ABSTRACT
Many of the valleys on the surface of the earth are formed by the mechanical agency of water; for, on examining them we find that their direction does not correspond to the internal structure of the stone; that the strata and beds on opposite sides of the valleys are similar, but intersected. All valleys, however, are not formed in the same manner; for many and very extensive valleys are formed by mountain groups disposed in a circular form … others by the original inequalities of the crust of the earth; some by the unequal deposition of formations, and others by the widening of great rents.
