Which type of soil poses significant dangers during excavation due to its deceptive appearance?

Clay soil poses significant dangers during excavation primarily due to its deceptive nature. While it may appear stable and firm when dry, clay can become highly unstable when wet or disturbed. This characteristic makes it particularly hazardous, as it can easily collapse or shift unexpectedly during excavation activities. The compactness and cohesive properties of clay can mask underlying instability, leading workers to underestimate the risks involved.

In contrast, sandy soil is less likely to allow for the same kind of deceptive stability because it tends to drain well and has a tendency to shift more visibly. Loamy soil, which is a mix of sand, silt, and clay, is usually more stable and easier to work with. Gravel, being larger and more angular particles, typically provides good drainage and compaction, but does not have the same cohesion issues as clay.