Notice of a Geological Model. 89 



sary, as they have been recently piibhshed, at considerable length, 

 in the form of reports to the proprietors of the soil.* What re- 

 mains to be added here, under this head, will occupy a brief space.f 



Ranging along the southern margin of this coal-field, appear 

 nine principal transverse sections, *' gaps" as they are locally term- 

 ed, which cut through Sharp mountain. Through these ravines, 

 many hundred feet in depth, the drainage of the coal area descends 

 southward ; and by the same avenues the highly inclined coal seams 

 are intersected. The height at which these coal seams can now 

 be reached within the gaps, without expensive tunnelling, varies 

 from eight hundred to eleven hundred feet above the level of the 

 sea ; and as the summit attains an elevation of sixteen hundred and 

 fifty feet, there are therefore from four hundred to eight hundred 

 and fifty feet, measuring perpendicularly, of coal, capable of being 

 worked, above those points of intersection. 



The number, thickness, compactness and density of these coal 

 seams increase as we pass eastward along the counties of Dauphin, 

 Lebanon and Schuylkill. At the same time, and in a correspon- 

 ding degree, or rather in a reverse ratio, the amount of bitumin- 

 ous and volatile matter, contained within the coal, diminishes ; 

 passing from a bituminous or semi-bituminous coal, which yields 

 a bright blazing fire, and at some points is convertible into coke 

 of good quality, to a compact anthracite, on the borders of Schuyl- 

 kill county. This fact is exemplified in the series of analyses 

 made on behalf of the proprietors and published in 1840, and sub- 

 sequently by another series, recently embodied in the state geo- 

 logical report.^ The prevailing breadth of this southern fork, 

 measuring from red shale to red shale, is about a mile ; except 

 towards the western termination, where it is only about one thou- 

 sand feet to one thousand and two hundred feet wide, for three 

 or four miles. In this range the lower conglomerate, interposed 

 in great thickness towards the eastern extremity of the Schuyl- 



* Vide report on the coal lands, mines, &c., of the Dauphin and Susquehanna 

 Coal Company, by Richard C. Taylor, president of the board of directors. Report 

 of the geological examinations, &c. of the Stony Creek Estate, in Dauphin and 

 Lebanon counties, by Richard C. Taylor. Philadelphia, 1840. 



t At the request of the author, we have, in printing the memoir, omitted many 

 details which were embodied in the original ; because without the assistance of 

 maps and diagrams, they could not be rendered sufficiently intelligible to the 

 reader. 



X See also a series of analyses of coals from this region, published in Vol. xL, 

 p. 373, of this Journal, by Mr. M. C. Lea. 



Vol. xLi, No. 1.— April-June, 184L 12 



