14 Expedition to the 



tion limestone, are found peculiarly fertile and valuable, 

 having usually a favorable disposition of surface for agricul- 

 tural purposes, and abounding with excellent water. 



The transition limestone is not, however, of frequent oc- 

 currence westward of the Alleghany ridge. It appears on- 

 ly in the vallies, and is succeeded by clay-slate and the old 

 sandstone lying almost horizontally. The coal, with the ac- 

 companying strata of argillaceous sandstone and shale, are, as 

 far as we have seen, entirely horizontal. 



The country westward from the base of the Chesnut- 

 ridge, has an undulating surface. The hills are broad and 

 terminated by a rounded out-line, and the landscape present- 

 ing a grateful variety of fields and forests is often beautiful, 

 particularly when, from some elevation, the view overlooks 

 a great extent of country, and the blue summits of the dis- 

 tant mountains, are added to the perspective. 



Pittsburgh has been so often described, the advantages, 

 and disadvantages of its situation, and the gloomy repulsive- 

 ness of its appearance, have been so often and so justly por- 

 trayed, that we should not think ourselves well employed in 

 recounting our own observations. The Alleghany and the 

 Monongahela at Pittsburgh, where they unite to form the 

 Ohio, are nearly equal in magnitude ; the former, however, 

 on account of the rapidity of its current, and the transparen- 

 cy of its waters, is a far more beautiful river than the latter. 

 Its sources are distributed along the margin of Lake Erie, 

 and a portage, of only fifteen miles, connects its navigation 

 with that of the St. Lawrence. 



About the sources of the Alleghany are extensive forests 

 of pine, whence are drawn great supplies of lumber, for the 

 country below as far as New Orleans. On French Creek 

 and other tributary streams, are large bodies of low and ra- 

 ther fertile lands, closely covered with forests, where the 

 great Weymouth pine, and the hemlock spruce are intermix- 

 ed with beech, birch, and the sugar maple. The great white 



