Scouring, in geologic terms, is concentrated erosive action, especially by high-energy stream water, often at a bend in a waterway. Similar phenomena occur on beaches and the ocean ﬂoor, as a result of strong tides and tidal currents. Such scouring may result in scour ﬂats, scour ways, scour ﬂutes, and scour holes, the latter of which is a relatively deep depression in mud or sand. However, scour holes also occur in bedrock as a result of rock particles entrained in swirling water that erode in a ballmill action. Many New England streams exhibit such a feature, at times also called potholes.