After a thin, unconfined sheet has flowed fora relatively short distance, threads of current typically develop and tiny channels called rills begin to form. Still deeper cuts in the soil, known as gullies, are created as rills enlarge(Figure 4.20). When normal farm cultivation cannot eliminate the channels, we know the rills have grown large enough to be called gullies. Although most dislodged soil particles move only a short distance during each rainfall, substantial quantities eventually leave the fields and make their way downslope to a stream. Once in the stream channel, these soil particles, which can now be called sediment, are transported downstream and eventually deposited.