Silt Silt can be visually observed with a hand lens, exhibiting a sparkly appearance. It also can be felt by the tongue as granular when placed on the front teeth (even when mixed with clay particles). Silt is created by a variety of physical processes capable of splitting the generally sand-sized quartz crystals of primary rocks by exploiting deficiencies in their lattice. These involve chemical weathering of rock and regolith, and a number of physical weathering processes such as frost shattering and haloclasty. The main process is abrasion through transport, including fluvial comminution, aeolian attrition and glacial grinding. It is in
Silt out which is also likely to disturb silt where it makes contact, and the underwater work may also disturb silt. For these reasons surface supplied divers must often operate in very poor visibility. Remotely operated underwater vehicles and submersibles manoeuver by using thrusters, and the water blast from thrusters has a similar effect to the wash from fins. Silt outs are dangerous situations for scuba divers, particularly in enclosed spaces or when there is no direct access to the surface (an overhead environment). Training courses in overhead environment diving, such as wreck or cave diving teaches various methods to cope with