When flowing water comes into contact with sediment, the larger particles (such as sand) are deposited first. The smaller particles (such as silt) are carried away by the water. This process is called sedimentation.
The size and shape of sediment particles also affect how they interact with each other. Sand particles are larger and more spherical than silt particles, so they do not pack together as tightly. This means that sand is more porous than silt. Sand also has a higher permeability than silt, which means that water can flow through it more easily.
The differences between silt and sand have a significant impact on the way that they are deposited and transported by water. Silt is more likely to be deposited in calm, low-energy environments, such as lakes and ponds. Sand is more likely to be deposited in high-energy environments, such as rivers and beaches.
The ability of silt and sand to be transported by water is also important for understanding the formation of sedimentary rocks. When sediment is deposited, it is eventually compacted and cemented together to form rock. The type of sedimentary rock that is formed depends on the size and shape of the sediment particles. For example, sandstone is formed from sand, while siltstone is formed from silt.
The next table summarizes the key differences between silt and sand:
| Property | Silt | Sand |
|---|---|---|
| Size | Smaller (<0.0625 mm) | Larger (0.0625-2 mm) |
| Shape | Angular | Spherical |
| Porosity | Smaller | Larger |
| Permeability | Lower | Higher |
| Depositional environment | Calm, low-energy environments | High-energy environments |
