The valley of French Broad, including that of Nolachucky, occupies a triangle of 90 miles base, with 70 miles perpendicular ; traversed nearly cen trically by N. Lat. 36° and Long. W. from Wash ington City.
Tennessee proper, though a minor constituent even when compared with the French Broad, has by the course of original discovery given a generic name to the valley. The extreme source of Ten nessee is in Rabun county, Georgia. Issuing thence, from the northern spurs of Blue Ridge, by the name of Estato creek, it enters North Carolina be tween Haywood and Macon counties, and gradually winding from a northern to a northwestern course, receiving tributary creeks from both counties, but particularly the Tuckaseege from Haywood, tra verses the gap between the Unika and Iron moun tains, enters Tennessee, and, separating Monroe from Blount, falls into Holston opposite the south ern part of Roane county. The entire comparative length of Tennessee is about 85 miles ; of which 5 are in Georgia, and 40 in each of the other two states.
Hiwassee is the lowest stream deserving the name of a river which enters Tennessee from the left. This confluent has its extreme sources in Rabun county, Georgia, but yet small creeks, they enter Macon county of North Carolina, where they unite, and assuming a course of northwest by west, traverse the Unika or Iron mountain, enter Ten nessee, and separating the Arnoi district of the Cherokee territory from M'Minn county, falls into the main volume of Tennessee river, about 50 miles comparative course below Kingston.
The distinctive name of Tennessee is applied to the volume below the junction of Holston and French Broad. Already a large stream, it is, how ever, greatly augmented at Kingston by the influx of the Clinch. The general course of Clinch is maintained below Kingston, and continuing south westward, by comparative courses, 160 miles, re ceiving the Hiwassce from the left and the Se quatchee from the right, Tennessee abruptly turns to northwest by west, and piercing Cumberland mountain, merges into its lower valley, after a com parative course, following either the Clinch or Hol ston, of 350, or by the French Broad, SOO miles.
Including all the minor valleys, Upper Tennessee drains an elongated ellipse of 350 miles larger axis, and with a shorter axis of 120 miles. The larger axis extends in a direction a little E. of N. from the great bend at the passage through Cumberland mountain to the sources of Holston; and the shorter axis stretching from the sources of French Broad in the Blue Ridge to those of the extreme north western branches of Powell's river in Cumberland mountain. The area of the whole elliptical valley is about 24,000 square miles.
It would be very satisfactory to have been able to give the relative height of the extremes of this in teresting physical section, but this result can be only stated by approximation. Without estimating the mountain ridges, the mean arable surface of Tazewell county of Virginia, has been estimated at 1200 feet ; we may therefore assume at least 1500 feet as the relative elevation of the fountains of Tennessee. The surface of the water passing through Cumberland mountain is at the utmost not more than 750 feet elevated above the Gulf of Mexico ; hut with that allowance, Upper Tennessee valley will have, on a plain of 350 miles, 750 feet fall, or something above two feet per mile. The real descent is probably rather greater than shown by this estimate.
Descending from the extreme fountains in Vir ginia, the valley widens as the mountains recede from each other, and again contract as the same chains again reapproach gradually towards each other at the northwestern angle of Georgia, and the northeastern of Alabama. At the latter point below the influx of Sequatchec, well known under the name of Nickajack, all the large confluents have united, and the Blue Ridge and Cumberland moun tains have inclined to within less than forty miles of each other. Below Nickajack, in a distance of 60 miles, the valley becomes more and more con fined in width, and without receiving a single creek of twenty miles course, the large volume pours down its mountain channel, the two chains still ap proaching each other until their actual contact forces the stream through a gorge of Cumberland.