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Ponds. A pond is a body of water smaller than a lake. However the difference between a pond and a lake is subjective. Pond usually describes small bodies of water, generally smaller than one would require a boat to cross. Another definition is that a pond is a body of water where even its deepest areas are reached by sunlight or where a human can walk across the entire body of water without being underneath. In some dialects of English, pond normally refers to small artificially created bodies of water. Though not generally accepted, some regions of the United States define a pond as a body of water with a surface area of less than 10 acres (40,000 m²). In areas which were covered by glaciers in the past, some ponds were created when the glaciers retreated. These ponds are knowns as kettle ponds . Walden Pond in Concord, Massachuseets is a well known example. Kettle ponds are usually quite deep and clean because they are fed by underground aquifers rather than streams. Another suggested difference between ponds and lakes is that lakes are fed by rivers, creeks, and/or springs, while ponds are usually the result of rain runoff, modest springs, or perhaps a very small stream. Also, lakes tend to have much more irregular shorelines, with coves and so forth, while ponds tend to allow one to take them all in visually from a single location. Or, if the lake does have regular shorelines, then it tends to at the same time be a substantial body of water (e.g., Lake Okechobee). Lastly, while ponds may allow water to escape via some fairly modest route, lakes that allow such escape usually make use of more substantial means (creeks, rivers, etc.). Typically, a pond has no surface outflow draining off water and ponds are often spring-fed. Hence, due to the closed environment of ponds, such small bodies of water normally developed self contained eco-systems. Ponds in heavily vegetated areas also display the formation of "scum", which is a common term for dead and decaying vegetation condensing on the water skin of the pond. A contributor to this is the presence of algae, which multiplies quickly in a nutrient-rich pond exposed to strong daylight. Decaying flora provide significant amounts of such nutrients. In medieval times in Europe, it was typical for many monasteries, castles, etc. (small, partly self-sufficient communities) to have fish ponds. These are still common in the East Asia (notably Japan), where koi carp may be kept. The term is also used for temporary accumulation of water from runoff (ponded water). There are various regional names for naturally occurring ponds, e.g. in Scotland, one of the terms is lochan. The word "pond" is sometimes also used to refer to the Atlantic Ocean in the expression "across the pond" (a deliberate idiomatic understatement).
PADI 5 Star National Geographic Instructor Development Center. 198/12 Rat-U-Thit Road, Patong, Phuket, Thailand. Phone: (+66) 076292052 Fax: (+66) 076293034
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