In [Fig. 65] (entrance to Mammoth Cave, Kentucky) the stratification of the rocks is seen back of the entrance, within it, and at the right in the rocks of the foreground. (It is estimated that 12,000,000 cubic yards of limestone have been worn away or displaced in the excavation of the interior of this celebrated cave.)
[Fig. 66] (Natural Bridge, Virginia) also plainly shows the stratification of rock. What is the character of the rock? What was the agency employed in the sculpturing of both of these natural wonders?
In [Fig. 67] (Niagara Falls) the general direction of the mass is oblique. Notice how the water breaks as it falls, owing to the resistance of the atmosphere. In the “Palisades on the Hudson” ([Fig. 68]) notice the debris at the foot of the vertical wall of stone, forming what is called the talus slope. This is mostly overgrown with vegetation. In [Fig. 69] (a gorge in the cañon of the Colorado) the stratification of rock and the almost vertical cliffs are the principal features illustrated. [Fig. 70] represents a lofty peak in one of the cañons along the line of the Colorado. [Fig. 71] (Devil’s Slide, Weber Cañon, Utah) shows the mountain side as worn back leaving the trap rock projecting. (How came the harder rock there in this peculiar shape?) [Figs. 72 and 73] are geysers in Yellowstone Park—“Old Faithful” and “the Sponge.” In the latter, notice the corrugated formation, and the little stream that flows from its base.
MAP OF MEXICO WITH SUGGESTIONS FOR FIFTH AND SIXTH GRADE TEACHERS.
In the study of political divisions, details of structure, climate, etc., that were not brought out in the work on the continent as a whole, should precede the historical study.
Again let it be stated, that the method and questions here given are not to be followed literally; they are merely presented as suggestive hints to teachers, who should frame their own questions so as to best lead the pupil in his study to a realization of what the country is in itself, and how geographical conditions affect the history and civilization of a people.