GEOLOGY. 173 



County, North Carolina. He finds that the gneisses of Roan 

 Mountain, and the similar rocks at its western base, which 

 include considerable masses of very pure magnetic iron ores, 

 are Laurentian, but that there are indications of a belt of 

 Huronian schists along the western border. These Lauren- 

 tian gneisses to the eastward are succeeded by a great breadth 

 of thin -bedded gneisses, with highly micaceous and horn- 

 blendic schists, which he refers to the Montalban series, to 

 which belongs the narrow belt of dunite or olivine rock found 

 on the line of section near Bakersville. These Montalban 

 strata are intersected by numerous endogenous granitic 

 veins, which are extensively worked for mica, and yield, 

 moreover, finely cleavable orthoclase and albite, together 

 with beryl, apatite, and the rarer minerals autunite and 

 sarmarskite. The rocks of this series, often decomposed to 

 considerable depths, were found to occupy the greater part 

 of the country as far east as Salisbury, interrupted near 

 Statesville, however, by granitoid gneisses of Laurentian as- 

 pect. The belt of granular quartzite associated with lime- 

 stone, which is met with at the eastern base of the Blue 

 Ridge on the Catawba River, near Marion, is referred to the 

 Lower Taconic, of which it has the characters. Portions of 

 this quartzite are granular and flexible, and constitute the 

 rock known as flexible sandstone, or itacolumite. This gran- 

 ular quartzite is regarded by Hunt as identical with the 

 Primal w T hite sandstone of Pennsylvania. The gneisses of 

 Bellisle, near Richmond, Virginia, are, according to this ob- 

 server, to be referred to the Laurentian period. 



GEOLOGY OF THE CINCINNATI ANTICLINAL. 



Saflbrd has pointed out the evidences that this anticlinal, 

 which in Kentucky and Tennessee brings up between the 

 Appalachian and Illinois coal-basins the limestones of the 

 Trenton, was represented by an island during the Silurian 

 ao-e. There were two marked elevations alono; the line of 

 this axis, of one of which Cincinnati is near the centre, while 

 another is near Murfreesborough, Tennessee ; a depression in 

 Southern Kentucky separating the two. 



The summit of the Cambro-Silurian series, represented by 

 the Cincinnati shales, the equivalent of the Utica and Loraine 

 of New York, is in the southern area directly overlaid by the 



