Bog

Bog, an area of porous soil insufficiently drained so that it becomes more or less saturated with water. Bogs may occur at any altitude, often occupying ledges on mountain sides or depressions in upland moors where there is a high rainfall. They may consist mainly of wet sand almost destitute of vegetation (quicksands), or their depth and extent may be largely added to by the growth and decay of certain aquatic plants. A forest stream, for instance, obstructed by a tree blown down by the wind, may expand into a pool, and from the sides of this, or any other body of stagnant water, the growth of bog-moss (q.v.) or similar plants may extend until they occupy the whole area, and then by displacing the water, expand the pool, undermine surrounding trees, and convert a wide tract of forest into a treeless swamp. The peat-bogs of Ireland commonly occupy the sites of lakes, and have layers of fresh-water shell-marl below the peat-moss. The decaying vegetation in a bog produces black carbonaceous matter or peat, colours the water, and charges it with acids known as humic acids, the chemistry of which is little known. Having a great affinity for oxygen, these acids have a reducing effect upon salts of iron, converting the sulphate into sulphide, rendering the peaty water chalybeate, and so causing it on evaporation to deposit bog iron-ore (q.v.). Though it is a laborious process, bogs may be reclaimed and converted into valuable agricultural land. Draining, turning down the heathy sod to decay, and dressing with a hot mixture of four tons of lime and five cwt. of salt and then with guano, produced good crops of potatoes and oats on Chat Moss, Lancashire.