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A shoal, sandbank, sandbar (or just bar in context), or gravelbar, is a characteristically linear landform completely within or extending into a body of water.〔(Shoal ) - Dictionar.com. Retrieved 11 October 2015.〕 It is typically composed of sand, silt, and/or small pebbles. A spit–sandspit is a type of shoal. == Description == Shoals are characteristically long and narrow (linear) and develop where a stream, river, or ocean current promotes deposition of sediment and granular material, resulting in localized shallowing (shoaling) of the water. Shoals can appear as a coastal landform in the sea, where they are classified as a type of ocean bank, or as fluvial landforms in rivers, streams, and lakes. A shoal–sandbar may seasonally separate a smaller body of water from the sea, such as: * Marine lagoons * Brackish water estuaries * Freshwater seasonal stream and river mouths and deltas. 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「shoal」の詳細全文を読む スポンサード リンク
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