ature, they
often present an imposing magnitude. These greater elevations are
mountains; and we find them sometimes united in chains, sometimes
isolated, and at other times uniting to form elevated plains or table
lands. These table lands sometimes slope outwards, at others they are
surrounded by eminences that prevent the efflux of the waters, or only
admit them to pass through apertures made by their own action. Upon our
continent, table lands of the latter description are to be found of
great magnitude, entering as parts of the great system of the
Cordilleras or Andes; in Europe they are rare, but in Tartary, Persia,
and in central Africa, they occur, forming regions of great extent. In
general, the greater part of the mountains of a continent appear to have
a connexion more or less obvious; it has even been conceived that they
form the skeleton upon which the rest of the land has been deposited,
and which has determined the form of the continent. Thus we speak
habitually of chains of mountains. Mountains, however, do not always
present a continuous ridge, from which the peaks or more elevated
summits rise, but occasionally, the groups we call chains, are composed
of separate mountains divided by valleys; such are the mountains of
Scotland, of Sweden, and Norway; and such is the general structure of
the chain of mountains called in the state of New-York the Highlands, of
whose connexion and grouping we shall hereafter speak.

This being understood, namely, that by a chain or ridge of mountains we
do not necessarily intend a continuous elevation, the term may be
conveniently used in order to express the configuration of mountains.
These chains surround or border upon greater or less basins, which are
each distinguished by the name of the principal stream that conveys its
surface waters to the ocean, or they may, as has been stated, envelop a
table land, whence there is no issue for the waters, or no more than a
mere passage sufficient to afford them an outlet. Even if a map contain
no expression of the position of mountains, we can, by mere inspection
of the courses of rivers, determine the lines in which the chains are
directed, and, from the size of the rivers, judge in some measure of the
elevation of the district. Thus, on inspection of the map of Europe, we
find four of its greatest rivers rising at no great distance from each
other, the Rhine, the Rhone, the Danube, and the Po; here, then, we
might infer a great