Plunge pool softer or fractured rock has been eroded back to a knickpoint, water continues to bombard its base. Because this rock is often less resistant than overlying strata, the water from the higher elevation continues eroding downward until an equilibrium is achieved. A somewhat similar bowl-shaped feature developed by flowing water, as opposed to falling water, is known as a scour hole. These occur both naturally and as a result of bridge building. Plunge pool A plunge pool (or plunge basin or waterfall lake) is a deep depression in a stream bed at the base of a waterfall or shut-in. It
Marsh funnel damaged, and the funnel should be replaced. In some companies, and Europe in particular, the volume collected is a litre, for which the water funnel time should be 28 seconds. Marsh himself collected 0.50 litre, for which the time was 18.5 seconds. The Marsh funnel time is often referred to as the Marsh funnel viscosity, and represented by the abbreviation FV. The unit (seconds) is often omitted. Formally, the volume should also be stated. The (quart) Marsh funnel time for typical drilling muds is 34 to 50 seconds, though mud mixtures to cope with some geological conditions may have a