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
Funnel (ship) built to the same silhouette as the old one, in order to retain this distinctive recognition feature. A key part of the deception practiced by ships carrying out commerce raiding during both the First World War and Second World War was to disguise their ship's outline, and this included using false funnels or by changing the height or diameter of the actual funnel(s). A "mack" is a combined stack and mast, as fitted to some classes of 20th century warships. Although they can reduce top-weight, they have not gained universal popularity due to the problem of exhaust smoke fouling of