Answer:
Deposition is a process in which matter, usually particles of sediment, rocks, or soil, is added to a surface. The particles are often deposited from a fluid, as they leave their suspension and settle on the surface. Deposition can happen through water or wind transport, or they can be transported along with other moving solids. Deposition in one place usually happens because of erosion in another place; materials are weathered, eroded, or knocked loose and then settle somewhere else. Different sediments will settle differently depending on their size and what transports them. In general, fluid speed and sediment size are the primary factors. Larger particles will settle out of flowing water at a higher rate than smaller particles.
Deposition can add material slowly over long periods of time. Stalactites and stalagmites, for instance, are formed when rainwater seeps into a cave through small cracks, dissolves small amounts of limestone on the way down, and then deposits it, either before dripping from the ceiling or on the floor as it lands. Over time, this deposition adds up into impressive subterranean structures.
Before deposition can happen, the material has to come from somewhere. When water or wind flow across the surface of rocks, soils, or any type of landform, the energy of the moving fluid will cause some amount of material to be pulled away from the surface. How much, and how big the particles are, depends on several different factors.
Speed: Fast-moving fluids pull away more materials.
Fluid composition: Flowing water usually has more energy than blowing wind, and it will make a better erosion or weathering agent.
Material composition: Some minerals are soluble in water, so they will erode faster. Water of a certain pH may erode certain materials faster.
Temperature: Water dissolves and carries heavier minerals much more effectively as its temperature increases. In very cold conditions, ice can move and carry sediments along with it.
Deposition occurs when these particles leave the fluid and attach to a new surface. This can happen through chemical action, as in the case of limestone in water, but often the particles fall out of their suspension in the fluid. There are two main factors in how far a particle will travel and what causes it to deposit:
Fluid speed,Particle size:
There are three main forces acting on an individual particle in flow. The first is the movement of the fluid that pushes it forward, the second is the buoyant force suspending the particle vertically, and the third is gravity. It might be easier to think of a particle in flow like a balloon that has been picked up by a strong wind. It will be carried along for some distance, and a balloon is very light, but if it is filled with air, it will eventually come back down.