Which type of rock is NOT characterized by high bearing capacity?

Siltstone is the type of rock that is not characterized by high bearing capacity. This is primarily due to its composition and formation process. Siltstone is formed from fine-grained sediment, primarily silt, which tends to be less cohesive than the materials found in other types of rock like granite, slate, or shale. The particles in siltstone are smaller and typically do not interlock as effectively as the coarser materials, resulting in a lower overall strength and load-bearing capability. Additionally, siltstone can be susceptible to moisture, which may further weaken its structure under load.

On the other hand, granite is an igneous rock composed of a high percentage of quartz and feldspar, giving it an extremely high strength and durability, making it an excellent choice for foundations and load-bearing applications. Slate is a metamorphic rock that originates from shale and has a fine-grained texture, characterized by good durability and strength due to its transformation under heat and pressure. Shale, while not as strong as granite or slate, is still more competent than siltstone due to its layered structure and overall density.

Therefore, when assessing materials for foundation purposes or load-bearing applications, siltstone would not be a preferred choice compared to