74 COAL MEASURES. 



CHAPTER XXXIII. 



COAL MEASURES. 



^ 157. The name " Coal Measures" originated among the miners of England 

 before Geology became a science. It is familiarly used in the earliest text-booka 

 on Geology, as a scientific term, which was understood without a definition. It is 

 applied to part of the Carboniferous System, and not to Cretaceous or Tertiary 

 Coal regions. The Coal Measures consist of beds of sandstone, shale, slate, lime- 

 stone, clay, and coal, which are variable in their geographical distribution. The 

 area covered in North America is estimated at about 210,000 square miles, nearly 

 all of which is included in five fields, four of which are in the United States and one 

 in Nova Scotia. Canada and British America are destitute of this important dep «t , 

 as well as many States in the Union, among which are Maine, New Hampshire, 

 Vermont, Connecticut, New York, New Jersey, Delaware, South Carolina, Florida, 

 Mississippi, Louisiana, Minnesota, and Wisconsin. 



§ 158. The Coal Measures of Novia Scotia rest upon Subcarboniferous rooks, 

 and are divided into the Millstone Grit, Middle Coal Formation, and Upper Coal 

 Formation. A section of the Millstone Grit is as follows: 1. Reddish shales and 

 red and gray sandstones, having a thickness of 2,082 feet, containing no ooal, and 

 poor in fossils, except a few drifted trunks of trees. 2. Sandstones, red shales, and 

 a few dark-colored shales, with nine small or rudimentary coal-beds, with a total 

 thickness of 3,240 feet. The underclays abound in Sigillaria, and some strata are 

 quite fossiliferous, containing plants, crustaceans, and fish. .'!. Red and gray sand- 

 stones, red and chocolate shales, arenaceous conglomerates, and thin beds of con- 

 cretionary limestones, having a thickness of 700 feet, making a total thickness of 

 6,000 feet. The Middle Coal Formation includes the productive coal-beds, and 

 contains no marine limestones or conglomerates. It consists of shales and sand- 

 stones, and has a thickness of 4,000 feet. The Upper Coal Formation consists of 

 shales, sandstones, conglomerates, limestone, and coal, and has a thickness of 3,000 

 feet. On Cape Breton, the last two divisions have a thickness of 10,000 feet, 

 making the maximum thickness of the Measures, 10,000 feet. From Nova Scotia 

 the Measures dip south-west, and reappear in the form of a subtriangular basin in 

 New Brunswick. The area in Nova Scotia and New Brunswick is 18,000 square 

 miles. The coal is all bituminous. There are 72 seams and numerous dark bands 

 containing more or less carbonaceous material. A coal-bed at Pictou is 37^ 

 feet thick, and another 22^ feet. A large part of the coal-basin is beneath the 

 waters of the Atlantic and the Gulf of St. Lawrence. 



§ 159. The first coal-field in the United States is the Appalachian, which extends 

 over important parts of Pennsylvania, Virginia, West Virginia, Maryland, Ohio, 

 Kentucky, Tennessee, and Alabama. Its length is 875 miles, and width from 30 

 to 200 miles. The anthracite region is in the north-eastern part of Pennsylvania, 

 and does not cover 500 square miles. The coal-beds form synclinals, auticlinals, 

 or stand highly tilted on their edges, but are never horizontal. All the other parts 

 of this great area, estimated at 60,000 square miles, produce only bituminous coal, 

 and the beds may be horizontal or possessed of a slight dip, to which all the strata 



