Coal layers often hold both gas and oil. [1] The coal layers alternate with shale, stone, and conglomerate. [2] In some parts of North America and Europe the coal-bearing strata are 18,000 feet in thickness. [3] Coal is the water-preserved and pressure-modified remains of the rank vegetation growing in the bogs and on the swamp shores of this faraway age. [4]
In many regions the glacial deposit of local ice formations may be found even among some of the upper and later coal deposits. [5] Carboniferous was the era of coal. [6]
200 millions years ago the really active stages of the Carboniferous period began. For twenty million years prior to this time the earlier coal deposits were being laid down. [7]
See also: UB 59:5; UB 60:2.7; UB 60:3.9; UB 61:2.3.