Relief Forms subject to fixed Laws.—Every element of form which gives character and expression to a landscape is determined by fixed laws. It is true that the arrangement of hills and vales does not conform to any simple geometric pattern. The sculpturing forces are complex, and the net result of their interaction is necessarily also complex and promiscuous; still the action of each single force is regular, exact and unvarying, and the complex results are harmonious.
Predominance of Curves over Angles.—Most pleasing to the eye are those forms in a landscape which are bounded by curved lines and surfaces. Most striking, picturesque, rugged and impressive are those which are bounded by planes and angles. The former are far more common, and are produced by weathering and the washing of water. The latter depend upon the primitive structure of the rocks. Angular structural forms are the rough blocks . . .