Valley of the Lackawanna and of Wyoming. 309 



Valley of Wyoming and of the Lackawanna. 



The double barrier of nearly parallel mountains, through whose 

 included valley, flow the Susquehanna and its tributary the Lack- 

 awanna, is a perfectly well defined coal formation, and its geolog- 

 ical structure is equally intelligible and interesting. Coal is often 

 situated in basins ; this region is, however, not a basin, but rather a 

 trough ; and its strata, seen in a transverse section, would present a 

 series of elliptical curves. Leaving out of view its irregularities, this 

 valley may be regarded, as the lower half of a vast flattened tube, ly- 

 ing horizontally, within which are laid a series of sections of smaller 

 tubes, whose sides continually diminish, in height, and end with the 

 omission of those towards the centre ; the bottom of these sections 

 represents the strata in the lower parts of the valley, and the sides, 

 those of the slopes of the hills and mountains. The Lackawanna 

 creek and Susquehanna river flow through a natural canal, scooped 

 out longitudinally, in the lower part of the upper strata ; winding, ir- 

 regularly, in a line, nearly, but not exactly central, and tending most 

 towards the side which represents the western barrier of mountains. 



The annexed wood cut is intended to give an ideal section of the 

 strata as regards their position and arrangement, without any preten- 

 sion to accuracy in the proportions or number of strata; and the occa- 

 sional irregularities, as well as the steep ascent up the mountains, to 

 the extreme right and left, are intentionally omitted. 



Ideal Section, at Wilkesbarre. 



The strata or natural beds included in this great valley are those 

 of the Anthracite coal formation. The particular strata that require 

 to be noticed are only three. Supposing them all present at any 

 particular place, they are arranged as follows, — beginning at the top ; 



