FIVE TYPES OF EARTH-SURFACE IN THE UNITED STATES. 



307 



of every part of the United States, and of Canada, east of the Mississippi River, I was sur- 

 prised at the beauty of the whole representation now for the first time made to the eye. 

 The correlation of parts was very fine, in a geological sense. The plateau of the coal, 

 commencing in Alabama and cut off square by the Hudson, contrasted strongly with the 

 essentially unbroken run of the Quebec Group and Laurcntian System, from Georgia to 

 the extreme east end of Canada ; while the open valley of the Lower Silurians, every- 

 where keeping the two systems apart, was most remarkable. The sweep of the Lower 

 Devonian and Upper Silurian escarpments around the end of the Catskill, with their 

 long straight lines through IS'ew York and their curve through Western Canada, was 

 likewise beautiful. But the charm of the map lay in its unmistakable utterances respect- 

 ing different topographical types of earth-surface or strongly contrasted systems of erosion, 

 lying in masses, side by side, or running for long distances in parallel belts. 



Thus, for instance, the eye takes in at a glance the whole Blue Ridge, Highland, and 

 Green Mountain belt, full of short sharp ridges, in parallel order, but in echelon arrange- 

 ment, with irregular summit lines, rising into knobs and peaks from 3000 to near 7000 

 feet above the sea. 



Behind it runs the belt of the Appalachians, composed of interminably long and narrow 

 barrow-mountains, with level summits, seldom 1000 feet in height, looped and gophered 

 in an intricate and artificial style, with lens-shaped coves in the northern part ; and on 

 the other hand, in the Southern States, terminating in pairs of perfectly straight ridges, 

 cut off short by faults. 



Behind these, again, lies the Great Cumberland-Allcghany-Catskill Plateau, with its 

 horizontal geology and its quaquaversal, arborescent drainage-system, boldly contrasting 

 with the Appalachian topography in front of it, and settling the questions of mode and 

 agency in favor of slow aerial denudation. 



Still further west, the low finger-shaped bounding ridges and central plains of the Blue 

 Grass country of Kentucky and Ohio shows another but allied type. 



And in the east, the wide belt of low sand-hills, southeast of the Blue Ridge, and the 

 immense cretaceous and tertiary flats of the tidewater country, crenulated with bays and 

 covered with dismal swamps, presents a fifth, differing from all the rest. 



This map is now in England. But before it left tins country, Mr. Bache obtained per- 

 mission to have it photographed in sections, in the office of the Coast Survey. And it is 

 one of these sections that I have redrawn on stone and offer as a first specimen of what 

 we have a right to expect when the United States, at peace once more among themselves, 

 and free from the curse of slavery, thank God, shall take up in earnest the work of study- 

 ing and expressing to the eye the character of the countries which they possess in com- 

 mon. During the Rebellion, however, these topographical section-maps were of a more 



