GENERAL MEETING. 23 
related to the features controlling other classifications that a large 
share of the boundaries coincide with lines previously drawn and 
the selection of appropriate designations is little more than a choice 
between names previously given. 
There are some parts of the United States where the drainage 
basin affords the best unit for the purposes of the physical geo- 
grapher. This holds for the basin of the Laurentian lakes, the basin 
of the Red River of the North, and the great Interior basin. But in 
the Appalachian region the drainage cannot be used. There is how- 
ever in this region a remarkable line of demarcation, known as the 
fall line, which finds its manifestation in connection with the drain- 
age, and is the natural boundary of an important division. If we 
follow the course of any river in the eastern part of the United 
States, south of New England, from its source to the sea, we discover 
that at a certain point it ceases to be rapid and turbulent, and 
becomes broad and slow-moving, and in many cases an estuary of 
the sea. At the point where this change occurs there is usually 
a fall or rapid. The familiar local example is the Potomac at 
Little Falls. I have traced this fall line from near Troy, N. Y., 
southward by the interior cities of Washington, Richmond, Colum- 
bia, and Montgomery, and thence to the Muscle Shoals of the 
Tennessee river. It is always the lower limit of water power 
and often the upper limit of navigation, and is therefore marked, 
and destined to be marked, by cities and towns of importance. In 
its northern portion it is at the head of tide, and nowhere does it 
exceed an altitude of 200 feet. It may yet be determined that it 
crosses the Saint Lawrence at the Lachine rapids and the Missis- 
sippi above Cairo, although no rapid exists at that point. Whether 
it may be traced farther and into Mexico remains to be determined. 
From the fall line to the shore of the sea there is a region having 
a gentle slope, traversed by slow-moving rivers, and fringed at al- 
most a dead level by deltas, swamps and everglades. This I have 
entitled the coastal plains, including as subdivisions the Atlantic 
plains and the Gulf plains. 
The area bounded by the fall line and by the Mississippi and 
Ohio rivers and a part of the drainage divide of the Laurentian 
lakes, might be taken as a whole as the Appalachian region, but it 
includes three sections so distinct in topographic type as to warrant 
separate designations. 
From the Ohio river southeastward and from the Mississippi 
