Forest Preserve District of Cook County, Illinois
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Nature Bulletin No. 523-A   March 30, 1974
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation

For hundreds of years in Ireland, as in parts of northern Europe and Russia, the only fuel available to poor people has been Peat. From partially drained bogs they cut it in slabs that are piled and sun-dried. These smolder and glow continuously on the hearth of each cottage, never naming high but giving off steady heat and a characteristic odor.

Peat is a somewhat fibrous and spongy material consisting mostly of partially decayed vegetation which accumulated, for centuries or even thousands of years, underwater or in waterlogged places such as swamps and bogs. It represents the first step in the making of coal. During millions of years, vast beds of peat were compressed and gradually transformed into the various kinds of coal now mined from beneath the earth's surface.

There are two main types. One is "highmoor" or sphagnum peat formed from several species of sphagnum or peat moss. The great muskeg swamps in Canada are spongy treeless areas covered with sphagnum mosses and underlaid with that kind of peat. The other type, "lowmoor" peat, is derived largely from sedges, reeds cattails, pondweeds and other aquatic plants. Such vegetation, as it dies each year and is covered with stagnant water, decays very slowly due to lack of oxygen. Well preserved plant remains -- pollen, seeds, leaves, stems, roots and pieces of wood -- and animal bones, are commonly found in deep beds of lowmoor peat.

The principal uses of peat in the United States are for agricultural and landscaping purposes. Being lean in nitrogen, phosphorus and potash, it is not much good as a fertilizer but, being fibrous and spongy, has other valuable properties. Lowmoor peat can absorb and hold from 3 to 8 times their own weight of water; sphagnum peat can hold far more. When mixed with fine "tight" soils, peat improves their water-holding ability and also their physical structure -- their tilth. If manure or other fertilizer and ground limestone are added, peat makes the fertilizer more effective, soil water more available, and helps plants, notably lawn grasses, to withstand droughts. Acid peat, especially sphagnum, are used without limestone for acid-loving plants such as rhododendrons.

Being so absorbent, peat is used as litter in chicken houses and as bedding in barns where it becomes rich with manure and very valuable for farmland. Another use is as a conditioner to keep commercial fertilizers from drying out and becoming sticky or caked. Sphagnum moss is used extensively in greenhouses, gardens and nurseries for the propagation, growing and shipping of plants. Muck soils -- in which peat has become highly decomposed and usually mixed with alluvial deposits of mineral soil -- are extensively cultivated to grow onions, potatoes, celery, mint, and other crops.

There are extensive deposits of peat in Malaya, Australia and parts of Africa. The great Dismal Swamp in Virginia and North Carolina is a peat bog. Largely, however, they are found in northern glaciated regions where the most undrained or poorly drained depressions occur. The USSR (Russia) has by far the greatest total area of peat, followed by Finland, Canada, Sweden, the United States, Germany, Great Britain, Ireland and Norway. About half of the U.S. deposits are in northern Minnesota; most of the remainder are in Wisconsin, Michigan and Florida.

In Cook County, peat deposits lie beneath McGinnis and other sloughs in the Palos region, The largest are in the Skokie and Sag valleys where, from time to time, dangerous peat fires have burned and smoldered for months.

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