1913.] STEVENSON— FORMATION OF COAL BEDS. 83 



remarked in the discussion that such fragments occur frequently in 

 Lancashire and that all are of quartzite; Bonney made the broader 

 statement that they are of common occurrence in coal. In the same 

 volume, J. Spencer referred to a granite fragment, weighing 6 

 pounds, which had been found in the Canister coal bed and he adds 

 that the surrounding coal was undisturbed. He remarked that 

 bowlders had been found at many localities, that they were always 

 isolated and that they had come from a distance. Gresley in 1890 

 reported that a well-rounded quartztite bowlder, 11 by 8 inches, had 

 been taken from underclay at i foot below the Mammoth coal bed 

 near Mr. Carmel, Pennsylvania. 



Orton^" says that prior to 1892 the Ohio bowlders had come from 

 the Middle Kittanning coal bed at Zaleski. The first was dis- 

 covered by Andrews in 1870, but many were discovered afterwards, 

 there being at times scores in a single room. The largest weighs 

 400 pounds and is in the State museum at Columbus. A new hori- 

 zon was made by finding a quartz bowlder, weighing 10 pounds and 

 10 ounces, at Mineral Ridge. It was in undisturbed coal at 2 feet 

 below the roof and it was covered with a closely adhering, slicken- 

 sided crust of coal. Stainier®^ gathered observations made by him- 

 self and others in the Belgian fields. Some of the fragments are 

 rounded and smooth, evidently rolled pebbles, while others are 

 irregular in form like concretions, but composed of sedimentary 

 material and so are to be regarded as foreign bodies. Pebbles of the 

 former type were obtained at 8 localities. They are not rare in 

 La Rochelle colliery of Charleroi at the 500-meter level but they are 

 wanting at the 250-meter level. The bed yields an impure coal and 

 earthy partings are numerous where the pebbles occur. The largest 

 is oval, 14 by 8 by 8 centimeters. Schmitz obtained rounded frag- 

 ments from localities in the Charleroi and Centre basins, and Lohest 

 found them in the Liege basin. The largest specimens weigh 20 and 

 25 kilogrammes. It is noteworthy that the Belgian fragments are 



" E. Orton, " On the Occurrence of a Quartz Bowlder in the Sharon Coal 

 of Northeastern Ohio," Amer. Joiirn. Sci., III., Vol. XLIV., 1892, p. 62. 



^ X. Stainier, " On the Pebbles Found in Belgian Coal Seams," Trans. 

 Manchester Geol. Soc, Vol. XXIV., i8g6, pp. 1-19. 



