Which of the following is NOT a common layer of soil in construction?

In construction, soil layers are typically classified based on their composition and characteristics, which influence their suitability for various construction purposes. Clay, silt, and sand are all recognized types of soil that commonly occur in various layers and are frequently encountered in construction practices.

Clay is a fine-grained natural soil material that becomes plastic when wet and hardens upon drying, making it significant for its construction properties. Silt consists of smaller particles than sand but larger than clay, and it contributes to the moisture retention and stability of soil. Sand, which consists of granular particles, plays a critical role in ensuring proper drainage and stability in construction applications.

Granite, on the other hand, is an igneous rock and not a soil type. While it can be found in the geological strata beneath the soil and may occasionally be encountered during excavation, it does not compose a soil layer. Instead, granite is classified as a bedrock or a solid form of mineral material, rather than a granular soil component used for layering in construction projects. This distinction highlights why granite is identified as the option that is not a common layer of soil in construction.