44 PHYSICAL GEOGRAPHY 



The Frostburg coal field, lying between Dan and Savage 

 mountains, covers an area of about two hundred square miles, 

 and its depth is computed to be at least fifteen hundred feet. 

 It rests unconformably upon a red sandstone containing Pro- 

 ducii, its bottom rising to the north-east and laterally towards 

 the Savage mountain to the north-west and Dan's mountain 

 to tlie south-east ; so that its strata dij) transversely west from 

 the latter chain and east from the former. This dip is irregu- 

 lar, the strata being in the south-east portion of the field more 

 curved towards Dan, and rising gently on the side of Savage, 

 whilst in its north-west division, the strata run up more rapidly 

 towards the latter than the former mountain. The inferior 

 strata that are continuous most probably crop out towards 

 both extremities at a considerable elevation in the mountain 

 forming the lateral limits of the basin, where they are covered 

 unconformably by strata of mill-stone grit. There are four 

 principal beds of coal embraced within this important deposite, 

 of which the main one is fourteen feet thick, being composed 

 of an alternation in unequal proportions of two distinct varie- 

 ties of the combustible, the predominant variety possesses con- 

 siderable lustre, the other is dull, hard, and somewhat resem- 

 bling Cannal coal. The elevation of this bed above tide is 

 nearly seventeen hundred feet and one thousand and fifty 

 feet above Cumberland. The next important bed is called the 

 eight feet bed, at an elevation of eight hundred and ninety- 

 eight feet above Cumberland ; it yields a solid coal with a 

 cubic fracture, containing SO per cent, of carbon, l^he deposites 

 of iron-ore, associated with the coal are found principally below 

 this bed; they are mostly argillaceous carbonates of iron, their 

 specific gravity varying from 3.2 to 3.5, and contain from 30 to 

 40 per cent, of metal. In the upper portions of the coal-field 

 red and brown ha3matites occur, but not in continuous depo- 

 sites. 



It is worthy of remark that in the whole of this coal forma- 

 tion, equal in extent to that which has been styled, 'the great 

 coal field of Northumberland and Durham,' in England, there 

 is no reason to suspect the occurrence of a single /«z//^, or dis- 

 location of the strata. Its surface is irregular, the ravines of 

 the water courses having penetrated into it to great depths, but 

 the irregularities are solely due to powerful excavating causes 



