silt and clay. The mineral texture can be obfuscated by high soil organic matter, iron oxides, amorphous or short-range-order aluminosilicates, and carbonates. In order to precisely determine the amount of clay, sand and silt in a soil, it must be taken to a laboratory for analysis. A strategy known as particle size analysis (PSA) is performed, beginning with the pretreatment of the soil in order to remove all other particles such as organic matter that may interfere with the classification. Pretreatment must leave the soil as strictly sand, silt and clay particles. Pretreatment may consist of processes such as the sieving of the soil to remove larger particles, thus allowing the soil to be dispersed properly. Hydrometer tests may then be used to calculate the amounts of sand, silt and clay present. This consists of mixing the pretreated soil with water and then allowing the mixture to settle, making note of the hydrometer reading. Sand particles are the largest, and thus will settle the quickest, followed by the silt particles, and lastly the clay particles. The sections are then dried and weighed. The three sections should add up to 100% in order for the test to be considered successful. Laser diffraction analysis can also be used as alternative to the sieving and hydrometer methods. From here, the soil can be classified using a soil texture triangle, which labels the type of soil based on the percentages of each particle in the sample. Soil micromorphology in archaeology Soil micromorphology has been a recognized technique in soil science for some 50 years and experience from pedogenic and paleosol studies first permitted its use in the investigation of archaeologically buried soils. More recently, the science has expanded to encompass the characterization of all archeological soils and sediments and has been successful in providing unique cultural and paleoenvironmental information from a whole range of archaeological sites. See also Cutans References Morphology, soil