Basic properties of fluids, flows and sediment

In order to understand the processes that produce many of the sedimentary structures observed in sedimentary deposits, it is necessary to have a basic understanding of the physical properties and mechanics of the fluids that erode, transport and deposit sediments. Most of these processes result directly from movement of a fluid, commonly water but also air and ice (which, although not a true fluid, does exhibit some similar behavioural properties). Exceptions are sediments emplaced by the direct action of gravity on loose particles and on sediment-water mixtures, usually moving on a slope. During gravity emplacement, water may be important as