Which type of soil or rock is classified as Stable Rock in the soil classification system?

Stable Rock is classified as Natural solid mineral matter in the soil classification system because it represents the most consolidated form of earth material. This classification denotes rock that has undergone lithification processes, resulting in a dense, durable material that offers significant load-bearing capacity and stability for construction and excavation projects.

Understanding what constitutes stable rock is crucial for excavator operators since this type of material impacts the choice of equipment, excavation techniques, and safety measures. The other options, such as loose sand, soft clay, and silt, are considered less stable due to their granular or cohesive nature, which can shift or settle under load, leading to challenges in excavation and construction.