^^ rOec. 19, 1884. 



graphical map of the State from original surveys shall have been made, 

 the geology can tlien be outlined upon it, by using the information con- 

 tained on the?e maps, with very little additional work in the field." 



Division II, will contain the sheets of the Anthracite Survey. These 

 sheets will be grouped under the following heads : 



Mine sheets, scale 800 feet to one inch, 1 -9600th of nature. The area 

 covered by each sheet, inside of the borderlines, is 15.67 square miles. On 

 these sheets will be represented the plan of all the mines and the shape of 

 the floor of the most extensively developed coal bed (Mammoth bed prin- 

 cipally), where mined, and its most probable structure in undeveloped 

 areas, by contour curve lines fifty feet vertically apart ; also the surface 

 geological features. 



Topograplucal sheets, scale 1600 feet to one inch, l-19,200th of nature. 

 The area embraced within the border line of each sheet is 62. C8 square 

 miles. On these sheets will be represented the topography of the surface 

 by contour curve lines ten feet vertically apart. 



Cross section sheets, containing vertical cross sections, scale 400 feet to 

 one inch, 1 -4800th of nature, showing the shape of the coal beds, where 

 mined, and their most probable structure in undeveloped areas, accom- 

 panied by special maps and sections of the areas referred to, on various 

 scales. 



Columnar section sheets, containing perpendicular columnar sections, 

 showing the thickness and character of the coal measures, scale forty feet 

 to one inch, l-480th of nature ; and of the coal beds, scale ten feet to one 

 inch, l-120th of nature ; accompanied by special sections and diagrams on. 

 various scales. 



Miscellaneous sheets, containing special illustrations directly connected 

 with the history, mining and geology of the region. 



Division III, will contain the maps and sections relating to the petro- 

 leum and bituminous coal fields, published on various scales. 



Division IV will contain the topographical maps, from the surveys of 

 A. E. Lehman, of the South Mountain in Adams, Franklin and Cumber- 

 land counties, and the topographical maps of the Great Valley between 

 Easton and Reading, constructed from the surveys of Messrs. d'Invilliers, 

 Berlin and Clarke. These maps are published on a scale of 1600 feet to 

 one inch, 1-19, 200th of nature, and the topographical features are delineated 

 by contour curve lines, either ten or twenty feet vertically apart. 



Division V will contain the geological maps and sections relating prin- 

 cipally to the Silurian and Devonian formations in Central Pennsylvania, 

 and geological cross sections of the Philadelphia rocks in the south-eastern 

 portion of the State. 



