Plunge pool 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 is created by the erosional forces of cascading water on the rocks at formation's base where the water impacts. The term may refer to the water occupying the depression, or the depression itself. Plunge pools are formed by the natural force of falling water, such as at a waterfall or cascade; they also result from man-made structures such as some spillway designs. Plunge pools are often very deep, generally related to the
Tullgren funnel Antonio Berlese described this method of dynamic sampling in 1905 with a hot water jacket as heat source. In 1918 Albert Tullgren described a modification, where the heating came from above by an electric bulb and the heat gradient was increased by an iron sheet drum around the soil sample. Today's extraction funnels of this type usually combine elements from both publications and thus should be referred to as Berlese-Tullgren funnel. A variation of the Berlese funnel uses naphthalene flakes or similar aromatic mothballs in place of the heat source to drive organisms downward. This method finds application in situations