Which type of soil is classified as Type A?

Type A soil is defined as cohesive soil that has a high clay content, which is characterized by its plasticity and ability to retain moisture. This type of soil provides good stability when undisturbed, making it suitable for various construction and excavation activities. The engineering properties of Type A soil allow it to withstand significant loads without collapsing, which is essential for maintaining safety standards in construction projects.

Contrasting with the other options, gravel and granular soils (like sand) are generally characterized as Type B or Type C soils due to their lower cohesion and higher permeability. Disturbed soils can vary widely in composition and may not possess the inherent properties seen in cohesive or undisturbed soils. Thus, the classification of Type A is specifically reserved for cohesive soils like clay, which are important in engineering and construction due to their stability and structural integrity.