State the process by which mountains are formed.
By what law does the elevating force accumulate?
Why, then, is the process of elevation spasmodic, and not constant?
How is the inclined position of strata produced?
How are strata brought into a vertical position over large areas?
Why do subsidences occasionally follow these movements of elevation? Mention instances.
Fig. 82.
What explanation is suggested of deep and extensive chasms?