Shoal in rivers, streams, and lakes. A shoal–sandbar may seasonally separate a smaller body of water from the sea, such as: The term "bar" can apply to landform features spanning a considerable range in size, from a length of a few metres in a small stream to marine depositions stretching for hundreds of kilometers along a coastline, often called barrier islands. They are typically composed of sand, although they could be of any granular matter that the moving water has access to and is capable of shifting around (for example, soil, silt, gravel, cobble, shingle, or even boulders). The grain size
Silt out Silt out A silt out is a situation when underwater visibility is rapidly reduced to functional zero by disturbing fine particulate deposits on the bottom or other solid surfaces. This can happen in scuba and surface supplied diving, or in ROV and submersible operations, and is a more serious hazard for scuba diving in penetration situations where the route to the surface may be obscured. The most common cause in scuba diving is when a divers' fins are used too forcefully or in the wrong direction; disturbing silt, particularly in caves, wrecks or in still fresh water environments. Specific non-silting