.079–0.157 in || Very fine gravel || [[Granule (geology)|Granule]]
|-
| 0 to −1 || 1–2&nbsp;mm || 0.039–0.079 in || Very coarse [[sand]]
|-
| 1 to 0 || 0.5–1&nbsp;mm || 0.020–0.039 in || Coarse sand
|-
| 2 to 1 || 0.25–0.5&nbsp;mm || 0.010–0.020 in || Medium sand
|-
| 3 to 2 || 125–250 [[micrometre|μm]] || 0.0049–0.010 in || Fine sand
|-
| 4 to 3 || 62.5–125&nbsp;μm || 0.0025–0.0049 in || Very fine sand
|-
| 8 to 4 || 3.9–62.5&nbsp;μm || 0.00015–0.0025 in || [[Silt]] || [[Mud]]
|-
| > 8 || < 3.9&nbsp;μm || < 0.00015 in || [[Clay]] || Mud
|-
| > 10 || < 1&nbsp;μm || < 0.000039 in || [[Colloid]] || Mud
|}