INTRODUCTION. 



is made up of coal measures, overlaid in its upper part by the confused ) 

 nowhere fertile, drift heaps of the great ice-sheet ; in the lower by the 

 soil of a river-plain. Its mountain barriers are composed largely of 

 bold outwardly facing parapets or ridges of Pocono sandstone the 

 mountain- maker of the region separated from the coal measures by 

 narrow bands of Mauch Chunk red shales and Pottsville conglomerates ; 

 eastward, however, the Pocono sandstone of Moosic mountain extends 

 from 12 to 20 miles, forming a broad, elevated tract, known as the Po- 

 cono Mountain Plateau, although here and there on its borders streams 

 cut down through it to the Catskill Sandstone beneath. In general it 

 is a wilderness of cool, tangled swamps, ponds, thickets, woods, of dry 

 barrens and rocks, rough in the extreme, with an elevation of from 1500 

 to 2000 or 2100 feet, and terminating eastwardly in an irregular escarp- 

 ment of high cliffs, such as are seen near Pocono Knob, in Monroe Co., 

 or the lower parapets which trace its northward trend. The glacial ice- 

 sheet was spread over this plateau, no doubt, although the great terminal 

 moraine of the continent passes across its lower portion. Erosion has 

 left several curious outlying peaks, capped with the hard Pocono sand- 

 stone, and standing as islands, surrounded by a sea of underlying Cats- 

 kill, worn down to a much lower level, such as Pocono Knob, in 

 Monroe Co., the high knobs (north and south) in Pike Co., the four 

 knobs of the Moosic mountain extension, including Ararat Peak and 

 Sugarloaf, in Wayne Co., and the still more distant and elevated double 

 peak of Elk mountain, in Susquehanna Co., the latter the highest moun- 

 tain in Pennsylvania beyond the extreme southwestern section of the 

 State. This Anthracite Valley lies wholly within two counties, Lacka- 

 wanna and Luzerne ; the Pocono plateau occupies a limited portion of 

 five, viz : Lackawanna, Monroe, Carbon, Luzerne and Pike counties, 

 named in order of the largest sandstone area- 

 It is the Flora of this crescent-shaped coal-valley, its mountain bar- 

 riers, the broad, rough plateau into which the eastern barrier blends, and 

 the isolated peaks belonging to this geological formation, which we have 

 denominated the Lackawanna and Wyoming Flora. 



While we believe it will be of value as a local catalogue, there was 

 an ulterior object in the study, which can only be completely attained 

 with the exhaustive examination of the region. Recalling the facts pre- 

 viously stated, it will be seen that this area has a singularly distinct 

 character of its own, geologically. It lies in the heart of the northern 

 Alleghcnies. It has a great variety of soil. It has considerable variety 

 of elevation ; the effect of a much greater elevation being brought about 



