: for sediment in beverages, see dregs.    sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice, and/or by the force of gravity acting on the particles. for example, silt falls out of suspension via sedimentation and forms soil (some of which may eventually become sedimentary rock). sediments are most often transported by water (fluvial processes), wind (aeolian processes) and glaciers. beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. desert sand dunes and loess are examples of aeolian transport and deposition. glacial moraine deposits and till are ice-transported sediments. == classification == sediment can be classified based on its grain size and/or its composition. ===grain size===    thumb  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" ! Ï scale !! size range(metric) !! size range(inches) !! aggregate class(wentworth) !! other names |- | &lt; -8 || &gt; 256&nbsp;mm || &gt; 10.1 in || boulder |- | -6 to -8 || 64â256&nbsp;mm || 2.5â10.1 in || cobble |- | -5 to -6 || 32â64&nbsp;mm || 1.26â2.5 in || very coarse gravel || pebble |- | -4 to -5 || 16â32&nbsp;mm || 0.63â1.26 in || coarse gravel || pebble |- | -3 to -4 || 8â16&nbsp;mm || 0.31â0.63 in || medium gravel || pebble |- | -2 to -3 || 4â8&nbsp;mm || 0.157â0.31 in || fine gravel || pebble |- | -1 to -2 || 2â4&nbsp;mm || 0.079â0.157 in || very fine gravel || granule |- | 0 to -1 || 1â2&nbsp;mm || 0.039â0.079 in || very coarse sand |- | 1 to 0 || 0.5â1&nbsp;mm || 0.020â0.039 in || coarse sand |- | 2 to 1 || 0.25â0.5&nbsp;mm || 0.010â0.020 in || medium sand |- | 3 to 2 || 125â250 Âµm || 0.0049â
Environmental_soil_science Petrology Sedimentology Sediments