Featherstonhaugh's Geological Report. 49 



which detached masses and layers of flint are found lying in 

 the chalk formation. The beds of the Cumberland river, two 

 or three miles above Nashville, and those near Herculaneum, 

 on the Mississippi, furnish striking instances, especially at this 

 last-named place, of the parallel disposition of the cherty layers. 

 The next formation in the series is the millstone grit and 

 shale, the inferior part of which, when well denned, consists 

 of shales, with occasional beds of limestone and coal. The 

 upper part is made up of coarse sandstones or grit, with pebbles 

 of quartz. This is an extensive formation in England, occu- 

 pying a considerable area in the central parts of that country, 

 between the 53d and 54th parallels of latitude, where it 

 divides the great coal field of the large manufacturing towns, 

 and runs up alongside of the carboniferous limestone to the 

 coal measures of the northern counties. As it proceeds to the 

 north, its character is less defined, and the formations between 

 which it lies run more immediately into each other, presenting 

 regular strata of limestone, with numerous subordinate beds of 

 coal. In the United States the millstone grit and shale is cut 

 through by the Cumberland river, in Whitely county, Ken- 

 tucky, to a depth of 700 feet ; the conglomerate part being about 

 500 feet thick, and the shale, with three horizontal good veins 

 of bituminous coal, each from three and a half to four and a 

 half feet thick, being about 200 feet. At the gap of Wills's 

 mountain, in the vicinity of Cumberland, there is a fine ex- 

 hibition of this formation, in an escarpment between 800 and 

 900 feet. The inferior is a reddish chocolate-colored shale, of 

 which the superior and greater portion is a gray quartzose 

 sandstone. On rising the Alleghany mountain* from Shell- 

 burgh, in Pennsylvania, the quartzose conglomerate incumbent 

 on the shale is found near the summit. Mr. R. C. Taylor, in 

 his instructive paper accompanying " a section of the Alle- 



* This is the general name given to that lofty ridge which separates the bitu- 

 minous coal measures from all the other Alleghany ridges, 



4 



