19".] STEVEXSOX— FORMATION OF COAL BEDS. 35 



lateral border, both coal and sandstone split up so as to interlace. 

 The condition is precisely similar to a cake of sandstone in clay. 

 Jukes asks, if the sandstone was deposited in water, why not the 

 coal also, for they are interstratified. The partings of sand in 

 coal beds are of the same type. The laminae of coal are obviously 

 lamina of deposition ; their arrangement and their alternation with 

 films of shale or with thicker partings of clay or sand would all be 

 explained by the gradual deposition of lamin?e and strata of dif- 

 ferent kinds of substances and by different degrees of mingling at 

 the bottom of some body of water. 



3. The extreme bifurcation of some coal beds; and here are 

 phenomena extremely perplexing from the standpoint of the in 

 situ theory. The great bed near Dudley, known as the Thick coal, 

 is composed of numerous benches, each with its own persistent 

 peculiarities. At two miles north from Dudley there are eleven 

 benches, with 36 feet 6 inches of coal and 2 feet 11 inches of part- 

 ings ; while at one mile east from Dudley, there are thirteen benches 

 with 28 feet 7 inches of coal and i foot 9 inches of partings. But 

 at two miles east of north from Dudley, the upper two benches, 

 there known as the Flying Reed coal, are at 84 feet above the Thick 

 coal ; at two miles farther, the interval has increased to 204 feet, 

 while an intercalation of 10 feet appears midway in the Thick coal 

 below. The benches retain their distinctive features throughout. 

 Similar conditions prevail toward the west, where the interval be- 

 tween the Flying Reed and the other portion of the Thick coal 

 increases from almost nothing to 128 feet within barely three miles. 



There is a higher bed known as the Brooch coal. It is 95 feet 

 above the Flying Reed, where that bed is 10 feet 6 inches above the 

 Thick; but where the latter interval becomes 115 feet, the former is 

 only 30 feet. Thus, while the Brooch and Thick are rudely parallel, 

 the Flying Reed is oblicjue between them. 



The normal section persists in the central southern part of the 

 field to some distance south from Dudley ; but toward the southwest 

 the Thick coal breaks up, loses its structure and becomes worthless ; 

 toward the southeast, the bed thins out, has little good coal and is 

 troubled by " rock faults"" or "cakes of sandstone." 



35 



