The ever repeating fracture design of the earth’s crust is not restricted to the mountain masses which it has broken up, and the unity of which it has done so much to conceal. It extends far outside the margin of these masses, and is in fact common to whole continents and perhaps even to the planet as a whole. The part played by this design of fractures in the control of the sculpture of landscapes it would be hard to overestimate. Through its influence the striking features molded by one agent have been merged in the contrasted shapes developed by another. It is the great outline blender in the creation of nature’s masterpieces of form and color. Thus the lines of this mysterious fracture network, though stamped in indelible characters upon our landscapes, are generally lost in the ensemble effect and may long remain undiscovered. Like a moss-grown inscription upon a slab of marble, though veiled, it may yet be deciphered; and if the veil be withdrawn, the runic characters are disclosed, and one of nature’s laws lies open before us.
Reading References for Chapter XXXI
Mountain arcs or festoons:—
Ed. Suess. The Face of the Earth, vol. 2, 1906, pp. 201-207; vol. 4, 1909, pp. 498-542.
Block mountains:—
G. K. Gilbert. Surveys West of the 100th Meridian (Wheeler), vol. 3, Geology, Washington, 1875, Pt. 1, pp. 19 et seq., 48.
J. W. Powell. Report on the Geology of the Eastern Portion of the Uinta Mountains and a Region of Country Adjacent thereto, U. S. Geol. and Geogr. Surv. Ter., II Div. Washington, 1876, pp. 218.
John W. Gregory. The Great Rift Valley. London, 1896, pp. 422.
Laccolites and bysmalites:—