62 STEVENSON— FORMATION OF COAL BEDS. [April i8, 



feet. The variation in position is in the lower or first bed, the 

 place of the third remaining apparently unchanged. The third and 

 fourth, on the contrary, converge toward the east and eventually 

 unite. Bifurcation was observed in other beds and in some cases 

 one or more subdivisions thin out to disappearance. The Cre- 

 taceous coals of the Rocky Alountain region show the same feature. 

 Some of the features so marked in coal beds are equally char- 

 acteristic of peat accumulations. The description by Morton^^ may 

 be cited as representative ; the area has only a few square miles but 

 the conditions are those observed on a grander scale in the great 

 marshes of Holland and Belgium. At one locality Morton saw 



Brown and gray estuarine silt 6 o 



Upper peat 3 6 



Gray estuarine silt lo o 



Lower peat, forest bed 2 o 



Boulder clay 2 o 



The peat and silt were deposited in depressions ; they thin out in ap- 

 proaching the ridges. Sometimes the peat beds unite as they rise 

 on the slopes and occasionally after uniting they become continuous 

 with a surface bed which has never been covered. The lower peat 

 shows many trees in situ. The peat about each tree is somewhat 

 higher than that in the intervening spaces. The lower silt contains 

 neither shells nor bones. The upper peat, i to lO feet thick and 

 at times divided by silt, contains no upright stems but there are 

 prostrate stems with twigs and leaves as in a forest. The upper silt 

 is sometimes 20 feet thick, but, there, the upper peat is absent and 

 the silts are continuous. On earlier pages many citations were 

 made, recording irregularities in peat deposits, such as variation in 

 thickness, division or bifurcation of beds, disappearance of " splits" 

 by thinning out, even the phenomenon of the " Flying Reed." 



Relations of the Benches in Coal Beds. 



The total of coal in the separated splits may be greater or less 



than that in the undivided bed. The partings in the undivided bed 



*' G. H. Morton, " Further Notes on the Stanton, Ince and Frodsham 

 ]\Iarshes," Proc. Liver. Geol. Soc, Vol. VL, 1889, pp. 50-55- 



