they exhibit newtonian behavior, in contrast to flows with cohesive strength (i.e., mudflows and debris flows). The behavior of turbidity currents in subaqueous settings is strongly influenced by the concentration of the flow, as closely packed grains in high-concentration flows are more likely to undergo grain-to-grain collisions and generate dispersive pressures as a contributing sediment support mechanism, thereby keep additional grains in suspension. Thus, it is useful to distinguish between low-density and high-density turbidity currents. A powder snow avalanche is essentially a turbidity current in which air is the supporting fluid and suspends snow granules in place of sand grains. Resulting deposits Description Although the deposits of all four types of sediment support mechanisms are found in nature, pure grain flows are largely restricted to aeolian settings, whereas subaqueous environments are characterized by a spectrum of flow types with debris flows and mud flows on one end of the spectrum, and high-density and low-density turbidity currents on the other end. It is also useful in subaqueous environments to recognize transitional flows that are in between turbidity currents and mud flows. The deposits of these transitional flows are referred to by a variety of names, some of the more popular being "hybrid-event beds (HEB)", linked debrites" and "slurry beds". Powder snow avalanches and glowing avalanches (gas-charged flows of super heated volcanic ash) are examples of turbidity currents in non-marine settings. Grain flow deposits are characterized by a coarsening-upward distribution of grain sizes (inverse grading) within the bed. This results from smaller grains within the flow falling down in between larger grains during grain-to-grain collisions, and thereby depositing preferentially at the base of flow. Although present as grain avalanches in terrestrial sand dunes, grain flows are rare in other settings. However, inverse graded beds resulting from grain flow processes do make up so-called "traction carpets" in the lower intervals of some high-density turbidites. Liquefied flow deposits are characterized by de-watering features, such as dish structures, that result from upward escaping fluid within the flow. As with pure grain flows, pure liquefied flows seldom occur on their own. However, liquefied flow processes are very important as grains within turbidity currents begin to settle out and displace fluid upwards. This dish structures and related features, such de-watering pipes, are often found in turbidites. Debris flow deposits are characterized by a bimodal distribution of grain sizes, in which larger grains and/or clasts float within a