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
Ardleigh Gravel Pit north-east borders of a water filled pit. A footpath between Slough Lane and Park Farm runs along its north-east boundary. East of the main site is a small linear feature which as been filled in. It is on private land with no public access. Ardleigh Gravel Pit Ardleigh Gravel Pit is a 1.2 hectare geological Site of Special Scientific Interest south of Ardleigh in Essex. It is a Geological Conservation Review site. The site exposes a succession of Pleistocene levels, with an interglacial between two glacial periods. The interglacial may date back 700,000 years. The site has plant microfossils rare