Bog Deposits

mineral and organic sediments, accumulating in swamps. Peat predominates among bog deposits, turning in time into “humus” fossil coal. In swamps fed not only by atmospheric moisture but also by springs of underground water, small nodules of carbonates, ferrites, phosphates, and other minerals form in the peat. Sediments of overgrown lakes can also give rise to bog deposits. Such layers of clay, sand, friable limestone, and particularly sapropel turn eventually into saprolites (boghead coal, cannel coal, and others).