100 Prof. C. H. Hitchcock.— The Coal Area of the U. States. 



In Pennsylvania the area amounts to 12,222 square miles, with an 

 average thickness of 40 feet of coal. The aggregate thickness of 

 the Measures varies from 825 to 2,535 feet.^ 



In Maryland the area is 550 square miles, in three separate basins. 

 The strata are 1,500 feet thick. There are thirty-two beds of coal, 

 one of fourteen feet, three of six feet each, and the others from one 

 to five feet.^ 



In West Virginia (with a little in Virginia) the coal area occupies 

 16,000 square miles. On the Kanawha River the strata are 1,250 

 feet thick, with twenty-four beds of coal, of which eleven have an 

 aggregate thickness of 51 feet. The coals are best developed along 

 this river.^ 



In Ohio Dr. J. S. Newberry mentions that the area is greater than 

 10,000 square miles, with a thickness of 1,500 feet of sediment, and 

 ten workable beds of coal. 



In Eastern Kentucky the area is stated to be 10,000 square 

 miles.^ 



In Tennessee the area of the Measures is 5,100 square miles. A 

 characteristic section gives a thickness of 578 feet. There are seven 

 beds of coal, with a total thickness of 14 feet. The beds vary 

 locally in their dimensions, more than has been reported elsewhere ; 

 perhaps because more carefully explored.'* The conviction is in- 

 creasing among American geologists that coal beds are not evenly 

 persistent on large areas, and constantly vary in thickness. 



In Georgia the area cannot be more than 170 square miles. 



In Alabama, a hasty measurement of a map furnished in manu- 

 script by Professor Safford indicates an area of 9,000 square miles. 

 The general character of the Measures must be like those of Ten- 

 nessee. 



4. The Michigan Basin. — The area is about 6,700 square miles, 

 with 123 feet thickness of Measures, and eleven feet (maximum) of 

 coal. In the centre the coal is thickest, thinning out to a mere line 

 around the edges.^ 



5. The Illinois Basin. — This occupies an area of 51,700 square 

 miles, including Illinois, Indiana, and Western Kentucky. 



In Illinois the Measures occupy an area of 41,500 square miles, 

 are from 600 to 2,500 feet thick, and contain ten beds of coal, with 

 an aggregate thickness of 35 feet.^ 



In Indiana the Measures occupy an area of 6,500 square miles, are 

 650 feet thick, and contain thirteen beds of coal, with an aggregate 

 thickness of 31 feet.'' 



In Western Kentucky' the Measures are 612 feet thick, including 

 the Millstone-grit. They contain eleven beds of coal. 



6. The Missouri Basin. — This is the largest of all the areas, com- 



1 Geology of Pennsylvania, by H. P. Rogers. 



^ First Keport upon the Geology of Maryland, by P. T. Tyson. 



^ Eeport to Chesapeake and Ohio R.R., by T. S. Ridgway. 



* Geology of Tennessee, by James M. Safford. 



* Geology of Michigan, 1861, by A. Winchell. 



« Final Report on the Geology of Illinois, by A. H. "Worthen. 

 ' Second Report on the Geology of Indiana, by E. T. Cox. 



