THE MOUNTAIN. 75 



mations, which preserve their nrineralogical and fossilifer- 

 ous identity over extensive geographic surfaces. 



They vary from a few feet to several thousand feet in thick- 

 ness, and generally show a uniformity of mineralogical elements 

 through their entire thickness.* Thus in one formation the 

 silicious element predominates, presenting a series of hard 

 indestructible quartzose strata ; whilst, in another, the softer 

 aluminous element forms a series of shaly, slaty, or argilla- 

 ceous layers. 



Sometimes the calcareous or lime material alone predomi- 

 nates, and is found in ponderously stratified masses. 



The coals, or fossil carbon formations, make (see vertical sec- 

 tion) the upper portion of this series, and are mingled with all 

 the other elements in a stratified group of rocks. The mode 

 and style of distribution of this pile of rocks, (forming the sur- 

 face of the geological tally-board of the ages,) where it extends 

 over the different States, is a chapter of beauty and wonder. 

 Being all of them mechanical sedimentary rocks, and depo- 

 sited originally, with exception of the local undulatory and 

 oblique lines of original deposit, in a horizontal position, 

 constituting vast geological scales or Iamina3 on the surface 

 of the globe, they are now found folded and wrinkled, the 

 strata reposing at every angle of inclination, and presenting 

 a system of gigantic waves or lines of elevation, running 

 parallel and with great regularity for hundreds of miles. 



They present a topography of the most curious and inte- 

 resting character in the middle and eastern portions of the 

 range, forming long, narrow, keel-boat shaped valleys, with 

 abrupt cul-de-sac terminations, surrounded by high, sharp 

 mountains running like immense levees around them, and 

 which are only broken by the gorges of the streams which 

 flow through this region. 



This is the wild and picturesque scenery of the Appalachian 

 mountains and valleys, the gaps of whose beautiful rivers are 

 so celebrated by the Traveler, Artist, and Poet. 



* See vertical section and description of separate formations. 



