106 Part I. Chapter I. 
were nearly completed, that is, toward the close of the Cretaceous period, 
the region was again uplifted, but unequally, so that at the same time its 
surface was warped. The streams had become sluggish, but the effect of the 
uplift was to stimulate them to renewed activity, so that they began cutting 
upon the last-formed peneplain, a process in which they are still engaged. 
The drainage streams of this region find their way either eastward to 
the Atlantic, southward directly to the Gulf, or to the Mississippi and thence 
to the Gulf. Those which drain westward into the Mississippi River leave the 
Blue Ridge with its gentle slopes and low gaps and flow northward in deepen- 
ing channels directly toward the higher and more rugged Unakas, which they 
cut through in narrow gorges. Emerging upon the Appalachian valley, those 
south of New River are intercepted by trunk streams, and led off toward the 
southwest. From New River to Georgia, the trunk stream is the Tennessee, 
which leaves its southeastward course and at the same time the broad Appa- 
lachian Valley by an abrupt bend at Chattanooga traversing the Cumberland 
Plateau in a narrow gorge much younger than other portion of its valley. 
Southward from the Georgia line, the trunk stream is the Coosa, which flows 
directly to the Gulf, and there is evidence, that the divide separating the 
Tennessee from the Coosa is extremely young and that until comparatively 
recent times all the waters flowing west from the Blue Ridge found their way 
directly to the Gulf across the present Tennessee-Coosa divide. 
b. Western Section; Rocky Mountains. 
The Cordilleran System comprises the following six regions beginning 
in the east: ı. the Rocky mountains; 2. the Great ranges; 3. the Northern or 
Columbian plateau; 4. the Southern or Colorado plateau; 5. the Sierra Nevada 
and Cascade range; 6. the Pacific Coast range'). 
The southern or north and south trending division of the Rocky Mountains 
is extremely well marked in its eastern edge, the ranges rising abruptly from 
a very gently sloping plateau. Here is a double range of Mountains quite 
distinctly marked in Colorado which enclose a system of high plateau-like 
valleys, known as the North, Middle, South and San Luis parks, ele- 
vated from 6000 to 10,000 feet. These parks are at the headwaters of the 
Platte, Colorado, Arkansas and Rio Grande rivers., Long’s Peak 14,271 feet 
(4350 m) and Pike’s Peak 14,147 feet (4312 m) are in the Colorado Range 
proper and are visible from the plains as conspicuous landmarks. 
The Sawatch range lies west of the head of the Arkansas River and its 
dominating peaks exceed 14,000 feet. Mount Harvard 14,375 feet (4380 m) 
is the highest peak, while the most noted summit to travellers, is the mountain 
of the Holy Cross 14,176 feet (4320 m) in altitude. The Elk Mountains 
next succeed on the west of the Sawatch range to be followed by the plateau 
region, which is characterized by the parks. Directly west of North Park is 
ı) Encyclopedia Britannica, ninth edition, Article United States XXIII: 796. 1888. 
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