What system is used to classify soil types?

The Unified Soil Classification System (USCS) is the correct method used to classify soil types based on their physical and engineering properties. This system categorizes soils based on grain size, plasticity, and moisture content, allowing engineers and builders to assess soil suitability for construction or other uses.

USCS divides soils into categories such as coarse-grained soils (gravel and sand) and fine-grained soils (silt and clay), and further classifies them with additional designations to provide a clear understanding of their characteristics. This classification helps in determining the appropriate construction techniques and foundation designs necessary for various types of buildings, enabling safe and effective construction practices.

Other systems mentioned, such as the Soil and Water Assessment Tool and the Soil Conservation Service, focus more on environmental impacts or conservation practices rather than direct soil classification for engineering purposes. The Geotechnical Classification System, while related to soil properties and used by geotechnical engineers, does not provide the same standardized nomenclature or broad applicability as the USCS. Therefore, the Unified Soil Classification System stands out as the primary method for soil classification in construction and engineering contexts.