254 



MILLSTONE GRIT. 



from clay slate by being an aggregate of mineral 

 particles, instead of being wholly made up of a sin- 

 gle mineral species. These two rocks alternate 

 with each other without any determinate order. 

 They sometimes lie below as well as above the coal 

 measures, as will appear by examining the sections 

 above given. This group is sometimes very rich 

 in metallic ores, such as lead, copper, mercury, 

 iron, zinc, and manganese, which occur in detach- 

 ed spots, in nodules or beds, but never in veins. 

 We also find in the grit phosphate of lime, fluor 

 spar, sulphate of baryta, &c. 



In Whitely county, Kentucky, the millstone grit 

 is cut through by the Cumberland River to the 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 300 

 feet. Near Cumberland there is a fine exhibition 

 of this rock, in an escarpment between 800 and 900 

 feet high. The millstone grit also abounds in the 

 State of New- York, and we find it throughout Her- 

 kimer and Oneida counties, with a thicKness of 30 

 or more feet. It seems to be composed of rolled 

 stones or pebbles, and the brine-springs lie above it. 



It may be stated, then, as a general fact, that the 

 Blue Ridge System contains no coal ; the Appalach- 

 ian System contains the anthracite ; and the Alle- 

 ghany the bituminous coal measures, which also 

 spread to the west over an immense area, and are 

 traceable, as a single geological formation, far be- 

 yond the Mississippi. 



Mr. R. C. Taylor, a practical engineer and geolo- 

 gist, has offered some considerations to show that 

 it is very improbable, as Mr. Featherstonhaugh and 

 others expect, that coal will be found in any quan- 

 tity in the State of New- York ; and Mr. Hildreth 

 remarks that, with the exception of the Susque- 

 hanna and its tributaries, and Will's Creek, emp* 



