Grain size Grain size Grain size (or particle size) is the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. This is different from the crystallite size, which refers to the size of a single crystal inside a particle or grain. A single grain can be composed of several crystals. Granular material can range from very small colloidal particles, through clay, silt, sand, gravel, and cobbles, to boulders. Size ranges define limits of classes that are given names in the Wentworth scale (or Udden–Wentworth scale) used in the
Gravel Ridge, Arkansas $44,318. Males had a median income of $31,553 versus $21,903 for females. The per capita income for the CDP was $16,932. About 7.9% of families and 8.5% of the population were below the poverty line, including 10.6% of those under age 18 and 12.9% of those age 65 or over. The climate in this area is characterized by hot, humid summers and generally mild to cool winters. According to the Köppen Climate Classification system, Gravel Ridge has a humid subtropical climate, abbreviated "Cfa" on climate maps. Gravel Ridge, Arkansas Gravel Ridge is a former census-designated place (CDP) in Pulaski County,