Clastic rock The term "mud" is used when clay and silt particles are mixed in the sediment; "mudrock" is the name of the rock created with these sediments. Furthermore, particles that reach diameters between .062 and 2 millimeters fall into the category of sand. When sand is cemented together and lithified it becomes known as sandstone. Any particle that is larger than two millimeters is considered gravel. This category includes pebbles, cobbles and boulders. Like sandstone, when gravels are lithified they are considered conglomerates. Conglomerates are coarse grained rocks dominantly composed of gravel sized particles that are typically held together by a
Polish Soil Classification effect of specific groups of soil forming processes. Soil types are divided into subtypes. Geological origin of bedrock described by "rodzaj gleby" describes geological origin and properties of material from which the soil was formed. It is not the same as soil family from USDA Soil Taxonomy. Examples can be: granitoid, basalt, amphibolite, sandstone, limestone (with specified period of formation), gypsum, glacial till, sandur sand, loess and others. Sizes of soil particles and texture of soil material are very similar to USDA classification. It makes possible correlating results of particle size analysis of soils described using USDA and Polish Soil