284 GEOLOGICAL EXCURSION TO THE ROCKY MOUNTAINS. 



road ii thickens greatly, attaining 900fee1 in Randolph and Pocahon- 

 tas countiea, W . 7a., 1,100 feet in Greenbrier County, and on New 

 River, in Summers County, a deep boring, 12 miles above Hinton, 

 finds it 1,415 feel thick. 



The M'liirh Chunk tied Shale division of No. XI consists of bright 

 red shales, impure limestones, and massive, green sandstones, and fre- 

 quently contains iron ore near the top in irregular layers and nuggets. 



The thickness of this scries on the Haiti re & Ohio oear Piedmont is 



860 feet, but on Cheat river, near Rowlesburg, it is reduced to only half 

 that amount, or ill) feet, while westward from this latter locality the 

 Mauch Chunk continues to dwindle in thickness, being only 140 feet in 

 the oil borings at Mannington, and probably not more than half of ihis 

 at Bellaire on the Ohio river, while further northwest in Ohio it seems 

 to disappear completely. 



These beds are quite variable in thickness along the Appalachian 

 Mountain region, being 3,000 feet at Mauch Chunk. Pa., and about 

 2,500 in Greenbrier county, Wesl Virginia. Like all of the Paleozoic 

 deposits, they attain their maximum thickness to the east, and dimin- 

 ish rapidly westward. The flora of these beds seems to be more closely 

 related to that of the Catskill below than to that of the Coal Mcas 

 ures above. 



The PotUvUle Conglomerate, Millstone QHt, etc. (XJJ). 18 — -The basal 

 member of th< i Coal Measures, rests unconformably (not in dip but by 

 erosion) upon the underlying Lower Carboniferous beds, and consists 

 of white, hard, ami often conglomeritio sandstones, interstratilied with 

 dark shales which contain coal beds (New River series), thin and insig- 

 nificant along the Baltimore & Ohio Railroad and elsewhere to the 

 northeast, but thickening up to the southwest, and becoming the famous 

 coking and fuel coals of New River, West Virginia, and the Pocahontas 

 region of Virginia and West Virginia. 



The sandrocks of this series, being composed of nearly pure quartz 

 grains and therefore almost indestructible by atmospheric agencies, 

 have played a very important part in forming the wild scenery along 

 the Alleghanies; in fact, this series conspires with the Pocono beds 

 below to make the Alleghanies, the Pottsville beds topping out the 

 highest summits, like Eagle Pock near Deer Park, on the "backbone" 

 of the Allgehanies (.'J,. '>•"><> feet). The wild scenery where the Baltimore 

 and Ohio passes out of the Cheat liver canyon, west from Rowlesburg, 

 is made principally by these beds. Wherever these rocks come to the 

 surface, they form "rock cities." waterfalls, canyons, mountains, and a 

 rugged, picturesque country generally. The series varies greatly in 

 thickness, as will be seen by the following: 



